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20192373 | 3D modeling of the electron energy distribution function in negative hydrogen ion sources. | For optimization and accurate prediction of the amount of H-ion production in negative ion sources, analysis of electron energy distribution function (EEDF) is necessary. We are developing a numerical code which analyzes EEDF in the tandem-type arc-discharge source. It is a three-dimensional Monte Carlo simulation code with realistic geometry and magnetic configuration. Coulomb collision between electrons is treated with the "binary collision" model and collisions with hydrogen species are treated with the "null-collision" method. We applied this code to the analysis of the JAEA 10 A negative ion source. The numerical result shows that the obtained EEDF is in good agreement with experimental results. |
20192375 | Experimental study for 15-20 mA dc H- multicusp source. | Recently, a new H- source and test stand was developed at CIAE. The design of this new source is based on the experience on our previous 10-15 mA H(-) ion source and the source at TRIUMF. Major efforts include the study of the virtual filter magnetic field, confining magnetic field, filament shape and location, the vacuum improvement on the extracting area, the extraction optics, new control and interlock system of the power supplies. More than 15 mA of H-beam was obtained for 36 h with stability of +/-0.5%. The normalized emittance of 0.48pi mm mrad (4 rms normalized emittance) were measured with approximately 8 mA dc beam. Further experimental studies are proceeding in an effort to reach 20 mA with reasonable emittance at this moment. More study plans are conducted, e.g., building a longer source body and using cesium injection to get better emittance, which will be presented as a separate paper at this conference. |
20192376 | Simulation of cesium injection and distribution in rf-driven ion sources for negative hydrogen ion generation. | Cesium seeded sources for surface generated negative hydrogen ions are ponents of neutral beam injection systems in future large-scale fusion experiments such as ITER. Stability and delivered current density depend highly on the cesium conditions during plasma-on and plasma-off phases of the ion source. The Monte Carlo code CSFLOW3D was used to study the transport of neutral and ionic cesium in both phases. Homogeneous and intense flows were obtained from two cesium sources in the expansion region of the ion source and from a dispenser array, which is located 10 cm in front of the converter surface. |
20192377 | Plasma meniscus and extraction electrode studies of the ISIS H- ion source. | In order to reduce the emittance and increase the transported beam current from the ISIS Penning-type H(-) ion source, improvements to the extraction system are required. This ion source is currently missioned on the front end test stand at the Rutherford Appleton Laboratory, which demands higher extraction energies, higher beam currents, and smaller emittances. To facilitate this, the present geometry requires optimization. This paper details the experimental and simulation studies performed of the plasma meniscus and the possible electrode geometry modifications needed to extract the highest quality beam. |
20192378 | Commissioning of the new H- source for Linac4. | As part of the CERN plex upgrade, a new linear accelerator for H(-) (Linac4) will start its operation in 2014. The source for this linac will be a 2 MHz rf driven H(-) source which is a copy of the very successful source from DESY. In this paper the design and the first results of missioning are reported. missioning has progressed successfully, and no major obstacles have been identified which will prevent reaching the goal of 80 mA H(-) beam current, 45 keV beam energy, 0.4 ms pulse length, and 2 Hz repetition rate. The source is producing up until now a stable beam of 23 mA, 35 keV, and with a repetition rate of 0.83 Hz. |
20192379 | Spallation neutron source saddle antenna H- ion source project. | In this project we are developing an H(-) source which will synthesize the most important developments in the field of negative ion sources to provide high current, high brightness, good lifetime, high reliability, and high power efficiency. We describe two planned modifications to the present spallation neutron source external antenna source in order to increase the plasma density near the output aperture: (1) replacing the present 2 MHz plasma-forming solenoid antenna with a 13 MHz saddle-type antenna and (2) replacing the permanent multicusp magnetic system with a weaker electromagnet. |
20192380 | Emission characteristics of H- ion source with inverse gas magnetron geometry. | The work is dedicated to the experimental investigation of the intense volume-plasma H(-) ion source. Preliminary experimental researches of two parameters of the upgraded source--emission density of H(-) ions and gas flow--are represented below. In plasma volume of noncesium H(-) ion source, the conditions for obtaining of increased density of H(-) ions in the field of adjoining to the emission aperture were realized. The advancing of electrode system of the emission chamber of a source has allowed receiving the value of an emission density of H(-) ions equal to 600 mA/cm(2). |
20192381 | Electrode activation in cesium-free negative ion sources. | Features of emission electrode activation leading to enhancement of negative ion emission in cesium-free discharges are discussed. In some ion sources with cesium-free discharges, the emission of negative ions has been increased significantly by emission electrode activation using strong heating of the negative biased electrode by discharge plasma. A simple explanation of this enhancement is that it is due to an accumulation on the emission surface of the plasma electrode of impurities with low ionization potential that decreases in surface work function and increases the secondary emission of negative ions similar to "Cesiation." The negative biasing of emission surface is important for accumulation and trapping the impurities on the emission surface. To effectively control the activation process it is important to directly detect the evolution of the work function and the impurity concentration during electrode activation with enhancement of negative ion emission. |
20192382 | Emittance improvement efforts on the 15-20 mA dc H- multicusp source. | A 15 mA beam from the 15-20 mA dc H(-) multicusp source has been obtained at China Institute of Atomic Energy. In order to improve the emittance of extracted beam from this new multicusp source, some measures have been taken, i.e., increasing the length of the ion source body, improving the vacuum in the extraction area, injecting cesium vapor into the ion source, etc. The hardware, including the lengthened source body, the improved back cover and cesium heating system, and the extraction vacuum box, will be described. Initial results for these efforts aimed at emittance improvement will also be given in the paper. |
20192383 | Design of a versatile multiaperture negative ion source. | Negative ion sources are a ponent of the neutral beam injector to be installed in the International Thermonuclear Experimental Reactor. At present research and development activities address several important issues related to beam extraction, optics, and optimization. Together with the design of real size devices and the accumulation of atomic cross section databases, a relatively small negative ion source [130 mA of H(-) at 60 kV, named Negative Ion Optimization phase 1 (NIO1)] is under construction at Consorzio RFX to contribute to benchmark numerical simulation tools and to ponents, such as emittance scanners, beam dumps, and cesium ovens. NIO1 design, magnet configuration, and rf coupling simulations are described. |
20192384 | Cesium control and diagnostics in surface plasma negative ion sources. | For efficient and reliable negative ion generation it is very important to improve a cesium control and diagnostics. Laser beam attenuation and resonance fluorescence can be used for measurement of cesium distribution and cesium control. Resonant laser excitation and two-photon excitation can be used for improved cesium ionization and cesium trapping in the discharge chamber. Simple and inexpensive diode lasers can be used for cesium diagnostics and control. Cesium migration along the surface is an important mechanism of cesium escaping. It is important to develop a suppression of cesium migration and cesium accumulation on the extraction system. |
20192386 | Development of an H- ion source for Japan Proton Accelerator Research Complex upgrade. | A cesium (Cs) free H(-) ion source driven with a lanthanum hexaboride (LaB(6)) filament was adopted as an ion source for the first stage of the Japan Proton Accelerator Research Complex (J-PARC). At present, the maximum H(-) ion current produced by the ion source is 38 mA, using which J-PARC can produce a proton beam power of 0.6 MW by accelerating it with the 181 MeV linac and the 3 GeV rapid cycling synchrotron. In order to satisfy the beam power of 1 MW required for the second stage of the J-PARC in the near future, we have to increase the ion current to more than 60 mA. Therefore, we have started to develop a Cs-seeded ion source by adding an external Cs-seeding system to a J-PARC test ion source that has a structure similar to that of the J-PARC ion source except for the fact that the plasma chamber is slightly larger. As a result, a H(-) ion current of more than 70 mA was obtained from the ion source using a tungsten filament instead of a LaB(6) filament with a low arc discharge power of 15 kW (100 V, 150 A). |
20192385 | Recent operation status of Japan Proton Accelerator Research Complex H- ion source. | A cesium-free H(-) ion source driven with a LaB(6) filament is being operated at the Japan Proton Accelerator Research Complex for approximately three years without any serious trouble. In the missioning or supply runs, the ion source has been operated in two different modes such as low current mode of 5 mA and high current mode of 30 mA. The total interruption time during the runs due to the ion source failure is approximately 50 h, which correspond to the ion source availability of 99%. After a long-term operation, the surface of the filament and the plasma electrode e discolored with dark partially. The result of surface analysis with field emission scanning electron microscope showed that most of the dark material is formed with boron. At the beam test performed in the interval of the run, we demonstrated that the H(-) current increased by miniaturizing the LaB(6) filament. |
20192387 | A survey of optimal filament shape in a Japan Proton Accelerator Research Complex H- ion source. | Dependence of various shapes of lanthanum hexaboride (LaB(6)) filaments on H(-) ion currents (I_H(-)'s) was examined by using the first Japan Proton Accelerator Research Complex (J-PARC) test ion source. It is almost the same with the J-PARC H(-) ion source (J-PARC-IS) except for the maximum arc current (290 A instead of 400 A). An I_H(-) of 35.2 mA was extracted by using a cylindrical double-spiral LaB(6) filament with a diameter of 29.5 mm and a length of 35.5 mm, which is the same one used in J-PARC-IS. It increased to 43.4 mA with a flat triple-hairpin LaB(6) filament. The I_H(-) is considered to be increased by the enlargement of the high density plasma region near the plasma electrode aperture and the reduction of the LaB(6) filament unemission area located in the high density plasma region. |
