bluuebunny/crossref_metadata_2025 huggingface dataset:
Intense heavy ion beam production from IMP LECR3 and construction progress of a superconducting ECR ion source SECRAL
Authors: Zhao H. W. , Zhang Z. M. , He W. , Zhang X. Z. , Guo X. H. , Cao Y. , Yuan P. , Sun L. T. , Ma L. , Song M. T. , Zhan W. L. , Wei B. W. , Xie D. Z.
Published: May 2004

Intense heavy ion beams have been produced from IMP 14.5 GHz LECR3 by optimization of the ion source conditions and transmission efficiency. Highly charged stable beams, such as 325 eμA of Ar11+, 95 eμA of Xe26+, 7 eμA of Xe30+, 140 eμA of Fe13+, and 75 eμA of Ni12+, were obtained by 14.5 GHz rf power 800–1000 W. Furthermore, an advanced superconducting ECR ion source named SECRAL is being constructed. SECRAL is designed to operate at rf frequency 18–28 GHz with axial mirror magnetic fields 4.0 T at injection, 2.2 T at extraction, and sextupole field 2.0 T at the plasma chamber wall. The unique feature of this superconducting ECR source is that the sextupole is located outside of the three axial solenoid coils to reduce the interaction force and make the source more compact. Fabrications of the superconducting coils, cryostat, beam transmission line, and other components are almost completed. Tests of the superconducting magnet with sextupole and solenoid coils are under way.
Development of metallic ion beams at the Institute of Modern Physics
Authors: Cao Y. , Zhang Z. M. , Ma L. , Sun L. T. , Zhao H. W.
Published: May 2004

Many experiments have been made to produce metallic ion beams since 1998 at IMP (Institute of Modern Physics). We have designed a small oven that can reach a temperature of more than 1300 °C using 110 W electric power. Typical ion beam currents of 70 eμA of Ca12+, 60 eμA of Mg8+, 25 eμA of Pb27+ have been provided to the IMP cyclotron operation by the LECR2 (LanZhou ECR No. 2). We have also obtained some good results by the metallic ions from volatile compounds method on LECR3 (LanZhou ECR No. 3).
Emittance measurement at IMP LECR3
Authors: Cao Y. , Zhao H. W. , Ma L. , Zhang Z. M. , Sun L. T.
Published: May 2004

We have designed and built an emittance scanner which was installed at the beam line of IMP LECR3. The scanner measures the emittance of ECR ion source by the method of electric-sweep, typically named as Electric-Sweep Scanner (ESS). The horizontal and vertical emittances were both measured by two ESSs at the beam line of IMP LECR3. Some preliminary results were obtained. The detailed results and discussions will be presented.
Mevva ion source operated in purely gaseous mode
Authors: Yushkov George Yu. , MacGill Robert A. , Brown Ian G.
Published: May 2004

We have operated a vacuum arc ion source in such a way as to form beams of purely gaseous ions. The vacuum arc configuration that is conventionally used to produce intense beams of metal ions was altered so as to form gaseous ion beams, with only minimal changes to the external circuitry and no changes internally to the ion source. In our experiments we formed beams from oxygen (O+ and O2+), nitrogen (N+ and N2+), argon (Ar+), and carbon dioxide (C+, CO2+, O+, and O2+) at extraction voltage of 2–50 kV. We used a pulsed mode of operation, with beam pulses ∼50 ms long and repetition rate 10 pulses per second, for a duty cycle of about 50%. Downstream ion beam current as measured by a 5 cm diameter Faraday cup was typically 0.5 mA pulse or about 250 μA time averaged. This time averaged beam current is very similar to that obtained for metal ions when the source is operated in the usual vacuum arc mode. Here we describe the modifications made to the source and the results of our investigations.
On the physics of metal–dielectric structures in ECR ion sources
Authors: Schachter L. , Dobrescu S. , Stiebing K. E. , Meyer J. D.
Published: May 2004

In previous research we have demonstrated that metal–dielectric (MD) structures have high capabilities to enhance the high-charge-state ion production in electron cyclotron resonance ion sources. In order to explain this effect, dedicated experiments have been performed, in which changes of main plasma parameters in the presence of a MD structure have been observed and an explanation for the mechanism of this “MD effect” was given. In this contribution we present a new experiment where we have concentrated on the question whether the effect of the high-charge-state enhancement by the MD structures is due to the presence of just a dielectric layer in the plasma chamber (e.g., working simply as a breaking of the nonambipolar wall currents) or whether details of the structure of the layer play an essential role. By comparing ion charge state distributions and bremsstrahlung spectra for two MD cylinders, of drastically different layer thicknesses, the importance of the MD effect, and hence, of the detailed structure of this type of layer for the production of very highly charged ions is demonstrated.
Laser ion source based on a 100 J/1 Hz CO2-laser system
Authors: Balabaev A. , Kondrashev S. , Konukov K. , Lozhkin A. , Sharkov B. , Shumshurov A. , Charushin A. , Makarov K. , Satov Yu. , Smakovskii Yu. , Camut O. , Chamings J. , Kugler H. , Scrivens R.
Published: May 2004

