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Feb 2002

Volume 73, Issue 2, pp. 241-1098

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Production of multiply charged Si and Fe ions from solid materials by sputtering and evaporating methods in a 2.45 GHz ECR source

Saori Sugiyama, Yushi Kato, and Shigeyuki Ishii

Rev. Sci. Instrum. 73, 542 (2002); http://dx.doi.org/10.1063/1.1430862 (3 pages) | Cited 4 times

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Multicharged Si and Fe ions are produced from solid materials in a 2.45 GHz electron cyclotron resonance (ECR) ion source. The ECR plasma is confined in a magnetic mirror field superimposed on an octupole magnetic field. Ar gas is normally chosen for working gas at pressures of 10−4 to 10−3 Pa. Si and Fe ions are produced by sputtering and evaporating solid materials, which are safe and easy to handle. The Fe (or Si) target is mounted at the tip of an insulated holder and inserted into the plasma. The negative dc bias voltages are applied to the target and multicharged Fe (or Si) ions are produced. Fe filament is evaporated in the ECR plasma by direct ohmic heating, and multicharged Fe ions are produced. Multicharged ions up to Fe6+ are produced by using both methods of sputtering and evaporating and Si4+ by using the sputtering method. The maximum ratio of the Fe and Si ion currents to total Ar ion current are about 15% and 13% obtained by the sputtering method, respectively. The maximum current densities of Fe+ and Fe4+ are 1.1×10−1 and 4.1×10−4 mA/cm2 obtained by the sputtering method, respectively. © 2002 American Institute of Physics.
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29.25.Ni Ion sources: positive and negative
07.77.Ka Charged-particle beam sources and detectors
52.50.Qt Plasma heating by radio-frequency fields; ICR, ICP, helicons
28.52.Av Theory, design, and computerized simulation
52.55.-s Magnetic confinement and equilibrium
68.49.Sf Ion scattering from surfaces (charge transfer, sputtering, SIMS)
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Metallic ion beam production at HIMAC

M. Sasaki, A. Kitagawa, M. Muramatsu, K. Jincho, N. Sasaki, T. Sakuma, W. Takasugi, and M. Yamamoto

Rev. Sci. Instrum. 73, 545 (2002); http://dx.doi.org/10.1063/1.1425779 (3 pages) | Cited 1 time

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In order to realize new investigations on physics, biology, and other fields, a metallic ion beam is quite effective and essential. To produce the metallic ion beam in an electron cyclotron resonance (ECR) ion source, how to supply the metallic gas into the ECR plasma is most important. At present, the NIRS-HEC, which is an 18 GHz ECR ion source installed for the Heavy Ion Medical Accelerator in Chiba at the National Institute of Radiological Sciences (NIRS), enables us to produce a stable Fe9+ beam of 180 eμA by the metal ions from volatile compounds technique. In addition, the development of a new gas supply method, using the electron-bombardment technique, is in progress. In this method, the tip of a metal target rod (2–6 mm diameter) at a high positive potential is melted by bombarding the thermoelectrons emitted from a surrounding hot filament and the evaporated gas is supplied into the ECR plasma. © 2002 American Institute of Physics.
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07.77.Ka Charged-particle beam sources and detectors
29.25.Ni Ion sources: positive and negative
52.50.Sw Plasma heating by microwaves; ECR, LH, collisional heating

Techniques for the measurement of ionization times in ECR ion sources using a fast sputter sample and fast gas valve

R. C. Vondrasek, R. H. Scott, R. C. Pardo, and D. Edgell

Rev. Sci. Instrum. 73, 548 (2002); http://dx.doi.org/10.1063/1.1430273 (4 pages) | Cited 2 times

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Two techniques for the discrete injection of material into an Electron Cyclotron Resonance ion source (ECRIS) have been developed for the purpose of measuring the ionization and confinement times of ion species. Previously only solid materials in conjunction with a pulsed laser were used in these studies due to the discrete material introduction produced by this configuration. The first method replaces the pulsed laser with a fast high voltage pulse applied to a sputter sample. The high voltage pulse has a rise time of 100 ns, fall time of 80.0 μs, and variable pulse duration. The second method utilizes a fast-pulsed gas valve capable of producing a gas pulse 160 μs in width. These pulse widths are well below the ionization times of the lower charge states and thus allows for time measurements to be made of all charge states. Both of these techniques can be employed to study the effects of rf power, coil configuration, biased disk, and gas mixing on ionization and confinement times. Rise times for neon, argon, and gold will be presented. © 2002 American Institute of Physics.
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29.25.Ni Ion sources: positive and negative