20192388 | An innovative high-power constant-current pulsed-arc power-supply for a high-density pulsed-arc-plasma ion-source using a LaB6-filament. | An innovative high-power constant-current (CC) pulsed-arc (PA) power-supply (PS) indispensable for a high-density PA plasma ion-source using a lanthanum hexaboride (LaB(6)) filament was devised bining a constant-voltage (CV) PA-PS, which posed of an insulated gate bipolar transistor (IGBT) switch, a CV direct-current (dc) PS and a 270 mF capacitor with a CC-PA-PS, which posed of an IGBT-switch, a CC-dc-PS and a 400 microH inductor, through the inductor. The hybrid-CC-PA-PS succeeded in producing a flat arc-pulse with a peak power of 56 kW (400 A x 140 V) and a duty factor of more than 1.5% (600 micros x 25 Hz) for Japan Proton Accelerator Research Complex (J-PARC) H(-) ion-source stably. It also succeeded in shortening the 99% rising-time of the arc-pulse-current to about 20 micros and tilting up or down the arc-pulse-current arbitrarily and almost linearly by changing the setting voltage of its CV-dc-PS. |
20192389 | Interesting experimental results in Japan Proton Accelerator Research Complex H- ion-source development (invited). | The following interesting experimental results observed in Japan Proton Accelerator Research Complex (J-PARC) H(-) ion-source developments are reviewed. It was proven that almost all of H(-) ions were produced with surface reactions in cesium (Cs)-free J-PARC H(-) ion-sources. The world's most intense class H(-) ion current of 38 mA in Cs-free ion sources for a high-energy linac was attained by an optimal shape and high temperature of the plasma electrode (PE), usage of a lanthanum hexaboride (LaB(6)) filament, and a newly devised high-power constant-current pulsed-arc power supply indispensable for it. It was also proven that the H(-) ion current could be increased to more than 40 mA by optimizing LaB(6)-filament shape. The surface elemental analysis of the PE after operation with a LaB(6)-filament showed that it was coated by boron (B) 95.5%, lanthanum (La) 2.5%, and oxygen (O) 1.9%. The H(-) ion current decreased by about 20% when a tungsten (W) filament was used instead of a LaB(6)-filament. The H(-) ion current could not be increased by seeding cesium (Cs) if the LaB(6)-filament was used. On the other hand, it was increased to more than 70 mA with much lower arc current of 150 A if Cs was seeded when a W-filament was used. |
20192390 | The front end test stand high performance H- ion source at Rutherford Appleton Laboratory. | The aim of the front end test stand (FETS) project is to demonstrate that chopped low energy beams of high quality can be produced. FETS consists of a 60 mA Penning Surface Plasma Ion Source, a three solenoid low energy beam transport, a 3 MeV radio frequency quadrupole, a chopper, and prehensive suite of diagnostics. This paper details the design and initial performance of the ion source and the laser profile measurement system. Beam current, profile, and emittance measurements are shown for different operating conditions. |
20192391 | Finite element thermal study of the Linac4 plasma generator. | The temperature distribution and heat flow at equilibrium of the plasma generator of the rf-powered noncesiated Linac4 H(-) ion source have been studied with a finite element model. It is shown that the equilibrium temperatures obtained in the Linac4 nominal operation mode (100 kW rf power, 2 Hz repetition rate, and 0.4 ms pulse duration) are within material specifications except for the magnet cage, where a redesign may be necessary. To assess the upgrade of the Linac4 source for operation in the high-power operation mode of the Superconducting Proton Linac (SPL), an extrapolation of the heat load toward 100 kW rf power, 50 Hz repetition rate, and 0.4 ms pulse duration has been performed. The results indicate that a significant improvement of the source cooling is required to allow for operation in the high-power mode of SPL. |
20192393 | Aberration of a negative ion beam caused by space charge effect. | Aberrations are inevitable when the charged particle beams are extracted, accelerated, transmitted, and focused with electrostatic and magnetic fields. In this study, we investigate the aberration of a negative ion accelerator for a neutral beam injector theoretically, especially the spherical aberration caused by the negative ion beam expansion due to the space charge effect. The negative ion current density profiles with the spherical aberration pared with those without the spherical aberration. It is found that the negative ion current density profiles in a log scale are tailed due to the spherical aberration. |
20192392 | High duty factor plasma generator for CERN's Superconducting Proton Linac. | CERN's Linac4 is a 160 MeV linear accelerator currently under construction. It will inject negatively charged hydrogen ions into CERN's PS-Booster. Its ion source is a noncesiated rf driven H(-) volume source directly inspired from the one of DESY and is aimed to deliver pulses of 80 mA of H(-) during 0.4 ms at a 2 Hz repetition rate. The Superconducting Proton Linac (SPL) project is part of the luminosity upgrade of the Large Hadron Collider. It consists of an extension of Linac4 up to 5 GeV and is foreseen to deliver protons to a future 50 GeV synchrotron (PS2). For the SPL high power option (HP-SPL), the ion source would deliver pulses of 80 mA of H(-) during 1.2 ms and operate at a 50 Hz repetition rate. This significant upgrade motivates the design of the new water cooled plasma generator presented in this paper. Its engineering is based on the results of a finite element thermal study of the Linac4 H(-) plasma generator that identified ponents and thermal barriers. A cooling system is proposed which achieves the required heat dissipation and maintains the original functionality. Materials with higher thermal conductivity are selected and, wherever possible, thermal barriers resulting from low pressure contacts are removed by brazing metals on insulators. The AlN plasma chamber cooling circuit is inspired from the approach chosen for the cesiated high duty factor rf H(-) source operating at SNS. |
20192394 | rf improvements for Spallation Neutron Source H- ion source. | The Spallation Neutron Source at Oak Ridge National Laboratory is ramping up the accelerated proton beam power to 1.4 MW and just reached 1 MW. The rf-driven multicusp ion source that originates from the Lawrence Berkeley National Laboratory has been delivering approximately 38 mA H(-) beam in the linac at 60 Hz, 0.9 ms. To improve availability, a rf-driven external antenna multicusp ion source with a water-cooled ceramic aluminum nitride (AlN) plasma chamber is developed. Computer modeling and simulations have been made to analyze and optimize the rf performance of the new ion source. Operational statistics and test runs with up to 56 mA medium energy beam transport beam current identify the 2 MHz rf system as a limiting factor in the system availability and beam production. Plasma ignition system is under development by using a separate 13 MHz system. To improve the availability of the rf power system with easier maintenance, we tested a 70 kV isolation transformer for the 80 kW, 6% duty cycle 2 MHz amplifier to power the ion source from a grounded solid-state amplifier. |
20192396 | The continued development of the Spallation Neutron Source external antenna H- ion source. | The U.S. Spallation Neutron Source (SNS) is an accelerator-based, pulsed neutron-scattering facility, currently in the process of ramping up neutron production. In order to ensure that the SNS will meet its mitments as well as provide for future facility upgrades with high reliability, we are developing a rf-driven, H(-) ion source based on a water-cooled, ceramic aluminum nitride (AlN) plasma chamber. To date, early versions of this source have delivered up to 42 mA to the SNS front end and unanalyzed beam currents up to approximately 100 mA (60 Hz, 1 ms) to the ion source test stand. This source was operated on the SNS accelerator from February to April 2009 and produced approximately 35 mA (beam current required by the ramp up plan) with availability of approximately 97%. During this run several ion source failures identified reliability issues, which must be addressed before the source re-enters production: plasma ignition, antenna lifetime, magnet cooling, and cooling jacket integrity. This report discusses these issues, details proposed engineering solutions, and notes progress to date. |
20192395 | Computer simulations for rf design of a Spallation Neutron Source external antenna H- ion source. | Electromagnetic modeling of the multicusp external antenna H(-) ion source for the Spallation Neutron Source (SNS) has been performed in order to optimize high-power performance. During development of the SNS external antenna ion source, antenna failures due to high voltage and multicusp magnet holder rf heating concerns under stressful operating conditions led to rf characteristics analysis. In rf simulations, the plasma was modeled as an equivalent lossy metal by defining conductivity as sigma. Insulation designs along with material selections such as ferrite and Teflon could be included in puter simulations pare antenna gap potentials, surface power dissipations, and input impedance at the operating frequencies, 2 and 13.56 MHz. Further modeling and design improvements are outlined in the conclusion. |
20192397 | Modeling of the rf discharge initiation in a negative ion source. | The maintenance free rf ion source is expected to be one of the most promising candidates for the negative ion sources of plasma heating for future fusion reactors. As an alternative to the arc-discharge sources, the rf negative ion sources have been developed for H(-) production. In order to make clear the condition for the discharge initiation of the rf source, we are developing a numerical model using the finite difference time domain Monte Carlo method to analyze the electron energy distribution function in rf field. The numerical result shows that the discharge is not successfully initiated due to the wall loss unless the wall potential is considered. More self-consistent model including ion dynamics to evaluate the wall potential and the electron loss at the wall will be needed in the future. |