The laser system is a key element of the laser ion source (LIS), significantly influencing source stability and reliability. A 100 J/1 Hz master oscillator-power amplifier CO2-laser system has been designed, built, and tested for a Pb25+ LIS, with the aim of producing the ion beam parameters compatible with an injection chain for the large hadron collider. The results obtained during commissioning of the laser at ITEP and CERN are presented. LIS parameters based on 100 J/1 Hz CO2-laser system and the use of such a source for the ITEP–TWAC project are discussed.
Electronics for fast ion extraction from EBIS devices
Authors: Höltermann H. , Becker R. , Kleinod M. , Müller I.
Published: May 2004

Future synchrotrons for cancer therapy could profit from single turn injection in terms of size, costs, and ease of operation [O. Kester, R. Becker, and M. Kleinod, Rev. Sci. Instrum. 67 (1996)]. Short (∼1.5 μs) and intense (∼1.3 mA) pulses of highly charged light ions (C6+, N7+, O8+) are a requirement for these future therapy facilities which can be provided by an EBIS ion source. Such a medically dedicated EBIS has an electron beam of 400 mA at 5 keV and needs an electron current density of 100 A/cm2 for a repetition rate of 10 Hz. To obtain a 1.5 μs ion pulse it is necessary to switch the drift tube potentials up to 1.6 kV (for a ratio of beam to drift tube of 1/20) in some 100 ns. To avoid spreading out of the pulse due to the restoration of the full space charge depression at locations where ions have already been extracted, the potentials applied to the drift tubes are changed with time. They will be adjusted for each drift tube according to the transit time of the ion pulse. Furthermore, the drift tubes are fully interpenetrating each other with tapered fingers in order to locally distribute the action of the applied potentials. This provides a potential wall, which is following the extracted ion pulse and results in a compressed short ion pulse for single turn injection into a synchrotron.
Charge sensitive evaluated ion and electron energy distributions of a vacuum arc plasma
Authors: Galonska M. , Hollinger R. , Spädtke P.
Published: May 2004

A metal vapor vacuum arc type ion source has been developed for the high current injector at the GSI accelerator facility for the production of high charge state uranium beams. This ion source provides a high intensity ion beam with a fraction of fourfold charged uranium ions up to 67% for injection into the linear accelerator. As part of the ion source development the ion and electron energy distributions have been measured with an electrostatic cylinder spectrometer device which discriminates charged particles with different energy to charge ratios. This allows a charge sensitive evaluation of ion energy distribution. Energy distributions have been measured for various discharge parameters, i.e., arc current, magnetic flux density, and cathode materials. Some important plasma parameters can be derived from these measurements: charge resolved ion energy distributions, mean electron energy and temperature, and the anode drop which in all support the development of a model of a vacuum arc plasma consisting of high charge states.
Optimization of the charge state distribution of the ion beam extracted from an EBIT by dielectronic recombination
Authors: Crespo López-Urrutia J. R. , Braun J. , Brenner G. , Bruhns H. , Lapierre A. , González Martı́nez A. J. , Mironov V. , Soria Orts R. , Tawara H. , Trinczek M. , Ullrich J.
Published: May 2004

The dielectronic recombination resonance (DRR) processes for highly charged krypton ions have been investigated through simultaneously observing the x-ray emission and the ions extracted at the Heidelberg EBIT while slowly scanning the electron beam energy. It was found that at their DR resonance electron energies, the yield of the He-like krypton ions was substantially reduced, whereas that of the Li-like krypton ions was correspondingly increased. At slightly higher electron energies similar features were observed for the Li- and Be-like krypton ions. From the observed ratios of the Li-like/He-like krypton ion currents, we have deduced the dielectronic recombination (DR) strength for the He-like ions, which was found to be in reasonable agreement with theoretical calculations. We have also concluded from the present experiments that the DRR processes can be used to modify the ion charge state distributions and to concentrate the extracted ion currents into particular charge states. This is particularly important for future charge breading experiments with short-lived radioactive isotopes.
Diagnosis of plasmas in compact ECR ion source equipped with permanent magnet
Authors: Suzuki T. , Sawado Y. , Iida T. , Fujii Y.
Published: May 2004