Radio-frequency ovens for ECR ion sources

M. Cavenago, T. Kulevoy, and S. Petrenko

Rev. Sci. Instrum. 73, 552 (2002); http://dx.doi.org/10.1063/1.1429306 (3 pages) | Cited 3 times

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Radio-frequency (rf) ovens have perspective advantages over their Ohmic equivalent in terms of uniformity of heating, separation (extending lifetime and use of reactive sample) and insulation; on the other side, rf losses in the coil must be minimized. Several geometries, crucibles, and coils were tested to optimize efficiency (power in the sample/total power); the final axial geometry with a copper coil is described, discussing the optimization of thermal contacts. A script to simulate the two-dimensional geometry of a rf oven (in particular, the wire separation and shape) was written; optimal working frequencies were found to be about or over 1 MHz, as confirmed by experiments, while the coil should be slightly longer than the sample. A temperature of 1680 K was reached with an iron crucible and 80 W of total rf power; silver and copper evaporations were tested; and carbon crucibles can reach higher temperatures (1750 K in a preliminary version). © 2002 American Institute of Physics.
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29.25.Ni Ion sources: positive and negative
07.20.Hy Furnaces; heaters

Thermal equilibrium among ion species into ECR plasma

M. Cavenago

Rev. Sci. Instrum. 73, 555 (2002); http://dx.doi.org/10.1063/1.1430031 (3 pages) | Cited 1 time

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The ion cooling exerted by lighter ions inside an ECR plasma is often credited as an explanation of the well-known gas mixing effect, since the ion temperature is about a constant Tp for all the ion species in the plasma. Here the energy balance equations are written in detail for any ion species, including the improved evaporation cooling in the collisional confinement regime. A formula for Tp and decoupled equations for small corrections around Tp are given, accounting for the colder gas input. The charge state distribution are written in closed form. Gas flow between plasma center and periphery is described. Some equilibria for most common gas mixing cases are compared, showing in particular the efficacy of neon. © 2002 American Institute of Physics.
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52.50.Sw Plasma heating by microwaves; ECR, LH, collisional heating
29.25.Ni Ion sources: positive and negative

High intensity metallic ion beams from an ECR ion source at GANIL

P. Lehérissier, C. Barué, C. Canet, M. Dupuis, J. L. Flambard, G. Gaubert, S. Gibouin, Y. Huguet, P. A. Jaffres, P. Jardin, N. Lecesne, F. Lemagnen, R. Leroy, J. Y. Pacquet, F. Pellemoine-Landré, et al.

Rev. Sci. Instrum. 73, 558 (2002); http://dx.doi.org/10.1063/1.1429316 (3 pages) | Cited 4 times

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In recent years, progress concerning the production of high intensity of metallic ion beams (58Ni, 48Ca, 76Ge) at GANIL have been performed. The metallic ion from volatile compound method has been successfully used to produce a high intensity nickel beam with the ECR4 ion source: 20 e μA of 58Ni11+ at 24 kV extraction voltage. This beam has been maintained for 8 days and accelerated up to 74.5 MeV/u by our cyclotrons with a mean intensity of 0.13 pμA on target. This high intensity, required for experiment, led to the discovery of the doubly magic 48Ni isotope. The oven method has been first tested with natural metallic calcium on the ECR4 ion source, then used to produce a high power beam (740 W on target, i.e., 0.13 pμA accelerated up to 60 meV/u) of 48Ca still keeping a low consumption (0.09 mg/h). A germanium beam is now under development, using the oven method with germanium oxide. The ionization efficiencies have been measured and compared. © 2002 American Institute of Physics.
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29.25.Ni Ion sources: positive and negative
07.77.Ka Charged-particle beam sources and detectors