20192398 | Ramping up the Spallation Neutron Source beam power with the H- source using 0 mg Cs/day. | This paper describes the ramp up of the beam power for the Spallation Neutron Source by ramping up the pulse length, the repetition rate, and the beam current emerging from the H(-) source. Starting out with low repetition rates (< or = 10 Hz) and short pulse lengths (< or = 0.2 ms), the H(-) source and low-energy beam transport delivered from Lawrence Berkeley National Laboratory exceeded the requirements with almost perfect availability. This paper discusses the modifications that were required to exceed 0.2 ms pulse length and 0.2% duty factor with acceptable availability and performance. Currently, the source is supporting neutron production at 1 MW with 38 mA linac beam current at 60 Hz and 0.9 ms pulse length. The pulse length will be increased to approximately 1.1 ms to meet the requirements for neutron production with a power between 1 and 1.4 MW. A medium-energy beam transport (MEBT) beam current of 46 mA with a 5.4% duty factor has been demonstrated for 32 h. A 56 mA MEBT beam current with a 4.1% duty factor has been demonstrated for 20 min at the conclusion of a 12-day production run. This is close to the 59 mA needed for 3 MW neutron productions. Also notable is the Cs(2)CrO(4) cesium system, which dispenses approximately 10 mg of Cs during the startup of the ion source, sufficient for producing the required 38 mA for 4 weeks without significant degradation. |
20192399 | First operation of the charge-breeder electron-cyclotron-resonance ion source at the Texas A&M Cyclotron Institute. | The 14.5 GHz electron-cyclotron-resonance ion source (ECRIS) designed and fabricated specifically for charge breeding has been installed at the Texas A&M University Cyclotron Institute for use in the institute's ongoing radioactive-ion-beam upgrade. The initial testing of the source has just begun with magnetic analysis of the ECRIS beam. The source has only been conditioning for a brief time at low microwave power, and it is continuing to improve. After the source has been conditioned and characterized, charge-breeding trials with stable beams from a singly ionizing source will begin. |
20192400 | Development of radioactive ion beam production systems for Tokai Radioactive Ion Acceleration Complex-High temperature ion source for short-lived isotopes. | We have developed a new ion source system in the isotope separator on-line at Japan Atomic Energy Agency, for separation of short-lived isotopes produced by proton-induced fission of (238)U. The ion source system is a forced electron beam induced arc discharge version E type ion source with a target container. We successfully operated this system at 2000 degrees C as a result of reductions in volume of the ion source and the target container, introduction of heating method by electron bombardment, and improvement to the heat shield. This new ion source system was tested using (238)U of 640 mg/cm(2) with a proton primary beam of 30 MeV, 350 nA. Release times were measured for Kr, In, and Xe. The values of release times are 2.6 s for Kr, 1.8 s for In, and 4.6 s for Xe. In this work, the ion source system enabled us to mass-separate short-lived isotopes such as (93)Kr(T(1/2)=1.286 s), (129)In(T(1/2)=0.61 s), and (141)Xe(T(1/2)=1.73 s) with intensity of 10(3) ions/s. |
20192401 | Charge state breeding for the acceleration of radioactive ions at TRIUMF. | A 14.5 GHz electron cyclotron resonance ion source (PHOENIX from Pantechnik) has been set up at the Isotope Separation and ACceleration (ISAC) facility at TRIUMF for the charge state breeding of radioactive ions. After extensive testing and optimization on a test bench it has been moved on-line and put into operation. During a first test in 2008 a beam of (80)Rb(14+) was successfully created from (80)Rb(1+) and accelerated by the ISAC postaccelerator. Further tests with different stable and radioactive isotopes from the ISAC on-line sources and from a test source with stable Cs have been carried out. Until now an efficiency of 1.4% for (124)Cs(20+) has been obtained. |
20192403 | Integrated modeling of electron cyclotron resonance ion sources and charge breeders with GEM, MCBC, and IonEx. | A numerical toolset to help in understanding physical processes in the electron cyclotron resonance charge breeder (ECRCB) and further to help optimization and design of current and future machines is presented. The toolset consists of three modules (Monte Carlo charge breeding code, generalized electron cyclotron resonance ion source modeling, and ion extraction), each modeling different processes occurring in the ECRCB from beam injection to extraction. The toolset provides qualitative study, such as parameter studies, and scaling of the operation, and physical understanding in the ECRCB. The methodology and a sample integrated modeling are presented. |
20192402 | Direct 1+ --> N+ conversion of stable alkali ions using an electron cyclotron resonance ion source. | The production of radioactive ions using the Isotope Separation On-Line method gives rise, in most cases, to singly charged ions. In order to perform experiments with postaccelerated radioactive ion beams, these ions have to be multicharged. We describe here a pact design for a charge breeder that will be coupled to the production target of SPIRAL1 at GANIL. We present recent results obtained offline with stable alkali ions (Na, K, Rb, and Cs) on the SIRa test bench. Particularly, 1(+) to N(+) conversion efficiencies and conversion times are presented. Several points have been identified for the improvements of the present performances. |
20192405 | Results with the electron cyclotron resonance charge breeder for the 252Cf fission source project (Californium Rare Ion Breeder Upgrade) at Argonne Tandem Linac Accelerator System. | The construction of the Californium Rare Ion Breeder Upgrade, a new radioactive beam facility for the Argonne Tandem Linac Accelerator System (ATLAS), is pletion. The facility will use fission fragments from a 1 Ci (252)Cf source; thermalized and collected into a low-energy particle beam by a helium gas catcher. In order to reaccelerate these beams, an existing ATLAS electron cyclotron resonance (ECR) ion source was redesigned to function as an ECR charge breeder. Thus far, the charge breeder has been tested with stable beams of rubidium and cesium achieving charge breeding efficiencies of 9.7% into (85)Rb(17+) and 2.9% into (133)Cs(20+). |
20192404 | Development of high efficiency Versatile Arc Discharge Ion Source at CERN ISOLDE. | We report here recent developments of Forced Electron Beam Induced Arc Discharge (FEBIAD) ion sources at the ISOLDE radioactive ion beam facility, hosted at the European Organization for Nuclear Research (CERN). As a result of the propositions to improve the ionization efficiency, two FEBIAD prototypes have been produced and successfully tested in 2008. Off-line studies showed that the 1+ ionization efficiencies for noble gases are 5-20 times larger than with the standard ISOLDE FEBIAD ion sources and reach 60% for radon, which allowed the identification at ISOLDE of (229)Rn, an isotope that had never previously been observed in the laboratory. A factor of 3 increase is also expected for the ionization efficiency of the other elements. The experimental and theoretical methodology is presented. The theoretical model, which gives precise insights on the processes affecting the ionization, is used to design optimal sources (grouped under the name of VADIS--Versatile Arc Discharge Ion Source) for the different chemical classes of the produced isotopes, as already demonstrated for the noble gases. |
20192406 | Latest developments at GANIL for stable and radioactive ion beam production. | In the frame of the SPIRAL II (Système de Production d'Ions Radioactifs Accélérés en Ligne Partie II) project, several developments of stable and radioactive ion production systems have been started up. In parallel, GANIL has the ambition to preserve the existing stable and radioactive beams and also to increase its range by offering new ones. In order to identify the best directions for this development, a new group called GANISOL has been formed. Its preliminary conclusions and the latest developments at GANIL are presented. |
20192407 | GISELE: a resonant ionization laser ion source for the production of radioactive ions at GANIL. | SPIRAL2 is the new project under construction at GANIL to produce radioactive ion beams and in particular neutron rich ion beams. For the past 10 yr SPIRAL1 at GANIL has been delivering accelerated radioactive ion beams of gases. Both facilities now need to extend the range of radioactive ion beams produced to condensable elements. For that purpose, a resonant ionization laser ion source, funded by the French Research National Agency, is under development at GANIL, in collaboration with IPN Orsay, University of Mainz (Germany) and TRIUMF, Vancouver (Canada). A description of this project called GISELE (GANIL Ion Source using Electron Laser Excitation) is presented. |
20192408 | Long pulse H- ion beam acceleration in MeV accelerator. | A multiaperture multigrid accelerator called "MeV accelerator" has been developed for neutral beam injection system of international thermonuclear experimental reactor. In the present work, long pulse H(-) ion beam acceleration was performed by the MeV accelerator equipped with new water-cooled grids. At present, the pulse length was extended to 5 s for the beams of 750 keV, 221 mA, and 10 s for the beams of 600 keV, 158 mA. Energy density, defined as products of beam energy (keV), current (mA), and pulse (s) divided by aperture area (m(2)), increased more than one order of magnitude pared with original MeV accelerator without water cooling in its grids. At higher energy and current, the grid was melted by beam deflection. Due to this grid melting, breakdowns occurred between the grids, and hence, the pulse length was limited. Beam deflection will pensated by aperture displacement in next experiment. |
20192409 | Fundamental experiments on evaporation of cesium in ion sources. | Basic experiments are carried out to study the cesium evaporation and desorption from surfaces at different temperatures in an environment, which is very close to the conditions of negative hydrogen ion sources for fusion applications: in a vacuum base pressure of 10(-5) mbar and in a hydrogen plasma in the Pa-range. Several diagnostic techniques such as emission and absorption spectroscopy, a surface ionization detector, and a quartz-microbalance have been utilized to determine the cesium densities, evaporation and desorption rates. The work function of a cesiated surface measured by the photoelectric effect degrades with increasing plasma-off time. Impurities and pounds are detected by a residual mass analyzer. |
20192410 | Analysis of secondary particle behavior in multiaperture, multigrid accelerator for the ITER neutral beam injector. | Heat load on acceleration grids by secondary particles such as electrons, neutrals, and positive ions, is a key issue for long pulse acceleration of negative ion beams. Complicated behaviors of the secondary particles in multiaperture, multigrid (MAMuG) accelerator have been analyzed using electrostatic accelerator Monte Carlo code. The analytical result pared to experimental one obtained in a long pulse operation of a MeV accelerator, of which second acceleration grid (A2G) was removed for simplification of structure. The analytical results show that relatively high heat load on the third acceleration grid (A3G) since stripped electrons were deposited mainly on A3G. This heat load on the A3G can be suppressed by installing the A2G. Thus, capability of MAMuG accelerator is demonstrated for suppression of heat load due to secondary particles by the intermediate grids. |