A compact electron cyclotron resonance (ECR) ion source equipped with permanent Nd2Fe14B magnets for mass spectrometry is presented, and the plasma density and electron temperature of the generated plasma are characterized using a Langmuir probe. The compact ion source is only 22.5 mm in internal diameter (1 in. tube), and 56 mm in length, and operates at high microwave frequencies of 7–10 GHz. A permanent ring magnet is introduced to establish a dispersive magnetic field in the ECR zone, and the effect of the position of the magnet is investigated. The plasmas are generated at low pressures of 10–150 mPa, at which the electron temperature and plasma density vary in the range 1–9 eV and 1016–1017 m−3. From an investigation of the effects of input power, pressure, and magnet position, mode jumps of the plasma discharge are observed with increasing input power, and the magnet position is found to be crucial to the tuning of the ion source.
Advanced magnetic calculations for high magnetic field compact ion source
Authors: Thuillier T. , Curdy J.-C. , Lamy T. , Sole P. , Sortais P. , Vieux-Rochaz J.-L. , Voulot D.
Published: May 2004

The design of the advanced electronic cyclotronic resonance ion source (ECRIS) requires relatively high axial and radial magnetic inductions to allow the ECR frequency increase and to take advantage of the subsequent density increase (scaling laws). The last improvements of the commercial rare-earth magnet characteristics open new opportunities for ECRIS and enable the design of very high hexapolar magnetic fields for next generation compact ECRIS. Moreover, the high temperature superconducting (HTS) wires allow designing reliable and compact axial field coils (30 K cooled) at a very effective cost. It is thus very relevant to study a compact hybrid ECRIS using high remanence magnet and HTS technologies. In such a design, the volume of the plasma chamber is a free parameter that can be adjusted to the user requirement. It can be dedicated to very high ionic current production or high charge state production, pulsed, or cw operations. This paper presents the three-dimensional overall simulation of a 3 T axial magnetic field compact ECRIS with a high radial field sextupole composed with several magnet types and reaching ∼1.9 T in front of the radially magnetized magnets. This design study will lead to the building of the 28–40 GHz A-PHOENIX source at the laboratory which will deliver its first beam by the end of 2004.
Visible light spectrometry measurements for studying an ECRIS plasma and especially applied to the MONO1001 ion source
Authors: Tuske Olivier , Maunoury Laurent , Pacquet Jean-Yves , Barué Christophe , Dubois Mickael , Gaubert Gabriel , Jardin Pascal , Lecesne Nathalie , Leherissier Patrick , Lemagnen Frederic , Leroy Renan , Saint-Laurent Marie-Genevieve , Villari Antonio C. C.
Published: May 2004

The cylindrical geometry of the magnetic confinement of the MONO1001 electron cyclotron resonance (ECR) ion source made in GANIL [P. Jardin et al., Rev. Sci. Instrum. 73, 789 (2002)] allows us to measure radial characteristics of the working ECR plasma with helium gas. The physical and the geometrical characteristics of the resonance surface inside the working ECR source have been quantified with the help of a visible light spectrometer. Hence, we have deduced a shape of the electron cyclotron resonance ion sources resonance surface which corresponds closely to our magnetic calculations.
Paramagnetic NO2 centers in thin γ-irradiated HfO2 layers on (100)Si revealed by electron spin resonance
Authors: Stesmans A. , Afanas’ev V. V. , Chen F. , Campbell S. A.
Published: May 2004

Electron spin resonance (ESR) analysis reveals the incorporation of N in (100)Si/HfO2 structures with ultrathin amorphous HfO2 films deposited by chemical vapor deposition (CVD) using Hf(NO3)4 as precursor, through detection, after 60Co γ-irradiation, of NO2 radicals (density ≳55 at. ppm). The molecules are found to be stabilized and likely homogeneously distributed in the HfO2 network. Some network forming N entity is suggested as a precursor, transformed into ESR-active NO2 upon γ-irradiation. The interesting N incorporation aspect appears inherent to the particular CVD process.
Numerical modeling of excited hydrogen atoms and their transport in hydrogen negative ion sources
Authors: Takado N. , Miyamoto K. , Hatayama A.
Published: May 2004

Improvements are made of a Monte Carlo neutral transport code for the analysis of negative ion sources. These improvements make it possible to calculate the density of excited atoms, and to compare the numerical results with spectroscopic measurements, such as the Hα Balmer spectrum (n=3→n=2, n: principle number). The line-integrated intensities of the Hα spectrum in a tandem-type negative ion source are investigated. The excited hydrogen atoms in the n=3 level are populated by excitation, mutual neutralization (H−+H+→H(n)+H), and dissociation of H2, etc. The simulation results show that mutual neutralization greatly contributes to the intensity of the Hα spectrum, especially in the extraction region. In addition, near the filament in the driver region, the excitation process due to the fast electrons greatly contributes to the intensity of the Hα spectrum.
Numerical analysis of negative ion temperature in a negative ion source
Authors: Hatayama A. , Makino K. , Sakurabayasi T. , Miyamoto K. , Ogasawara M. , Bacal M.
Published: May 2004