LIMBE: A new facility for low energy beams

L. Maunoury, R. Leroy, T. Been, G. Gaubert, L. Guillaume, D. Leclerc, A. Lepoutre, V. Mouton, J. Y. Pacquet, J. M. Ramillon, R. Vicquelin, and The GANIL Ion Production Group

Rev. Sci. Instrum. 73, 561 (2002); http://dx.doi.org/10.1063/1.1430032 (3 pages) | Cited 9 times

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The goal of this article is to present the new facility LIMBE built at GANIL. This facility is dedicated to the ion–surface, ion–atom, and ion–molecule research. It is made of an ECR ion source called SUPERSHYPIE and two beam lines. We will describe the ECRIS, the beam properties, and the performances of LIMBE facility. © 2002 American Institute of Physics.
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29.25.Ni Ion sources: positive and negative
07.77.Ka Charged-particle beam sources and detectors

Studies on ECR4 for the CERN ion program

C. E. Hill, D. Küchler, R. Scrivens, and F. Wenander

Rev. Sci. Instrum. 73, 564 (2002); http://dx.doi.org/10.1063/1.1430033 (3 pages) | Cited 4 times

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The CERN heavy ion community, and some other high energy physics experiments, are starting to demand other ions, both heavy and light, in addition to the traditional lead ions. Studies of the behavior of the afterglow for different operation modes of the ECR4 at CERN have been continued to try to understand the differences between pulsed afterglow and continuous operation, and their effect on ion yield and beam reproducibility. The progress in adapting the source and ion beam characteristics to meet the new demands will be presented, as will new information on voltage holding problems in the extraction. © 2002 American Institute of Physics.
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29.25.Ni Ion sources: positive and negative
52.59.-f Intense particle beams and radiation sources
29.20.dk Synchrotrons

RECRIS-Romanian ECR ion source: Performances and experimental developments

S. Dobrescu and L. Schachter

Rev. Sci. Instrum. 73, 567 (2002); http://dx.doi.org/10.1063/1.1425780 (3 pages)

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The 14 GHz electron cyclotron resonance (ECR) ion source—RECRIS, developed at the National Institute for Physics and Nuclear Engineering (IFIN-HH) in Bucharest, Romania is presented. The source is conceived as a facility for atomic physics and material studies. The main constructive characteristics and performances of RECRIS are presented. The construction has some original characteristics: modular construction allowing simple dismounting and modification of the inner parts, high extraction voltage, up to 50 kV, and the possibility to use some techniques to enhance the performances, such as a biased disk, mixing gas, and others. The source is provided with a 90° analyzing magnet and with experimental devices and are presented as well. The main experimental device connected to the ECR ion source is a highly sensitive and wide mass range time-of-flight mass spectrometer for recoil ions. © 2002 American Institute of Physics.
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07.77.Ka Charged-particle beam sources and detectors
52.50.Sw Plasma heating by microwaves; ECR, LH, collisional heating
07.75.+h Mass spectrometers
29.25.Ni Ion sources: positive and negative

Enhanced highly charged ion production using a metal-dielectric liner in the KVI 14 GHz ECR ion source

L. Schachter, S. Dobrescu, G. Rodrigues, and A. G. Drentje

Rev. Sci. Instrum. 73, 570 (2002); http://dx.doi.org/10.1063/1.1430274 (3 pages) | Cited 9 times

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Forming on an aluminum surface a dielectric layer of alumina (aluminum oxide) in order to create a metal-dielectric (MD) structure increases the secondary-electron emission properties. The idea of using this material as a MD (Al–Al2O3) cylindrical liner inside an ECR ion source was previously tested in the 14 GHz ECRIS of IKF (Frankfurt/Main, Germany). The purpose of the present experiment was to observe the effect of such a MD liner on the high charge state operation of the KVI 14 GHz ECRIS, in particular in comparison to the technique of gas mixing. Measurements were made both with and without the MD liner, with pure argon and with an argon plus oxygen mixture. In the case of pure argon, the source with the MD liner is running remarkably stable. The high charge state ion beam currents are by far higher than those obtained in the situation where the source was operated with pure argon but without the MD liner. With MD liner, some low intensity oxygen peaks were clearly present in the spectra, implying that oxygen escaping or sputtered from the MD structure could give rise to an effect of “gas mixing.” Therefore, the effect of mixing small amounts of oxygen into an argon plasma without the liner was studied in the same conditions of rf power and O3+ peak intensity. The conclusion was that the high charge state beam increase is not due to the oxygen gas mixing effect. The reason for the good performances of the source in the presence of the MD liner can be the increased density of cold electrons, but other effects could occur as well. This is subject of further studies. © 2002 American Institute of Physics.
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07.77.Ka Charged-particle beam sources and detectors
73.40.Ns Metal-nonmetal contacts
79.20.Hx Electron impact: secondary emission
52.50.Sw Plasma heating by microwaves; ECR, LH, collisional heating