20192411 | Operation and upgrade of diagnostic neutral beam injector RUDI at TEXTOR tokamak. | The status and the executing modernization of RUssian Diagnostic Injector (RUDI) are described. The ion source consists of arc plasma emitter and multiaperture four-electrode ion optical system. The present ion optical system with round beamlets is to be replaced by new slit apertures system for the reducing beam angular divergence in one direction. Due to enlarged dimensions and transparency of new ion optical system the extracted ion beam current will be by 50% increased. For the extension of beam pulse duration from 4 s to 8-10 s an optimized metal-ceramic arc-discharge channel is introduced. In the paper, the optical measurements results of beam parameters, including the profile of species distribution, scanned by custom-built multichannel spectroscope, are also presented. |
20192412 | The study of helicon plasma source. | Helicon plasma source is known as efficient generator of uniform and high density plasma. A helicon plasma source was developed for investigation of plasma neutralization and plasma lens in the Institute of Modern Physics in China. In this paper, the characteristics of helicon plasma have been studied by using Langmuir four-probe and a high argon plasma density up to 3.9x10(13) cm(-3) have been achieved with the Nagoya type III antenna at the conditions of the magnetic intensity of 200 G, working gas pressure of 2.8x10(-3) Pa, and rf power of 1200 W with a frequency of 27.12 MHz. In the experiment, the important phenomena have been found: for a given magnetic induction intensity, the plasma density became greater with the increase in rf power and tended to saturation, and the helicon mode appeared at the rf power between 200 and 400 W. |
20192413 | Numerical simulation for the accelerator of the KSTAR neutral beam ion source. | Recent experiments with a prototype long-pulse, high-current ion source being developed for the neutral beam injection system of the Korea Superconducting Tokamak Advanced Research have shown that the accelerator grid assembly needs a further upgrade to achieve the final goal of 120keV/65A for the deuterium ion beam. The accelerator upgrade concept was determined theoretically by simulations using the IGUN code. The simulation study was focused on finding parameter sets that raise the optimum perveance as large as possible and reduce the beam divergence as low as possible. From the simulation results, it was concluded that it is possible to achieve this goal by sliming the plasma grid (G1), shortening the second gap (G2-G3), and adjusting the G2 voltage ratio. |
20192414 | Radio frequency ion source operated with field effect transistor based radio frequency system. | Characteristics of radio frequency (RF) plasma production are investigated using a field effect transistor inverter power supply as an RF wave source. With the frequency of around 0.3 MHz, an electron density over 10(18) m(-3) is produced in argon plasma. Although lower densities are obtained in hydrogen plasma, it drastically increased up to 5x10(18) m(-3) with an axial magnetic field of around 100 G applied in the driver region. Effects of the magnetic field and gas pressure are investigated in the RF produced plasma with the frequency of several hundred kilohertz. |
20192415 | Characterization of 1 MW, 40 keV, 1 s neutral beam for plasma heating. | Neutral beam with geometrical focusing for plasma heating in moderate-size plasma devices has been developed in Budker Institute of Nuclear Physics, Novosibirsk. When operated with hydrogen, the neutral beam power is 1 MW, pulse duration is 1 s, beam energy is 40 keV, and angular divergence is 1.2 degrees. Initial ion beam is extracted and accelerated by triode multiapertures ion-optical system. To produce 1 MW neutral beam, about 40 A proton current is extracted with nominal current density of 320 mA/cm(2). Ion-optical system has 200 mm diameter grids with 44% transparency. The grids have inertia cooling and heat is removed between the pulses by water flowing in channels placed on periphery of the grids. A plasma emitter for ion extraction is produced by rf-plasma box. Ion species mix of rf plasma source amounts to 70%, 20%, and 10% of H(+), H(2)(+), and H(3)(+) ions, respectively, by current. Heavy impurities contribute less than 0.3%. |
20192417 | Long pulse H- beam extraction with a rf driven ion source on a high power level. | IPP Garching is investigating the applicability of rf driven negative ion sources for the neutral beam injection of International Thermonuclear Experimental Reactor. The setup of the tested source was improved to enable long pulses up to 100 kW rf power. The efficiency of negative ion production decreases at high power. The extracted H(-) currents as well as the symmetry of the plasma density close to the plasma grid and of the beam divergence depend on the magnetic filter field. The pulse duration is limited by the increase in coextracted electrons, which depends on the rf power and the caesium conditions on the plasma grid. |
20192416 | Erosion of accel grids of ion engine due to sputtering. | The erosion rates of extraction electrodes of ion sources due to ion beam irradiation are largely affected by amount of projectiles retained in the electrodes. A Monte Carlo simulation code ACAT has been used to calculate sputtering yields and reflection coefficients by simulating the accumulation effect of projectiles in a target material. The results for Xe projectiles-C bination have indicated that both sputtering yields and reflection coefficients are largely enhanced by Xe retention, particularly at larger incident angle for the surface normal with low incident energy. |
20192418 | Investigation of fringe plasma parameters on a high power rf driven ion source. | It has been observed that there are differences between the pensated Langmuir probes installed in the upper and lower areas of the rf driven H(-) sources at IPP Garching. The two probes often had substantially different floating potentials or ion saturation currents. In an effort to understand the reasons for these differences a Langmuir probe analysis system was used on the probes to collect the full current voltage characteristic. The results show what is likely the formation of an ion-ion plasma. The paper shows the effect of beam extraction and the presence of caesium on the probe characteristics. |
20192419 | Analyses of high power negative ion accelerators for ITER neutral beam injector (invited). | In JAEA, research and developments to realize high power accelerator (1 MeV, 40 AD(-) ion beams for 3600 s) for ITER have been carried out experimentally and numerically utilizing a five stage MAMuG (Multiaperture, Multigrid) accelerator. In this paper, the extension of the gap length, which is required to improve the voltage holding capability, is examined in two dimensional beam optics analyses and also from view point of stripping loss of ions. In order to suppress excess power loadings due to the direct interception of negative ions, which is issued in long pulse tests, the beamlet deflection is analyzed in three dimensional multibeamlet analyses. The necessary modifications shown above are applied to the MAMuG accelerator ing long pulse tests in JAEA and ITER. |
20192420 | Negative ion source development for fusion application (invited). | Giant negative ion sources, producing high-current of several tens amps with high energy of several hundreds keV to 1 MeV, are required for a neutral beam injector (NBI) in a fusion device. The giant negative ion sources are cesium-seeded plasma sources, in which the negative ions are produced on the cesium-covered surface. Their characteristic features are discussed with the views of large-volume plasma production, large-area beam acceleration, and high-voltage dc holding. The international thermonuclear experimental reactor NBI employs a 1 MeV-40 A of deuterium negative ion source, and intensive development programs for the rf-driven source plasma production and the multistage electrostatic acceleration are in progress, including the long pulse operation for 3600 s. Present status of the development, as well as the achievements of the giant negative ion sources in the working injectors, is also summarized. |
20192421 | Fine-structure characteristics in the emittance images of a strongly focusing He+ beam. | The phase space distribution of a strongly focused He(+) ion beam source equipped with concave multiaperture electrodes was measured using a pepper-pot plate and a Kapton foil. The substructure of 301 merging He beamlets was clearly observed on a footprint of pepper-pot hole at the beam waist, where the beam density was 500 mA/cm(2). The position and the width of each beamlet substructure show the effect of interference of beamlets with surrounding one. |
20192422 | Characteristics of 80 keV positive ion source for Large Helical Device. | An additional beamline, BL5, equipped with four positive ion sources will be installed on Large Helical Device (LHD) in 2010. The performance of an ion source which generates 80 keV deuterium and 60 keV hydrogen beams was investigated. The structure of the ion source is based on that of a BL4 ion source on LHD. The main differences between the ion sources for the BL4 and BL5 are the acceleration voltages and the materials of plasma electrodes: copper and molybdenum, respectively. The molybdenum plasma electrode for BL5 has better performance than the copper plasma electrode of BL4. The integrated performance of the ion source for BL5 reached a value equivalent to approximately 58 A in the beam current of hydrogen positive ion at 60 keV in the beam energy. |
20192423 | Beamlet characteristics in the accelerator with multislot grounded grid. | Characteristics of multibeamlets are investigated by means of beamlet monitoring technique. The beamlets are extracted from an accelerator with multislot grounded grid and the profiles are observed as infrared images of temperature distributions on a cold isostatic pressed graphite plate exposed by H-beamlets. The optimal horizontal and vertical divergence angles of single beamlet are estimated at 4.1 and 6.1 mrad, respectively. |
20192425 | Sources of polyatomic ions of organic liquids. | We have developed two types of liquid ion sources, one of which was a polyatomic ion source using liquid organic materials with a high-vapor pressure. Liquid materials such as octane and ethanol could be heated up to a maximum temperature of 100 degrees C, and the vapors were introduced into an ion source. They were ionized by an electron bombardment method and extracted from the ionizer. The ion current obtained at an extraction voltage of 2 kV was 230 microA for octane and several fragment ions such as alkyl ions were produced. On the other hand, another type of polyatomic ion source using alkyl naphthalene mixed with ionic liquid such as imidazolium dicyanamide has been developed. Instead of the electron bombardment method, a high-electric field method was used for the ion-emission from a sharp tip, because the vapor pressure of the liquid materials was relatively low. The threshold voltage was approximately 4.5 kV and the ion current of approximately 250 nA was obtained at an extraction voltage of 9.5 kV. |