To understand the origin of the two energy groups of volume produced H− ions observed in the multicusp, hybrid-type H− ion source (Camembert III), numerical analysis by the three-dimensional Monte Carlo simulation code has been done. Realistic multicusp geometry and the electric field near the filament are taken into account in the model. The energy relaxation process by Coulomb collision is also included in the model by the Monte Carlo method. Under the typical low-pressure condition of Camembert III, high-energy H− ions are clearly observed in the central region. The origin of these high-energy H− ions is possibly explained by the combined effects of (1) acceleration by electric field near the filament and (2) relatively large energy-loss time of these high-energy H− ions. However, the low energy group is not clearly observed in the simulation. The low energy H− ions with original energy (∼0.05 eV) have enough time to relax their energy towards the relatively high temperature of the background H+ ions, because their energy relaxation time is much smaller than the confinement time.
Self-consistent multicomponent plasma sheath theory for the extraction of H− ions (invited)
Authors: Becker Reinard
Published: May 2004

A self-consistent one-dimensional plasma sheath theory is presented to provide the basis for a correct numerical simulation of the extraction of volume produced H− ions. The plasma may consist not only of electrons and H− ions, but may also contain other positive ions such as protons, molecular ions and those of heavier elements, like cesium or tantalum. For the transition from the classical plasma sheath with a falling potential to the extraction region for H− ions with an increasing potential there exists the problem of a saddle point with adverse optical properties. This is eliminated by requiring sufficient space charge of H− ions near the extraction electrode. The formation of a virtual cathode in the extraction region by reflected positive ions is also taken into account. The integration of the Poisson equation in the extraction region establishes a criterion to avoid the creation of a nonphysical periodical sequence of potential maximums and minima. This criterion is an antithesis to the Bohm sheath criterion and has a corresponding interpretation: a virtual cathode in the extraction region can only be avoided, if the space charge of positive ions rapidly decreases. The acceptable range of parameters is thus reduced considerably. The resulting axial potential function is then used to derive the shape of the plasma wall electrode in the vicinity of the ion beam edge in order to obtain an aberration free beam boundary, this information being equivalent to the Pierce angle in the case of solid electron or ion emitters.
Study and preliminary results for a new type of ECR H− ions source
Authors: Benmeziane Karim , Ferdinand Robin , Gobin Raphael , Gousset Gerard
Published: May 2004

With the passing of the years, the need has been growing to be able to build a high current source with a long lifetime. An H− ion production code has been developed to improve the understanding on this ion production. At the same time very promising experimentation is going on at CEA-Saclay on an ECR H− ion source. This code is split in two parts. A PIC 1D MCC 3D code (particle in cell in 1D Monte Carlo with collision in 3D) is in charge of establishing the electron energy distribution function (EEDF), which is later used in a fluid code. This second code calculates the chemistry of the H− ion production. The 2D configuration of the study obliges us to choose a PIC code instead of a Boltzmann one. Two important difficulties are considered. The first one is due to a very low pressure (under 10 mTorr) as it is common in H− production experiments. The second difficulty is to accurately inject the high power discharge (few-tenths kW), usually demanded for such sources. This condition often carries divergences in the PIC code. This code is able to decrease the pressure down to 6 mTorr with a discharge of a few tenths of a kilowatt with a good reliability. This article describes the solution used in the code and the results useful in bringing the development of a new type of long lifetime H− ion source.
Control of negative ion beam uniformity by using multipower supplies for arc discharge
Authors: Ikeda K. , Takeiri Y. , Kaneko O. , Nagaoka K. , Oka Y. , Osakabe M. , Tsumori K. , Sato M. , Asano E. , Kawamoto T.
Published: May 2004

Multipower supplies for the arc discharge are installed to improve beam uniformity of a large size of the neutral beam injection system in the large helical device (LHD). The plasma tends to shift on the upper side of the arc chamber when the same arc voltage is applied to all filaments. The arc discharge current distribution becomes uniform as a consequence of the individual voltage control, but about 20 V difference of the arc voltage between the top and bottom circuits is required. We have estimated the beam profile from each acceleration grid by comparing the calculation and measurement of the beam profile of Hα and calorimeter. The uniformity of arc discharge has been improved in most regions without the discharge adjustment by a horizontal filament connection. The controllability of the arc discharge distribution of the horizontal filament connection is better than that of the vertical filament connection. The efficiency of the beam production is improved by about 10% in the case of the horizontal filament connection. As a result 3.7 MW of the beam injection has been achieved in the LHD 6th experimental campaign in 2003.
Numerical analysis of plasma spatial uniformity in negative ion sources by a fluid model
Authors: Mizuno T. , Kitade Y. , Hatayama A. , Sakurabayashi T. , Imai N. , Morishita T. , Inoue T.
Published: May 2004