Development of an ECR ion source for carbon therapy

M. Muramatsu, A. Kitagawa, Y. Sato, S. Yamada, T. Hattori, M. Hanagasaki, T. Fukushima, and H. Ogawa

Rev. Sci. Instrum. 73, 573 (2002); http://dx.doi.org/10.1063/1.1429307 (3 pages) | Cited 8 times

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A compact electron cyclotron resonance ion source has been developed for heavy-ion medical facilities. The beam intensity and stability were considerably improved by recent modifications on three points (length of sextupole, cooling system for the extraction electrode, and position of the Einzel lens). Initial results of C4+ beam tests show that an intensity of 180 eμA can be routinely obtained with simple tuning. The best record was 220 eμA for C4+, which meets the medical requirements. Throughout these tests, CH4 gas was used with 0.1 cc/min and the extraction voltage was fixed at 25 kV. Results on beam emittance and long-term stability are also briefly discussed. © 2002 American Institute of Physics.
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29.25.Ni Ion sources: positive and negative
87.56.B- Radiation sources

Completion of the ATLAS ECR-I ion source upgrade project

D. P. Moehs, R. Vondrasek, R. H. Scott, R. C. Pardo, and J. M. Montgomery

Rev. Sci. Instrum. 73, 576 (2002); http://dx.doi.org/10.1063/1.1430510 (4 pages) | Cited 4 times

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A new 10 GHz electron cyclotron resonance ion source (ECRIS) has been constructed and commissioned for the ATLAS accelerator. This new source replaces the original ATLAS ECRIS that has been in operations since 1987. The goal of this upgrade project was to significantly improve the source performance while maintaining maximum operational flexibility for solid material feeds. The new source design includes a large magnetic-field gradient, aluminum plasma chamber, and bias disk following modern ECRIS design concepts. Eight solenoid coils from the original source along with a new iron yoke form the magnetic mirror. Hall Probe measurements showed the axial B field to be within 1% of the POISSON design model calculated at 400 A per coil. The injection and extraction mirror ratios are approximately 4.4 and 2.9, respectively, with a minimum field of 3.0 kG. A new aluminum plasma chamber houses the NdFeB hexapole magnets, which are encased in austenitic stainless steel to allow for direct water cooling. An open hexapole configuration provides six radial access ports, 1.7 cm×4.1 cm, to the plasma chamber for solid material feeds and vacuum pumping at an estimated rate of 20 l/s per radial port. Measurements of the hexapole field near the plasma chamber wall, 4 cm in radius, were within 13% of the designed B field of 9.3 and 5.7 kG along the poles and pole gaps, respectively. The first plasma in the new source was obtained on October 10, 2000. Already it has exceeded the best 16O6+ beam current obtained from the original ECR-I by a factor of roughly 2.3, achieving 140 e μA with a biased disk. The source is back in regular operation and ATLAS experiment runs have been performed with He, O, Ar, Kr, Ni, and Zr. © 2002 American Institute of Physics.
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07.77.Ka Charged-particle beam sources and detectors
29.25.Ni Ion sources: positive and negative

A new ECR ion source for atomic physics research at Institute of Modern Physics

Z. M. Zhang, H. W. Zhao, X. Z. Zhang, X. H. Guo, X. X. Li, L. T. Sun, Y. Cao, Y. C. Feng, J. Y. Li, H. L. Lei, H. Wang, J. Y. Gao, and B. H. Ma

Rev. Sci. Instrum. 73, 580 (2002); http://dx.doi.org/10.1063/1.1429317 (2 pages) | Cited 6 times