20192424 | General design of the International Fusion Materials Irradiation Facility deuteron injector: source and beam line. | In the framework of the International Fusion Materials Irradiation Facility-Engineering Validation and Engineering Design Activities (IFMIF-EVEDA) project, CEA/IRFU is in charge of the design and realization of the 140 mA cw deuteron Injector. The electron cyclotron resonance ion source operates at 2.45 GHz and a 4 electrode extraction system has been chosen. A 2 solenoid beam line, together with a high space pensation have been optimized for a proper beam injection in the 175 MHz radio frequency quadrupole. The injector will be tested with proton and deuteron beam production either in pulsed mode or in cw mode on the CEA-Saclay site before to be shipped to Japan. Special attention was paid to neutron emission due to (d,D) reaction. In this paper, the general IFMIF Injector design is reported, pointing out beam dynamics, radioprotection, diagnostics, and mechanical aspects. |
20192426 | Boron ion source based on planar magnetron discharge in self-sputtering mode. | An ion source based on a planar magnetron sputtering device with thermally isolated target has been designed and demonstrated. For a boron sputtering target, high target temperature is required because boron has low electrical conductivity at room temperature, increasing with temperature. The target is well-insulated thermally and can be heated by an initial low-current, high-voltage discharge mode. A discharge power of 16 W was adequate to attain the required surface temperature (400 degrees C), followed by transition of the discharge to a high-current, low-voltage mode for which the magnetron enters a self-sputtering operational mode. Beam analysis was performed with a time-of-flight system; the maximum boron ion fraction in the beam is greater than 99%, and the mean boron ion fraction, time-integrated over the whole pulse length, is about 95%. We have plans to make the ion source steady state and test with a bending magnet. This kind of boron ion source could petitive to conventional boron ion sources that pounds such as BF(3), and could be useful for semiconductor industry application. |
20192428 | Self-heated hollow cathode discharge system for charged particle sources and plasma generators. | This paper presents the results of experimental studies of a new design of discharge system using a self-heated hollow cathode. The discharge system offers certain advantages that are attractive for use in high-dose ion implantation, plasma generators, and plasma electron sources. |
20192427 | Broad-beam high-current dc ion source based on a two-stage glow discharge plasma. | We have designed, made, and demonstrated a broad-beam, dc, ion source based on a two-stage, hollow-cathode, and glow discharges plasma. The first-stage discharge (auxiliary discharge) produces electrons that are injected into the cathode cavity of a second-stage discharge (main discharge). The electron injection causes a decrease in the required operating pressure of the main discharge down to 0.05 mTorr and a decrease in required operating voltage down to about 50 V. The decrease in operating voltage of the main discharge leads to a decrease in the fraction of impurity ions in the ion beam extracted from the main gas discharge plasma to less than 0.2%. Another feature of the source is a single-grid accelerating system in which the ion accelerating voltage is applied between the plasma itself and the grid electrode. The source has produced steady-state Ar, O, and N ion beams of about 14 cm diameter and current of more than 2 A at an accelerating voltage of up to 2 kV. |
20192429 | A self-sputtering ion source: a new approach to quiescent metal ion beams. | A new metal ion source is presented based on sustained self-sputtering plasma in a magnetron discharge. Metals exhibiting high self-sputtering yield such as Cu, Ag, Zn, and Bi can be used in a high-power impulse magnetron sputtering discharge such that the plasma almost exclusively contains singly charged metal ions of the target material. The plasma and extracted ion beam are quiescent. The ion beams consist mostly of singly charged ions with a space-charge limited current density which reached about 10 mA/cm(2) at an extraction voltage of 45 kV and a first gap spacing of 12 mm. |
20192430 | Gridless, very low energy, high-current, gaseous ion source. | We have made and tested a very low energy gaseous ion source in which the plasma is established by a gaseous discharge with electron injection in an axially diverging magnetic field. A constricted arc with hidden cathode spot is used as the electron emitter (first stage of the discharge). The electron flux so formed is filtered by a judiciously shaped electrode to remove macroparticles (cathode debris from the cathode spot) from the cathode material as well as atoms and ions. The anode of the emitter discharge is a mesh, which also serves as cathode of the second stage of the discharge, providing a high electron current that is injected into the magnetic field region where the operating gas is efficiently ionized. In this discharge configuration, an electric field is formed in the ion generation region, accelerating gas ions to energy of several eV in a direction away from the source, without the use of a gridded acceleration system. Our measurements indicate that an argon ion beam is formed with an energy of several eV and current up to 2.5 A. The discharge voltage is kept at less than 20 V, to keep below ion sputtering threshold for cathode material, a feature which along with filtering of the injected electron flow, results in extremely low contamination of the generated ion flow. |
20192431 | Review of polarized ion sources (invited). | Recent progress in polarized ion sources development is reviewed. New techniques for production of polarized H(-) ion (proton), D(-) (D(+)), and (3)He(++) ion beams are discussed. Feasibility studies of these techniques are in progress at BNL and other laboratories. Polarized deuteron beams will be required for the polarization program at the Dubna Nuclotron and at the deuteron electric dipole moment experiment at BNL. Experiments with polarized (3)He(++) ion beams are a part of the experimental program at the future electron ion collider. |
20192433 | Ion beam oscillation due to fluctuation of a hot filament driven magnetized plasma. | Ion beam current extracted from a modified Bernas type ion source occasionally exhibits an oscillation at a frequency of several 100 kHz. Increase in the strength of a linear magnetic field induced to the ion source has either decreased or increased the frequency of this oscillation. The frequency showed an increase in proportion to the ion extraction voltage when the frequency decreased with increasing magnetic field. The change of extraction voltage did not affect the frequency when the frequency increased with the increasing magnetic field. Mechanisms causing these oscillations of an ion beam had been investigated. |
20192432 | Enhancement in ion beam current with layered-glows in a constricted dc plasma ion source. | High current mode has been discovered and investigated in a constricted dc plasma ion source. As discharge currents exceed a certain threshold, voltage to sustain the constricted dc plasma suddenly falls down to almost half of the value. In this sense, constricted dc plasmas can be sustained at much higher current than in conventional mode operation at a fixed discharge voltage. Phenomenally, several discrete layered-glows are created between an anode glow and a cathode glow. The layers are thin and divided by dark spaces where charged particles can be accelerated. In this high current mode, ion beam current density is about 100 times higher than in conventional mode at the same voltage. It is noteworthy that lower gas pressure is desirable to sustain the layered-glow mode, which is also profitable for ion source in terms of differential pumping. Ion current density exceeds 300 mA/cm(2) at low discharge power of 175 W where ion density of plasma ball is estimated to be over 3.7x10(12) cm(-3). |
20192434 | High-intensity ion sources for accelerators with emphasis on H- beam formation and transport (invited). | This paper lays out the fundamental working principles of a variety of high-current ion sources for accelerators in a tutorial manner, and gives examples of specific source types such as dc discharge-driven and rf-driven multicusp sources, Penning-type, and electron cyclotron resonance-based sources while discussing those principles, pointing out general performance limits as well as the performance parameters of specific sources. Laser-based, two-chamber, and surface-ionization sources are briefly mentioned. Main aspects of this review are particle feed, ionization mechanism, beam formation, and beam transport. Issues seen with beam formation and low-energy transport of negative hydrogen-ion beams are treated in detail. |
20192436 | Review on high current 2.45 GHz electron cyclotron resonance sources (invited). | The suitable source for the production of intense beams for high power accelerators must obey to the request of high brightness, stability, and reliability. The 2.45 GHz off-resonance microwave discharge sources are the ideal device to generate the requested beams, as they produce multimilliampere beams of protons, deuterons, and monocharged ions, remaining stable for several weeks without maintenance. A description of different technical designs will be given, analyzing their strength, and weakness, with regard to the extraction system and low energy beam transport line, as the presence of beam halo is detrimental for the accelerator. |
20192435 | Radio frequency-driven proton source with a back-streaming electron dump. | This article describes an rf ion source with a back-streaming electron dump. A quartz tube, brazed to a metal plug at one end, is fused in the center of a flat quartz plate. rf power (at 13.6 MHz) is coupled to generate hydrogen plasma using a planar external antenna bonded to the window. Bonding the water-cooled rf antenna to the quartz window significantly lowers its temperature. The water-cooled metal plug serves as the back-streaming electron dump. At 1800 W, the current density of extracted hydrogen ions reaches approximately 125 mA/cm(2). |