A fluid plasma model of negative ion sources is developed to analyze a spatial nonuniformity of plasma profile in the extraction region. According to a preliminary two-dimensional (2D) analysis in the direction perpendicular to the magnetic-filter field, the E×B and diamagnetic drifts of electrons are shown to be almost cancelled. On the other hand, ion flow arises from the synergic effect of Lorentz force and the electric field force. This ion flow is one of the possible causes of the plasma nonuniformity in the extraction region.
Acceptance of the channel for modification of materials (L3A) of the Tesla accelerator installation
Authors: Beličev P. , Šiljegović M. , Dobrosavljević A. , Nešković N.
Published: May 2004

The channel for modification of materials (L3A) of the Tesla Accelerator Installation, in the Vinča Institute of Nuclear Sciences, connected to the mVINIS ion source, consists of an ion beam transport line and an interaction chamber enabling the ion beam assisted deposition. The 8.4 m long beam line, starting at an analyzing slit after an analyzing magnet, contains two electrostatic quadrupole triplet lenses: a 90° bending magnet and an electrostatic beam scanner. The maximal beam transmission coefficient, e.g., for 60 keV N4+ beam, has not exceeded 30%. At the time the beam line was designed, the mVINIS ion source was not commissioned, so that the emittances of the beams it delivered were underestimated. This is one of the reasons for the low transmission performance of the beam line. In this article the results of the beam line acceptance calculations are presented and compared with the measured beam emittances. The calculations are based on the transfer matrix formalism with no space charge taken into account. The suggestions for improving the beam transmission performance of the beam line are given.
ECRIS development for stable and radioactive pulsed beams
Authors: Sortais P. , Bouly J.-L. , Curdy J.-C. , Lamy T. , Sole P. , Thuillier T. , Vieux-Rochaz J.-L. , Voulot D.
Published: May 2004

The latest 28 and 37.5 GHz developments show that very intense pulsed beams of medium charge states can be produced with an ECRIS. We will present latest results obtained with PHOENIX 28 GHz in afterglow mode operation and specially the capacity of the source to produce high current of medium charge states despite a relatively low radial magnetic confinement system. Initially, these developments have been made for Pbn+ ion production for the LHC. A program is now underway by using a very strong ionic pumping effect in order to produce highly bunched beams of radioactive ions suitable for synchrotron acceleration for the CERN Beta-beam project. The purpose of this program consists of producing about 1012 of He6 or Ne18 ions/bunch within 100 μs pulse durations and with a 10 Hz repetition rate. This development must use two ECRIS advantages: the gas efficiency and the bunching capability. We will present a concept showing how we can bunch and ionize the radioactive gas injected in a cw operation source. Experimental data will be presented to illustrate this approach. To match the ionizing time to the time structure of the synchrotron used for the postacceleration we have to imagine a pulsed device using 60 GHz rf power and above; this is the purpose of this presentation.
Self-consistent, unbiased root-mean-square emittance analysis
Authors: Stockli Martin P. , Welton R. F. , Keller R.
Published: May 2004

We present a self-consistent method for analyzing measured emittance data that yields unbiased estimates for the root-mean-square (rms) emittance. The self-consistent, unbiased elliptical exclusion analysis uses an ellipse to determine the bias from the data outside the ellipse, before calculating the rms emittance from the bias-subtracted data within the ellipse. Increasing the ellipse size until the rms emittance estimate saturates allows for determining the minimum elliptical area that includes all real signals, even those buried in the noise. Variations of the ellipse shape and orientations are used to test the robustness of the results. Background fluctuations cause fluctuations in the rms emittance estimate, which are an estimate of the uncertainty incurred through the analysis.
The low-field permanent magnet electrostatic plasma lens
Authors: Goncharov A. , Gorshkov V. , Maslov V. , Zadorozhny V. , Brown I.
Published: May 2004