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A new electron cyclotron resonance (ECR) ion source (LECR3—Lanzhou Electron Cyclotron Resonance Ion Source No. 3) has been constructed this year. The main purpose of this source is to provide highly charged ion beams for atomic physics and surface physics research. The design of this ion source is based on the IMP 14.5 GHz ECR ion source (LECR2—Lanzhou Electron Cyclotron Resonance Ion Source No. 2) with double rf heating by inserting waveguide directly and aluminum chamber. Furthermore, the volume of the plasma chamber is larger than that of LECR2 so as to increase the rf power and improve beam intensity for highly charged ions. But the hexapole field on the chamber wall is kept the same value in order to compare with the performance of LECR2. After only four days conditioning the first test results were obtained. The final result of this ion source is expected to be better than LECR2’s. © 2002 American Institute of Physics.
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07.77.Ka Charged-particle beam sources and detectors
41.85.Ar Particle beam extraction, beam injection
41.75.-i Charged-particle beams

High-energy heavy ion cocktail beams at the 88 Inch Cyclotron (abstract)

M. A. McMahan, D. Argento, T. Gimpel, A. Guy, J. Morel, K. Osborne, C. R. Siero, R. K. Thatcher, D. Wutte, and C. Lyneis

Rev. Sci. Instrum. 73, 582 (2002); http://dx.doi.org/10.1063/1.1432454 (1 page)

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The combination of cyclotron and electron cyclotron resonance (ECR) ion source provides the ability to accelerate “cocktails” of ions, mixtures of ions of near-identical charge-to-mass ratio. This concept was developed soon after the first ECR ion source became operational at the 88 Inch Cyclotron and has become a powerful tool in the field of heavy ion radiation effects testing. The standard 4.5 MeV/nuc cocktail at a charge-to-mass ratio of 0.2 contains ions from B2+ to Bi41+. Copper and cobalt are provided by the direct insertion method, B is produced utilizing the MIVOC technique and Bi is produced with the oven technique. Recently, following upgrades to the AECR and the cyclotron vacuum system, a new high-energy heavy cocktail beam has been developed. This cocktail at a charge-to-mass ration of 0.27 using 400 MeV Ar11+ as a “pilot” beam, contains ions from B3+ to Xe38+ and provides accelerated ions with a range of 100 μm in Si, of great advantage for some of the newer-generation microelectronics. It has joined the 4.5 MeV/u heavy ion cocktail and the 32.5 MeV/u light ion cocktail as standards in the cyclotron’s cocktail repertoire. © 2002 American Institute of Physics.
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07.77.Ka Charged-particle beam sources and detectors

Design and construction of four-hole ECR ion source

H. Kashiwagi, T. Hattori, M. Okamura, Y. Takahashi, T. Hata, K. Yamamoto, S. Okada, and T. Sugita

Rev. Sci. Instrum. 73, 583 (2002); http://dx.doi.org/10.1063/1.1430034 (3 pages)

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When a large current is accelerated, many radio frequency quadrupole (RFQ) LINAC are needed, because the acceleration limit of a RFQ LINAC is 20 mA–30 mA. Therefore the same number of ion source are needed. But the limit is not the current limit of ion source. If the RFQ LINAC has many RFQ channels, it can accelerate large currents. We designed an accelerator with four RFQ channels to prove this principle. An ion source which extracts four equal beams from one chamber is needed for this RFQ LINAC. A four-hole ECR ion source was designed and manufactured after calculating the magnetic fields by OPERA, and simulating beam trajectory using the program FUGUN. In this ion source, since four extraction holes are located off axis by about 50 mm, the beam is deflected. We calculated this deviation. © 2002 American Institute of Physics.
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29.25.Ni Ion sources: positive and negative
29.20.-c Accelerators

A compact 2.45 GHz ECR ion source with permanent magnets for material science

E. Tojyo, I. Katayama, S. C. Jeong, M. Oyaizu, H. Ishiyama, H. Kawakami, K. Enomoto, and H. Miyatake

Rev. Sci. Instrum. 73, 586 (2002); http://dx.doi.org/10.1063/1.1429318 (3 pages) | Cited 1 time