20192437 | Ultracompact/ultralow power electron cyclotron resonance ion source for multipurpose applications. | In order to drastically reduce the power consumption of a microwave ion source, we have studied some specific discharge cavity geometries in order to reduce the operating point below 1 W of microwave power (at 2.45 GHz). We show that it is possible to drive an electron cyclotron resonance ion source with a transmitter technology similar to those used for cellular phones. By the reduction in the size and of the required microwave power, we have developed a new type of ultralow cost ion sources. This microwave discharge system (called COMIC, for COmpact MIcrowave and Coaxial) can be used as a source of light, plasma or ions. We will show geometries of conductive cavities where it is possible, in a 20 mm diameter chamber, to reduce the ignition of the plasma below 100 mW and define typical operating points around 5 W. Inside a simple vacuum chamber it is easy to place the source and its extraction system anywhere and fully under vacuum. In that case, current densities from 0.1 to 10 mA/cm(2) (Ar, extraction 4 mm, 1 mAe, 20 kV) have been observed. Preliminary measurements and calculations show the possibility, with a two electrodes system, to extract beams within a low emittance. The first application for these ion sources is the ion injection for charge breeding, surface analyzing system and surface treatment. For this purpose, a very small extraction hole is used (typically 3/10 mm for a 3 microA extracted current with 2 W of HF power). Mass spectrum and emittance measurements will be presented. In these conditions, values down to 1 pi mm mrad at 15 kV (1sigma) are observed, thus very close to the ones currently observed for a surface ionization source. A major interest of this approach is the possibility to connect together several COMIC devices. We will introduce some new on-going developments such as sources for high voltage implantation platforms, fully quartz radioactive ion source at ISOLDE or large plasma generators for plasma immersion, broad or ribbon beams generation. |
20192438 | Simulations of negative ion plasma sheaths. | The need to accurately model beams of negative ions in high current sources makes reasonable to refine the simulation mesh up to fractions of the Debye length lambda(D), which is typically 0.01 mm. Even if simulations were finally possible in two space dimensions, still the role of one-dimensional (1D) model to clarify the physics of sheath and presheath structure and the stability of numerical solvers is fundamental. Here a 1D model with negative ion production from the extraction wall/grid is considered, coupled to a driver plasma which acts as an electron and proton reservoir at a variable plasma potential. A bias voltage between lateral walls and the extraction wall is also included. Particle motion is modeled with diffusion equations, also for protons; electrons are magnetized and Poisson equation is solved everywhere. The inverted sheath formation and the H(-) forward current result sensitive to bias voltage. |
20192439 | Isotopic anomaly for carbon ions in an electron cyclotron resonance ion source. | In many experiments methods were applied to increase the highly charged ion output from an electron cyclotron resonance ion source; the gas-mixing method is still generally being applied. The dominant role of the masses of the ions in the gas-mixture was apparent. Two basically differing mechanisms could to first order explain most of the observations. A significant mass effect showed up in a mixture of oxygen isotopes, the so-called oxygen anomaly; so far that effect could be explained in zeroth order only. The anomaly was observed later for nitrogen isotopes as well. In the present experiment it is shown that the anomaly also exists for carbon isotopes, where the necessity of feeding the source with pounds brings about an essential different experimental fact. |
20192440 | Influence of the electron cross-field diffusion in negative ion sources with the transverse magnetic field and the plasma-electrode bias. | The physical mechanisms involved in the extraction of H(-) ions from the negative ion source are studied with a PIC 2D3V code. The effect of a weak magnetic field transverse to the extraction direction is taken into account, along with a variable bias voltage applied on the plasma electrode (PE). In addition to previous modeling works, the electron diffusion across the magnetic field is taken into account as a simple one-dimensional random-walk process. The results show that without PE bias, the value of the diffusion coefficient has a significant influence upon the value of the extracted H(-) current. However, the value of this coefficient does not affect qualitatively the mechanism leading to the peak of extracted H(-) ion current observed for an optimum value of the PE bias. |
20192442 | Development of a laser-focused ion beam combination machine. | We have developed a laser and focused ion beam pound system to process an ponent device with an ultrafine precision minute surface structure and a micromedical device. This machine consists of an FIB and three types of lasers with an atomic force microscope. This system can fabricate decamicrometer area by laser and submicrometer area by FIB at one chuck. When processing the press mold die of a microlens array (10x10) in a glasslike carbon with a femtosecond laser, a diameter of 3.2 microm and depth of 0.43 microm are obtained. However, the surface roughness is more than Rz=0.5 microm. After this process, we finished this surface with the use of the FIB. As a result, the surface roughness is less than Rz=0.05 microm. |
20192441 | Influence of H- velocity on H- extraction probability from a negative ion source. | We investigate influence of H(-) initial transport direction and kinetic energy on H(-) extraction probability with three-dimensional Monte Carlo calculation. As a result, lower energy H(-) ions are strongly trapped by the electrical potential structure, so that initial condition of H(-) transport direction is cancelled by alignment of the electric field; thus, it has lower influence for H(-) extraction probability. Besides, the potential hill induced by the beam extraction voltage more effectively enhances H(-) extraction probability for the lower energy H(-) ions. The correlation between the magnitude of the local plasma potential near the extraction region and the mean velocity of H(-) ions in the region should determine the H(-) extraction probability from the ion source. |
20192443 | IBSIMU: a three-dimensional simulation software for charged particle optics. | A general-purpose three-dimensional (3D) simulation code IBSIMU for charged particle optics with space charge is under development at JYFL. The code was originally developed for designing a slit-beam plasma extraction and nanosecond scale chopping for pulsed neutron generator, but has been developed further and has been used for many applications. The code features a nonlinear FDM Poisson's equation solver based on fast stabilized biconjugate gradient method with ILU0 preconditioner for solving electrostatic fields. A generally accepted nonlinear plasma model is used for plasma extraction. Magnetic fields can be imported to the simulations from other programs. The particle trajectories are solved using adaptive Runge-Kutta method. Steady-state and time-dependent problems can be modeled in cylindrical coordinates, two-dimensional (slit) geometry, or full 3D. The code is used via C++ programming language for versatility but it features an interactive easy-to-use postprocessing tool for diagnosing fields and particle trajectories. The open source distribution and public documentation make the code well suited for scientific use. IBSIMU has been used for modeling the 14 GHz ECR ion source extraction and for designing a four-electrode extraction for a 2.45 GHz microwave ion source at Jyväskylä. A grid extraction has also been designed for producing large uniform beam for creating conditions similar to solar wind. The code has also been used to design a H(-) extraction with electron dumping for the Cyclotron Institute of Texas A&M University. |
20192444 | Recent advances in plasma devices based on plasma lens configuration for manipulating high-current heavy ion beams. | We describe new results of development of novel generation cylindrical plasma devices based on the electrostatic plasma lens configuration and concept of electrons magnetic insulation. The crossed electric and magnetic fields plasma lens configuration provides us with the attractive and suitable method for establishing a stable plasma discharge at low pressure. Using plasma lens configuration in this way some cost-effective plasma devices were developed for ion treatment and deposition of exotic coatings and the effective lens was first proposed for manipulating high-current beams of negatively charged particles. Here we describe operation and features of these plasma devices, and results of theoretical consideration of mechanisms determining their optimal operation conditions. |
20192445 | IONEX: a meshfree ion extraction code based on "particle in cloud of points" concept. | Ion Extraction (IONEX) is an ion extraction modeling code, developed at FAR-TECH, Inc., based on the meshless particle-in-cloud-of-points concept. IONEX self-consistently solves motion equations for ions and Poisson's equation for the electrostatic field, assuming a Boltzmann distribution for the electrons. IONEX is capable of handling multiple species and is graphical user interface-driven. The two-dimensional version is benchmarked with IGUN. The basic algorithm and sample runs are presented. |
20192446 | Study of ion beam extraction and transport from an electron cyclotron resonance ion source. | We have started an experimental and theoretical program to better understand the extraction and transport of intense multiply charged ion beams from an electron cyclotron resonance ion source (ECRIS). In this paper we present the first results of this program concerning a simple, ponent He(+) beam extracted from an ECRIS. We have calculated the ion trajectories starting from the ECRIS plasma electrode up to the image plane of the analyzing magnet taking into account space-charge effects and fringe fields. The initial phase-space distribution of the He(+) beam at the extraction aperture has been calculated with a particle-in-cell code. To check the simulations we have measured beam profiles with a viewing screen both before and after the analyzing magnet. In addition also measurements with a pepperpot emittance meter located behind the analyzing magnet have been performed. We find good agreement between these measurements and simulations showing that (i) there is a pensation of the space charge and that (ii) our analyzing magnet causes a severe increase in effective beam emittance. |
20192447 | Measurements of transverse ion beam emittance generated by high current ion sources at the GSI test injector facility HOSTI. | The first emittance measurements with a new test injector facility (HOSTI) at GSI, designed for optimization of high current beam injection scheme, are discussed. The emittance of the ion beam (88 kV, Ar(1+) ions) was investigated as a function of various parameters related to the ion source, extraction, and postacceleration systems and the optimum parameters for future low energy beam transport line are concluded. The preliminary results of the emittance measurements with superconducting solenoid are presented. The influence of the focusing strength as well as the longitudinal field shape of the solenoid on the beam emittance is described. |