We describe the status of ongoing research and development of the electrostatic plasma lens as used for the manipulation of high current broad beams of heavy ions of moderate energy. In some collaborative work at Lawrence Berkeley National Laboratory the lens was used to good effect for carrying out high dose ion implantation processing. In the process of this work a very narrow range of low magnetic field was found for which the ion-optical characteristics of the lens improved markedly. Subsequent theoretical analysis and computer modeling has led to an understanding of this phenomenon. These serendipitous results open up some attractive possibilities for the development of a new compact and low cost plasma lens based on permanent magnets rather than on current-driven field coils surrounding the lens volume. The development of this kind of lens, including both very low noise and minimal spherical aberration effects, may lead to a tool suitable for use in the injection beam lines of high current heavy ion linear accelerators. Here we briefly review the lens fundamentals, some characteristics of focusing heavy ion beams at low magnetic fields, and summarize recent theoretical and experimental developments, with emphasis on the relevance and suitability of the lens for accelerator injection application.
Test results of 18 GHz ECR charge breeder for KEK–JAERI RNB facility
Authors: Jeong S. C. , Oyaizu M. , Tojyo E. , Kawakami H. , Ishiyama H. , Miyatake H. , Enomoto K. , Watanabe Y. , Katayama I. , Nomura T. , Matsuda M. , Osa A. , Ichikawa S.
Published: May 2004

Some of the test results of KEK ECR charge breeder made for KEK–JAERI RNB facility are presented and discussed. The charge breeding efficiencies for singly charged ions of noble gases have been measured; typically 13.5% of Ar9+, 10.4% of Kr12+, and 6.8% of Xe20+ with a global efficiency of about 50%. By injecting pulsed Xe1+ ion beam into the charge breeder, the time necessary for charge breeding has been also measured and found to be about 60 ms for Xe21+ ions. As an effort to reduce the residual gas ions incidentally existing in the plasma chamber of the charge breeder a nonevaporable getter has been tested, and the preliminary results are discussed.
Negative ions for heavy ion fusion and semiconductor manufacturing applications
Authors: Hahto S. K. , Hahto S. T. , Kwan J. W. , Leung K. N. , Grisham L. R. , Saadatmand K. , Benveniste V.
Published: May 2004

Radio frequency driven multicusp source was set up to run chlorine plasma and the source performance was compared between positive and negative chlorine ion production. A maximum Cl− current density of 45 mA/cm2 was achieved at 2.2 kW of rf power with electron to negative ion ratio of 7 and positive to negative ion ratio of 1.3. 99.8% of the total negative chlorine beam was atomic Cl−. To produce negative boron ions for semiconductor manufacturing applications, a noncesiated, sputtering-type surface production ion source was constructed. An external rf antenna geometry and large LaB6 converter were implemented in the source design. Maximum B2− ion current density of 1 mA/cm2 was achieved at 800 W of rf power and −600 V converter voltage. Total B2− ion current was 1.8 mA.
Contribution of wall material to the vibrational excitation and negative ion formation in hydrogen negative ion sources (invited)
Authors: Bacal M. , Ivanov A. A. , Glass-Maujean M. , Matsumoto Y. , Nishiura M. , Sasao M. , Wada M.
Published: May 2004

The wall production contribution to the negative hydrogen ion formation in multicusp ion sources has been investigated using the photodetachment diagnostic (for determining the negative ion density and temperature), negative ion and electron extraction, and vacuum ultraviolet (VUV) emission spectroscopy. The wall material was modified either by depositing thin films from filaments made of different material or by depositing fresh material of the same filament. Thus we show that a fresh tantalum film leads to enhanced negative ion density and enhanced temperature of the hot negative ion population. The slow poisoning effect due to argon additive also indicates the presence of the wall contribution to H− formation. The study of the VUV spectra with different wall materials indicates the presence of vibrationally excited states of H2.
New developments in rf- and filament-volume H− ion sources for accelerators (invited)
Authors: Peters J.
Published: May 2004

Since volume-produced negative ions were found in 1977 at the Ecole Polytechnique in France, H− volume sources have been developed in North America, Europe, and Asia. There are sources for continuous wave, high (5%) and low (0.01%) duty factors. Currents up to 120 mA have been reached. Several techniques have been applied. Plasma heating has been done with filaments and later also with radio frequency (rf) power. The rf frequency has been varied over a wide frequency range. Different types of rf coupling have been used. Also gas mixing, cesiation, and several extraction methods have been tested. The report gives a survey with emphasis on new developments.
Characterization of a compact filament-driven multicusp ion source for low energy time-of-flight Rutherford backscattering spectrometry application
Authors: Dangtip S. , Junphong P. , Ano V. , Lekprasert B. , Suwannakachorn D. , Thongnopparat N. , Vilaithong T.
Published: May 2004