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A compact 2.45 GHz electron cyclotron resonance (ECR) ion source has been developed as an etching device for diffusion experiments in the solid-state matter. This source is a little bit different from those of a usual industrial ECR device, i.e., it is to extract high intensity beams from a relatively small single hole with low emittance under the extraction voltage of several kV and high vacuum. Summary of the design, manufacture, and the initial beam extraction tests are described. © 2002 American Institute of Physics.
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07.77.Ka Charged-particle beam sources and detectors
41.85.Ar Particle beam extraction, beam injection
41.85.Lc Particle beam focusing and bending magnets, wiggler magnets, and quadrupoles
75.50.Ww Permanent magnets

Design of an all-permanent-magnet ECR ion source at the Cyclotron and Radioisotope Center

A. Yamazaki, M. Fujita, E. Tanaka, T. Shinozuka, T. Yokoi, T. Ozawa, and H. Tanaka

Rev. Sci. Instrum. 73, 589 (2002); http://dx.doi.org/10.1063/1.1429308 (3 pages) | Cited 1 time

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A new electron cyclotron resonance ion source has been designed and equipped with the new cyclotron at the Cyclotron and Radioisotope Center, Tohoku University. The ion source consists of a full permanent-magnet system with a microwave frequency of 14.5 GHz. The source has the following three main features: (1) V-style magnetization, (2) flat-bottomed magnetic-field distribution, and (3) field adjusting system. The measured magnetic-field strength in the plasma chamber is about 8% weaker than the calculated value. The extracted beam current is measured as the preliminary result. © 2002 American Institute of Physics.
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29.25.Ni Ion sources: positive and negative
29.20.dg Cyclotrons
07.55.Db Generation of magnetic fields; magnets

Effect of a biased electrode on operation of electron cyclotron resonance ion source using liquid He free superconduction solenoid coils

M. Imanaka, T. Kurita, M. Tsukada, I. Arai, S. M. Lee, and T. Nakagawa

Rev. Sci. Instrum. 73, 592 (2002); http://dx.doi.org/10.1063/1.1427026 (3 pages) | Cited 5 times

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We have constructed a liquid He free SC-ECRIS and successfully extracted intense beams of various heavy ions. To improve its performance, we installed a negatively biased electrode in the plasma chamber and observed its effect on the beam intensity systematically. We measured the beam intensity and the current of biased electrode as a function of both the applied bias voltage and the electrode position. Using the negatively biased electrode, the beam intensity of highly charged Xe ions was strongly enhanced. Furthermore, both the beam intensity and the current of biased electrode oscillated strongly. The frequency became higher when increasing the magnitude of bias voltage. This result shows that the biased electrode causes a certain instability in the electron cyclotron resonance plasma, so that the beam intensity is enhanced. In this contribution, we present the results of our experiment and the discussions about possible mechanisms of such instability. © 2002 American Institute of Physics.
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07.77.Ka Charged-particle beam sources and detectors
41.85.Ew Particle beam profile, beam intensity
29.25.Ni Ion sources: positive and negative
52.50.Sw Plasma heating by microwaves; ECR, LH, collisional heating
84.71.Ba Superconducting magnets; magnetic levitation devices

Computational design studies for an ion extraction system for a “volume-type” ECR ion source

H. Zaim and G. D. Alton

Rev. Sci. Instrum. 73, 595 (2002); http://dx.doi.org/10.1063/1.1430511 (3 pages) | Cited 1 time

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Numerical studies have been performed for optimally extracting high-intensity, space-charged-limited multicharged ion beams from an all-permanent-magnet, “volume-type” electron cyclotron resonance ion source, equipped with a three-electrode extraction system. These studies clearly demonstrate the importance of being able to adjust the extraction gap in order to ensure high quality, minimum divergence (highly transportable) ion beams. Optimum extraction conditions are reached whenever the plasma meniscus has an optimum curvature for a given current density. Optimum perveance (optimum current) values are found to closely agree with those derived from elementary analytical theory for extraction of space-charge-dominated beams. Details of the electrode system design as well as angular divergence and root-mean-square (rms) emittance versus extraction parameter data (e.g., perveance and extraction gap) are provided for ion beams of varying charge-state and mass, extracted under the influence of a mirror-geometry plasma confinement magnetic field. © 2002 American Institute of Physics.
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07.77.Ka Charged-particle beam sources and detectors
52.59.Sa Space-charge-dominated beams
28.52.Av Theory, design, and computerized simulation
52.55.-s Magnetic confinement and equilibrium