20192448 | Electron cyclotron resonance plasma photos. | In order to observe and study systematically the plasma of electron cyclotron resonance (ECR) ion sources (ECRIS) we made a high number of high-resolution visible light plasma photos and movies in the ATOMKI ECRIS Laboratory. This required building the ECR ion source into an open ECR plasma device, temporarily. An 8MP digital camera was used to record photos of plasmas made from Ne, Ar, and Kr gases and from their mixtures. We studied and recorded the effect of ion source setting parameters (gas pressure, position, magnetic field, and microwave power) to the shape, color, and structure of the plasma. The analysis of the photo series gave us many qualitative and numerous valuable physical information on the nature of ECR plasmas. |
20192450 | Development of a pepper-pot device to determine the emittance of an ion beam generated by electron cyclotron resonance ion sources. | This paper describes the recent development missioning of a pepper-pot emittance meter at the Lawrence Berkeley National Laboratory (LBNL). It is based on a potassium bromide (KBr) scintillator screen bination with a charged coupled device camera. Pepper-pot scanners record the full four-dimensional transverse phase space emittances which are particularly interesting for electron cyclotron resonance ion sources. The strengths and limitations of evaluating emittances using optical pepper-pot scanners are described and systematic errors induced by the optical data acquisition system will be presented. Light yield tests of KBr exposed to different ion species and first emittance measurement data using ion beams extracted from the 6.4 GHz LBNL electron cyclotron resonance ion source are presented and discussed. |
20192449 | The injection efficiency measurement and analysis for central region model cyclotron. | At the China Institute of Atomic Energy, a central region model cyclotron has been constructed, which is dedicated for various experimental verifications to study beam properties. The design features of the ion source and injection line have already been described in other papers. We shall report here the results of the initial beam tests. A wire scanner is employed in the injection line to measure beam transverse sizes and these data can be used to fit the phase plane parameters after the ion source. Based on the beam tests results, the ion source built in 2003 has been improved recently. The improvement is mainly due to the repair of the multicusp field. From the ion source to the exit of the inflector, a transmission efficiency of 93% has been obtained for a continuous and low current input beam. It is also described here the experimental arrangement and the results. |
20192451 | Preliminary studies on space charge compensation by analyzing residual argon gas ion signals. | An experimental method is related to research the space pensation (SCC) effect in low energy intense proton beams by analyzing residual gas (RG) ion signals. The signal curves were measured with an energy spectrometer under the RG pressure from 1.2x10(-3) to 1.6x10(-2) Pa. Most of the data showed a similar trend with our theoretical predicts. From the RG ion energy spectra the potential distribution in the beam was calculated both with and without the SCC effect. Moreover, as a preliminary result, a pensating point is achieved for the low energy beam transport transmission of 40 KeV, 60 mA H(+) beam in Peking University. |
20192453 | Studies of emittance of multiply charged ions extracted from high temperature superconducting electron cyclotron resonance ion source, PKDELIS. | For the high current injector project at Inter University Accelerator Centre, a high temperature superconducting electron cyclotron resonance (ECR) ion source, PKDELIS, would provide the high charge state ions. The emittance of the ECR ion source is an important parameter to design further beam transport system and to match the acceptances of the downstream radio frequency quadrupole and drift tube linac accelerators of the high current injector. The emittance of the analyzed beam of PKDELIS ECR source has been measured utilizing the three beam size technique. A slit and two beam profile monitors positioned at fixed distances from each other were used to measure the beam size. The digitized beam profiles have been analyzed to determine the emittance of various multiply charged ions. The variation of emittance with gas mixing, ultrahigh frequency power, and extraction energy are discussed in this presentation. |
20192454 | The deuteron injector progress of the Peking University Neutron Imaging Facility project. | A deuteron radio frequency quadrupoles injector h has been developed at Peking University. A permanent magnetic electron cyclotron resonance (ECR) ion source is used in the injector system. A 50 keV 100 mA proton beam has been extracted from the ECR ion source and the measured normalized rms emittance is 0.11-0.14pi mm mrad. A deuteron beam has also been extracted at 50 kV with 83 mA total current and its emittance is less than 0.18pi mm mrad. The proton beam transmission has been investigated on a low energy beam transport test bench, and up to 93% transmission can be reached. The new injector with two solenoids has been designed and is being constructed. All the development results will be presented in this paper. |
20192455 | Upgrade of the extraction system of permanent magnet electron cyclotron resonance ion source. | A set of new ion extraction electrodes have been designed for the permanent magnetic electron cyclotron resonance ion source at Peking University to improve beam quality and transmission. PBGUNS has been used to optimize the extraction electrodes and simulate the beam behavior at the extraction region. The experiments showed that with the new system, the beam half divergence angle can be less than 40 mrad and the normalized rms emittance is about 0.13pi mm mrad when the extracted current is 100 mA at 50 keV in pulse mode. The voltage of the suppression electrode has great effect on beam divergence. The effect of the microwave power and gas flow is also studied. |
20192456 | Laser plasma in a magnetic field. | Laser ion source (LIS) is a candidate among various heavy ion sources. A high density plasma produced by Nd:yttrium aluminum garnet laser with drift velocity realizes high current and high charge state ion beams. In order to obtain higher beam current, we made experiments using the LIS with a magnetic field by which a confinement effect can make higher beam current. We measured total current by Faraday cup and analyzed charge distribution by electrostatic ion analyzer. It is shown that the ion beam charge state is higher by a permanent magnet. |
20192458 | Diagnostic experiments at a 3 MeV test stand at Rutherford Appleton Laboratory (United Kingdom). | A front end is currently under construction consisting of a H(-) Penning ion source (65 keV, 60 mA), low energy beam transport (LEBT), and radio frequency quadrupole (3 MeV output energy) with a medium energy beam transport suitable for high power proton applications. Diagnostics can be divided either in destructive techniques such as beam profile monitor, pepperpot, slit-slit emittance scanner (preferably used missioning) or nondestructive, permanently installed devices such as photodetachment-based techniques. Another way to determine beam distributions is a scintillator with charge-coupled device camera. First experiments have been performed to control the beam injection into the LEBT. The influence of beam parameters such as particle energy and pensation on the two-dimensional distribution and profiles will be presented. |
20192457 | Gallium ion extraction from a plasma sputter-type ion source. | A broad mixed ion beam containing positive ions of gallium (Ga) was produced with a plasma sputter-type ion source. Liquid Ga was suspended on a tungsten reservoir to be sputtered and postionized in argon (Ar) plasma excited by a radio frequency (rf) power at 13.56 MHz. Optical emission spectra from the plasma near the Ga sputtering target had indicated that the release of Ga into plasma increased with increasing negative bias to the sputtering target. The ratio of Ga(+) current to Ar(+) current was measured to be about 1% with a quadrupole mass analyzer at 100 V extraction voltage for incident rf power as low as 30 W. Ions in the plasma were extracted through a pair of multiaperture electrodes. The homogeneity of Ga flux was examined by making a Ga deposition pattern on a glass substrate located behind the extractor electrodes. |
20192459 | Portable emittance measurement device. | In Institute for Theoretical and Experimental Physics (ITEP) the portable emittance measurements device is developed. It provides emittance measurements both with "pepper-pot" and "two slits" methods. Depending on the method of measurements, either slits or pepper-pot mask with scintillator are mounted on the two activators and are installed in two standard Balzer's cross chamber with CF-100 flanges. To match the angle resolution for measured beam, the length of the stainless steel pipe between two crosses changes is adjusted. The description of the device and results of emittance measurements at the ITEP ion source test bench are presented. |
20192460 | Emittance estimation by an ion optical element with variable focusing strength and a viewing target. | The emittance of an extracted ion beam can be estimated to first order by a series of three linear independent profile measurements. This estimation is restricted to the evaluation of an upper limit of the emittance value for a homogeneous, nonfilamented beam. The beam is assumed to be round, respectively elliptical, without any structure of the intensity distribution, no space charge has been assumed for the drifting beam, and the optics is assumed to be linear. Instead of using three different drift sections, a linear focusing element with three different focusing strengths can be used. Plotting the beam radius as function of focusing strength, three independent solutions can be used to calculate the Twiss parameters alpha, beta, and gamma and furthermore the emittance epsilon. Here we describe the measurements which have been performed with the SECRAL ion source at Institute of Modern Physics Lanzhou. |
20192461 | Emittance studies of the Spallation Neutron Source external-antenna H- ion source. | A new Allison-type emittance scanner has been built to characterize the ion sources and low energy beam transport systems at Spallation Neutron Source. In this work, the emittance characteristics of the H(-) beam produced with the external-antenna rf-driven ion source and transported through the two-lens electrostatic low energy beam transport are studied. The beam emittance dependence on beam intensity, extraction parameters, and the evolution of the emittance and twiss parameters over beam pulse duration are presented. |