Because of the limited pulse height energy resolution of a detector, conventional Rutherford backscattering spectrometry (RBS) requires an energy of the incident α particle to be in the MeV region. At Chiang Mai University we have researched the possibility of utilizing a 280 keV nanosecond pulse of helium ions for RBS applications. We have chosen a compact filament-driven multicusp ion source of 2.6 cm in diameter and 8 cm in length being investigated for the time-of-flight RBS applications. In this article, we present the general ion source performance using helium, nitrogen, and argon for generating the discharge plasma. The general ion source characteristics have been measured and analyzed. The measurements also include the extractable ion current and the ion beam emittance. We have performed beam extraction calculations with a computer simulation code KOBRA. Results of the measurements and calculations will be presented and discussed.
Production of multicharged iron ions by using pyrolytic boron nitride crucible and application to material processing
Authors: Kato Yushi , Tomida Masashi , Ishii Shigeyuki
Published: May 2004

Multiply charged ions of iron are produced from solid material in a 2.45 GHz electron cyclotron resonance (ECR) ion source by using a crucible made from pyrolytic boron–nitride (pBN) with several shields suppressing radiation. The evaporator is set on the geometrical axis. The multicharged ions are extracted from the opposite side of mirror end against the evaporator. Extraction voltage is normally 10 kV. The optimum conditions for production of multicharged iron ions are investigated experimentally. The ion beams can be provided to a newly constructed beam line for the ion irradiation of the substrate installed on the beam line. Multicharged iron ion beams have been utilized to form iron silicides and to enhance light catalytic performance of titanium–dioxide (TiO2) thin films. Formation of iron disilicide (β-FeSi2) has been identified, as well as enhancement of photocatalytic performance of the TiO2 thin films in the visible light region without degradation in the UV light region.
The status of the spallation neutron source ion source
Authors: Welton R. F. , Stockli M. P. , Murray S. N. , Keller R.
Published: May 2004

The ion source for the spallation neutron source (SNS) is a radio-frequency, multicusp source designed to deliver 45 mA of H− to the SNS accelerator with a pulse length of 1 ms and repetition rate of 60 Hz. A total of three ion sources have been fabricated and commissioned at Lawrence Berkeley National Laboratory and subsequently delivered to the SNS at the Oak Ridge National Laboratory. The ion sources are currently being rotated between operation on the SNS accelerator, where they are involved in ongoing efforts to commission the SNS LINAC, and the hot spare stand (HSS), where high-current tests are in progress. Commissioning work involves operating the source in a low duty-factor mode (pulse width ∼200 μs and repetition rate ∼5 Hz) for extended periods of time while the high-current tests involve source operation at full duty-factor of 6% (1 ms/60 Hz). This report discusses routine performance of the source employed in the commissioning role as well as the initial results of high-current tests performed on the HSS.
Static and dynamic characteristics of plasma lens with modified magnetic field geometry
Authors: Chekh Yu. , Goncharov A. , Protsenko I.
Published: May 2004

We describe some results of the investigation of static and dynamic characteristics of a plasma lens (PL) with a modified configuration of magnetic field lines. The axial and radial field gradients are minimized in the central region of the lens. This should promote the suppression of nonlinear vortex-like structures and the decrease of spherical aberrations. The characteristics of the focused broad heavy metal ion beams have been measured. The focusing properties of the lens significantly depend on the beam current, on the mode of power supplying to the PL electrodes and on the magnetic field strength. Studying the PL properties in a range of low magnetic fields has shown that the focusing possesses a nonstationary character and a regular decrease of the lens strength is observed. At the same time, the presence of regimes with the absence of focusing breakups and noise growth of the ion beam focused by the lens is determined.
Design and simulation of ion optics for ion sources for production of singly charged ions
Authors: Zelenak A. , Bogomolov S. L.
Published: May 2004

During the last 2 years different types of the singly charged ion sources were developed for FLNR (JINR) new projects such as Dubna radioactive ion beams, (Phase I and Phase II), the production of the tritium ion beam and the MASHA mass separator. The ion optics simulations for 2.45 GHz electron cyclotron resonance source, rf source, and the plasma ion source were performed. In this article the design and simulation results of the optics of new ion sources are presented. The results of simulation are compared with measurements obtained during the experiments.
High temperature electron beam ion source for on-line production of isotopes of refractory elements
Authors: Panteleev V. N. , Barzakh A. E. , Fedorov D. V. , Ivanov V. S. , Moroz F. V. , Orlov S. Yu. , Seliverstov M. D. , Volkov Yu. M. , Tecchio L. , Andrighetto A. , Stroe L.
Published: May 2004