Effect of plasma electrode position on the beam intensity of heavy ions from a RIKEN 18 GHz electron cyclotron resonance ion source

Y. Higurashi, T. Nakagawa, M. Kidera, T. Aihara, M. Kase, and Y. Yano

Rev. Sci. Instrum. 73, 598 (2002); http://dx.doi.org/10.1063/1.1430512 (3 pages) | Cited 3 times

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To investigate the effect of the plasma electrode position on the beam intensity, we measured the beam intensity of Ar ions, with various charge states as a function of the electrode position. In this experiment, we observed that the beam intensity of highly charged Ar ions is strongly dependent on the electrode position and that there is the suitable position to maximize the beam intensity. The optimum position varies with the charge state of ions. The beam intensity of 1.3 mA for Ar8+ was obtained at the optimum plasma electrode position. © 2002 American Institute of Physics.
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07.77.Ka Charged-particle beam sources and detectors

Experimental study of ion extraction from a 2.45 GHz electron cyclotron resonance multicharged ion source

Yushi Kato, Saori Sugiyama, and Shigeyuki Ishii

Rev. Sci. Instrum. 73, 601 (2002); http://dx.doi.org/10.1063/1.1427027 (3 pages) | Cited 2 times

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Extraction and transport of multicharged ions have been experimentally investigated on a 2.45 GHz electron cyclotron resonance (ECR) source. The extractor consists of an electrode facing the ECR plasma (plasma electrode) and three cylindrical electrodes (E1–E3). The extractor is moved at several positions on the geometrical axis. The gap length between the plasma and E1 electrodes can be moved in vacuum while keeping gaps of the other electrodes constant. Characteristics of the total extraction current are investigated by a Faraday cup set just downstream at the extractor while simultaneously monitoring the currents flowing to electrodes and the drain in various experimental conditions. Several kinds of potential forms of the electrodes are investigated and the gap lengths are surveyed and optimized experimentally. The mass/charge spectrum of the extracted multicharged ion current is investigated by the Faraday cup set downstream at the sector magnet. The features of the extraction condition for the charge states are also investigated. After optimization in these procedures, the multicharged ion currents have been enhanced by 1 order of magnitude more than those in the previous experiments. © 2002 American Institute of Physics.
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07.77.Ka Charged-particle beam sources and detectors
52.50.Sw Plasma heating by microwaves; ECR, LH, collisional heating
41.85.Ar Particle beam extraction, beam injection
29.25.Ni Ion sources: positive and negative

Study of the extracted beam and the radial magnetic field of electron cyclotron resonance ion source at HIMAC

A. Kitagawa, M. Muramatsu, M. Sasaki, S. Yamada, S. Biri, K. Jincho, T. Okada, T. Sakuma, W. Takasugi, and M. Yamamoto

Rev. Sci. Instrum. 73, 604 (2002); http://dx.doi.org/10.1063/1.1427028 (3 pages) | Cited 4 times

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Experimental results on an 18 GHz electron cyclotron resonance (ECR) ion source (NIRS-HEC) and a 10 GHz ECR ion source (NIRS-ECR) at National Institute of Radiological Sciences (NIRS) show that an extracted beam intensity strongly depends on the radial magnetic field distribution generated by a permanent sextupole magnet. In order to understand these results, we simulated beam extraction under strong influences of space charge. In the simulation, a current intensity at a different position of an extraction slit is assumed to be roughly proportional to a corresponding transverse area of the ECR zone under the assumption that ions are extracted along a longitudinal magnetic flux line. The calculations show that an optimum value of the sextupole magnetic field strength may exist for a given extraction configuration and beam intensity. Based on the simulation, beam intensity measurements have been performed with six sextupole magnets having different magnetic field strengths for two ion sources, and the experimental results are consistent with the calculations. © 2002 American Institute of Physics.
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07.77.Ka Charged-particle beam sources and detectors
29.25.Ni Ion sources: positive and negative
41.85.Ar Particle beam extraction, beam injection
52.50.Sw Plasma heating by microwaves; ECR, LH, collisional heating
41.85.Ew Particle beam profile, beam intensity