20192462 | Control system for the Spallation Neutron Source H- source test facility Allison scanner. | Spallation Neutron Source is currently in progress of a multiyear plan to ramp ion beam power to the initial design power of 1.4 MW. Key to reaching this goal is understanding and improving the operation of the H(-) ion source. An Allison scanner was installed on the ion source in the test facility to support this improvement. This paper will discuss the hardware and the software control system of the installed Allison scanner. The hardware for the system consists of several parts. The heart of the system is the scanner plete with associated bias plates, slits, and signal detector. There are two analog controlled high voltage power supplies to bias the plates in the head, and a motor with associated controller to position the head in the beam. A multifunction data acquisition card reads the signals from the signal detector, as well as supplies the analog voltage control for the power supplies. To synchronize data acquisition with the source, the same timing signal that is used to trigger the source itself is used to trigger data acquisition. Finally, there is an industrial puter to control the rest of the hardware. Control software was developed using National Instruments LABVIEW, and consists of two parts: a data acquisition program to control the hardware and a stand alone application for offline user data analysis. |
20192463 | Drift distance survey in direct plasma injection scheme for high current beam production. | In a laser ion source, plasma drift distance is one of the most important design parameters. Ion current density and beam pulse width are defined by plasma drift distance between a laser target and beam extraction position. In direct plasma injection scheme, which uses a laser ion source and a radio frequency quadrupole linac, we can apply relatively higher electric field at beam extraction due to the unique shape of a positively biased electrode. However, when we aim at very high current acceleration such as several tens of milliamperes, we observed mismatched beam extraction conditions. We tested three different ion current at ion extraction region by changing plasma drift distance to study better extraction condition. In this experiment, C(6+) beam was accelerated. We confirmed that matching condition can be improved by controlling plasma drift distance. |
20192464 | Time structure of an accelerated beam using a radio-frequency quadrupole linac with direct plasma injection scheme. | In direct plasma injection scheme, the relation between the ion current from a laser ion source and the accelerated beam current by a radio-frequency quadrupole (RFQ) linac was studied by a series of the following analyses. First, ion current at beam extraction was calculated from measured plasma parameters using a scaling law. Second, the beam emittance at the entrance of acceleration electrode region was evaluated by the simulation of the ion extraction out of the ion source plasma using the result of the first calculation. Last, the accelerated beam current could be reproduced by the simulation of beam acceleration using the results of the second. The second calculation revealed the time variation in the injected beam parameter to the RFQ linac. Then it was proved that the time structure of the accelerated beam was different from that of the injection beam because the degree of the matching between the injected beam emittance and the RFQ acceptance varied with time. |
20192465 | Model for the description of ion beam extraction from electron cyclotron resonance ion sources. | The finite difference method trajectory code KOBRA3-INP has been developed now for 25 years to perform the simulation of ion beam extraction in three dimensions. Meanwhile, the code has been validated for different applications: high current ion beam extraction from plasma sources for ion implantation technology, neutral gas heating in fusion devices, or ion thrusters for space propulsion. One major issue of the development of this code was to improve the flexibility of the applied model for the simulation of different types of particle sources. Fixed emitter sources might be simulated with that code as well as laser ion sources, Penning ion sources, electron cyclotron resonance ion sources (ECRISs), or H(-) sources, which require the simulation of negative ions, negative electrons, and positive charges simultaneously. The model which has been developed for ECRIS has now been used to explore the conditions for the ion beam extraction from a still nonexisting ion source, a so called ARC-ECRIS [P. Suominen and F. Wenander, Rev. Sci. Instrum. 79, 02A305 (2008)]. It has to be shown whether the plasma generator has similar properties like regular ECRIS. However, the emittance of the extracted beam seems to be much pared to an ECRIS equipped with a hexapole. |
20192466 | Particle simulation for direct plasma injection in a radio frequency quadrupole matching section. | We have been investigating direct plasma injection scheme (DPIS) for high-intensity heavy-ion beam acceleration. In the DPIS, laser-produced plasma is directly injected into a radio frequency quadrupole (RFQ) linac. To study the beam dynamics of the ion injection in the DPIS, we tracked particle motions in the RFQ matching section using three-dimensional particle-in-cell method. As a result of the numerical simulation, we found that the electrostatic field generated by the extraction electrode reduces the transmission efficiency. To avoid the radially defocusing force, the input beam into the RFQ has to be initially convergent. In the DPIS, further optimization of the plasma density is required for better matching. |
20192467 | Carborane beam from ITEP Bernas ion source for semiconductor implanters. | A joint research and development of steady state intense boron ion sources for hundreds of electron-volt ion implanters has been in progress for the past 5 years. The difficulties of extraction and transportation of low energy boron beams can be solved by implanting clusters of boron atoms. In Institute for Theoretical and Experimental Physics (ITEP) the Bernas ion source successfully generated the beam of decaborane ions. The carborane (C(2)B(10)H(12)) ion beam is more attractive material due to its better thermal stability. The results of carborane ion beam generation are presented. The result of the beam implantation into the silicon wafer is presented as well. |
20192468 | Characteristics of liquid cluster ion beam for surface treatment. | A liquid cluster ion source, which is an ion source for the cluster beams produced with liquid materials, has been developed for the surface treatment of solid materials. The electrodes were designed for increasing the cluster beam intensity by puter simulation of beam trajectories. The peaks of the cluster size distributions of the water and ethanol cluster ion beams of 3 atm vapor pressure were approximately at 2.4x10(3) and 1.6x10(3) molecules, respectively. The cluster size distributions of ethanol clusters were not sensitive to the variations of the acceleration voltages (V(e)) and currents (I(e)) of the electrons for ionization when the V(e) and I(e) were larger than approximately 200 V and 200 mA, respectively. |
20192469 | Two-stage plasma gun based on a gas discharge with a self-heating hollow emitter. | The paper presents the results of tests of a pact two-stage bulk gas plasma gun. The plasma gun is based on a nonself-sustained gas discharge with an electron emitter based on a discharge with a self-heating hollow cathode. The operating characteristics of the plasma gun are investigated. The discharge system makes it possible to produce uniform and stable gas plasma in the dc mode with a plasma density up to 3x10(9) cm(-3) at an operating gas pressure in the vacuum chamber of less than 2x10(-2) Pa. The device features high power efficiency, design simplicity, pactness. |
20192470 | A tandem-based compact dual-energy gamma generator. | A dual-energy tandem-type gamma generator has been developed at E. O. Lawrence Berkeley National Laboratory and Sandia National Laboratories. The tandem accelerator geometry allows higher energy nuclear reactions to be reached, thereby allowing more flexible generation of MeV-energy gammas for active interrogation applications. Both positively charged ions and atoms of hydrogen are created from negative ions via a gas stripper. In this paper, we show first results of the working tandem-based gamma generator and that a gas stripper can be utilized in pact source design. Preliminary results of monoenergetic gamma production are shown. |
20192471 | ITEP MEVVA ion beam for rhenium silicide production. | The rhenium silicides are very attractive materials for semiconductor industry. In the Institute for Theoretical and Experimental Physics (ITEP) at the ion source test bench the research program of rhenium silicide production by ion beam implantation are going on. The investigation of silicon wafer after implantation of rhenium ion beam with different energy and with different total dose were carried out by secondary ions mass spectrometry, energy-dispersive x-ray microanalysis, and x-ray diffraction analysis. The first promising results of rhenium silicide film production by high intensity ion beam implantation are presented. |
20192472 | ITEP MEVVA ion beam for reactor material investigation. | Since 2008 the ion beam irradiation modeling experiments for the testing of reactor materials radiation hardness are under development at the ITEP heavy ion RFQ injector with MEVVA ion source. Ion beam irradiation method has certain advantages for such tests. One of them is high speed of defect formation. Moreover, the irradiated samples can be investigated by traditional investigation methodic because they have not radioactivity induced. The special sample support with electrostatic deflector was constructed and installed at the injector output. The result of ion beam dynamics simulation throughout the deflector as well as the detailed description of the test facility is presented. The first experimental results are presented as well. They have been demonstrated promising results. |
20192473 | Current capabilities and future needs for semiconductor ion implantation (invited). | For many years the mercial application for particle accelerators has been semiconductor ion implantation. These tools differ from other accelerators in many respects. In particular they are automated to a very high degree and, in addition to technical performance requirements their success depends on other key metrics including productivity, availability and cost of ownership. These tools also operate with a large variety of species, four orders of magnitude of energy range and five orders of magnitude of dose range. The ion source is a ponent of implanters with its own performance metrics that include beam current, lifetime, and materials cost. In this paper, we describe the primary applications for ion implantation and some of the beam line architectures that are used. We describe the ion source that has evolved for this application. Some key future challenges for implanter ion source development are also discussed. |
20192474 | Sealed operation of a rf driven ion source for a compact neutron generator to be used for associated particle imaging. | We present the recent development of a pact neutron generator to be used in conjunction with the method of associated particle imaging for the purpose of active neutron interrogation. In this paper, the performance and device specifications of pact generators that employ rf driven ion sources will be discussed. Initial measurements of the generator performance include a beam spot size of 1 mm in diameter and a neutron yield of 2x10(5) n/s with air cooling. |
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