Simulation of the extraction from an electron cyclotron resonance ion source under the influence of space charge

P. Spädtke

Rev. Sci. Instrum. 73, 607 (2002); http://dx.doi.org/10.1063/1.1430513 (4 pages) | Cited 2 times

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The typical extracted particle density from an ion source of the electron cyclotron resonance (ECR) type has been increased during the last few years by several improvements: stronger magnetic fields, higher radio frequency, biased probes, mixing gas, afterglow mode, and other means. The extraction system remained unchanged in most cases, causing problems in beam quality because of the stronger space charge. Simulation of the extraction is helpful in understanding the physics, but a correct simulation requires a three-dimensional model. Whereas the geometry and the solenoidal component of the magnetic field is cylinder symmetric, the hexapole field determines indirectly the spatial distribution of the ions by Coulomb interaction between electrons and ions. The area where ions are started for the simulation depends therefore on the hexapole field strength. If higher energy electrons within the plasma are present, they should be included to describe the actual plasma boundary more precise. The measured charge state distribution should be used to define the real composition of the plasma. Using all these ingredients, an accel-decel extraction system has been investigated which should be able to handle higher ion currents as were available from ECR sources so far. It could be shown that the emittance of the extracted beam strongly depends on a good matching of the particle density within the plasma to the extraction field strength. Any nonlinearity of the fields causes emittance growth. Such a nonlinearity is produced by an azimuthal change in the location of the plasma boundary. Therefore, it would be highly desirable to decrease the hexapole field close to the plasma side of the extraction system. A much better beam quality would be achievable. © 2002 American Institute of Physics.
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41.85.Ar Particle beam extraction, beam injection
07.77.Ka Charged-particle beam sources and detectors

Effect of plasma chamber surface for production of highly charged ions from ECRIS

M. Kidera, T. Nakagawa, Y. Higurashi, M. Kase, and Y. Yano

Rev. Sci. Instrum. 73, 611 (2002); http://dx.doi.org/10.1063/1.1427029 (3 pages) | Cited 2 times

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The effect of the surface of Al2O3 on the beam intensity of highly charged Ar ions is described. To investigate this effect clearly, we directly plated the surface with 20 μm Al2O3 of the Al cylinder (Al2O3 plating method). This cylinder was inserted into the plasma chamber and it covered its inner wall of. We then measured the beam intensity of highly charged Ar ions carefully. By comparing the beam intensity using the Al2O3 plating method and the Al cylinder, it is confirmed that the Al2O3 surface is very effective in increasing the beam intensity of highly charged heavy ions. The best result of 290 eμA of Ar11+ was obtained by using this method. © 2002 American Institute of Physics.
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07.77.Ka Charged-particle beam sources and detectors
52.50.Sw Plasma heating by microwaves; ECR, LH, collisional heating
29.25.Ni Ion sources: positive and negative

Topography of an electron cyclotron resonance plasma in the vacuum-ultraviolet spectral range

P. Grübling, J. Hollandt, and G. Ulm

Rev. Sci. Instrum. 73, 614 (2002); http://dx.doi.org/10.1063/1.1431699 (3 pages) | Cited 5 times

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The plasma topography of the vacuum-ultraviolet (VUV) radiation source ELISA (electron cyclotron resonance light source assembly) was investigated. ELISA is operated at a VUV spectrometer which allows two-dimensional images of the axially observable plasma shape to be taken with a spatial resolution of 150 μm in the spectral range from 40 to 400 nm. The VUV radiance profile of the electron cyclotron resonance plasma was investigated for different working conditions of the source, with the source operated with nitrogen and krypton. Under specific operating conditions, the observed plasma radiance profile shows a structure similar to calculations performed by the group of Andrä. It was shown for the first time that the plasma topography can be interpreted by an electron density distribution as simulated there for a monomode electron cyclotron resonance ion source. © 2002 American Institute of Physics.
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.25.-b Plasma properties
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