A high temperature electron beam ion source (HTEBIS) for production of single charge ions of refractory elements was built and on-line used for production of isotopes of Fe, Co, Cu, Rh, and Pd. Off-line ionization efficiency measurement of pointed out elements have been carried out. The yields of some neutron rich isotopes of these elements, when HTEBIS was used with the uranium carbide target have been measured. The measured yields have been compared with calculated ones, obtained from experimentally defined cross-sections. A new designed and off-line tested version of HTEBIS with electron emitting cathode placed from the extraction electrode side has been discussed.
Very high-temperature ion source
Authors: Kousmine R. N. , Martynov M. I. , Prokhorov A. S. , Sokolov D. V.
Published: May 2004

This paper represents the next step in the development and research of high-temperature ion sources of refractory metals. The very high-temperature ion source is created on the basis of the already produced high-temperature source for palladium ions. The basic difficulties of such device designing, the successes, and perspective tasks are presented.
Mass separation of ion beams using transverse radio frequency electric field (abstract)
Authors: Wada M. , Asai N. , Kasuya T. , Maeno S.
Published: May 2004

A condition to achieve a mass separation of an ion beam at a given energy by means of applying a transverse radio frequency (rf) electric field was derived. Effectiveness of the scheme was examined with a He ion beam of energy below 2 kV. An array of four-stage electrodes produced distributed 13.56 MHz rf field to realize a function of a velocity filter. When the extraction voltage of the beam was adjusted to yield a velocity predicted from the theory, the beam current showed transmission as large as 80% through the array of electrodes.
Optimization method to reduce the nonlinear effects in space charged limited emission diode (abstract)
Authors: Lemaire J. L. , Guilhem D. , Lagniel J.-M. , Pichoff N.
Published: May 2004

We have studied the evolution of electron or ion beams in axially symmetric extraction systems dominated by space charge. At first, electric and magnetic field components induced by a high voltage diode and an external magnetic focusing are computed using analytical formulas. This new approach allows a better insight into the individual effects of the three nonlinear forces (electric, magnetic, and space charge) on the emittance evolution. Indeed, the optimization method acts on the root-mean-square emittance minimization. More complicated extraction geometries can be handled thanks to numerical simulation codes using this method.
High power beam injection using an improved negative ion source for the large helical device
Authors: Tsumori K. , Nagaoka K. , Osakabe M. , Takeiri Y. , Ikeda K. , Kaneko O. , Oka Y. , Kawamoto T. , Asano E. , Sato M. , Kondo T. , Asano S. , Suzuki Y. , Okuyama T. , Ichihashi K.
Published: May 2004

In this article we describe the first results of beam injection using an improved negative ion source, which consists of a set of steering and multislot grounded grids. The set of the grids is designed to achieve high power beam injection for the large helical device (LHD). The main purpose in replacing the conventional multiaperture with multislot grids is to reduce the heat load onto the grid. By adopting the multislot grid, the frequency of voltage breakdown at the acceleration gap decreased considerably and the maximum beam energy attained was 180 keV, which is one of the target values of the LHD neutral beam injector (NBI). The maximum injection power reached 4.4 MW, consequently. The heat load onto the multislot grid was water calorimetrically measured and the load is suppressed by 50% compared to the multiaperture case. In the condition for maximum injection power, the beam profile obtained in the accelerator with the multislot grounded grid becomes vertically elongated due to the asymmetric electric field close to the grid slot. Although some part of this elongated beam is lost at the injection port, the multislot grid has enough performance for beam injection.
Simple structure holey-plate ion source
Authors: Yoshida Yoshikazu , Ogura Hiroshi
Published: May 2004

A high-efficiency, lightweight, and low-cost microwave ion source, created and sustained by evanescent waves emitted from a parallel-plate type source with a holey-plate has been studied. This source is called a holey-plate (HP) ion source. The microwaves at 2.45 GHz propagate inside the parallel-plate structure and then are converted into an evanescent mode through the use of a HP with 3-mm-diam holes. The plate dimensions are 100 mm×140 mm and are separated by 10 mm. In these experiments, the entire unit of the parallel plate is placed in a vacuum chamber. Dense plasma is produced only on the HP. A 78 mm×108 mm argon ion beam is extracted from the HP using a single grid with 3-mm-diam holes. The ion current densities are in excess of 1.2 mA/cm2 at an extraction voltage of 500 V.
A continuous wave microwave proton source and low energy beam transport for the IUCF cyclotrons
Authors: Derenchuk Vladimir P.
Published: May 2004

A high reliability and low maintenance proton injector for a 20–750 keV cw radio frequency quadrupole (RFQ) has been constructed and installed to supply beam for acceleration to 208 MeV by the Indiana University Cyclotron Facility cyclotrons. The injector includes a 6 mA 2.45 GHz microwave proton source, two solenoids to match the 20 keV beam to the RFQ, a third pulsed solenoid for modulating the beam intensity out of the RFQ and an electrostatic chopper that operates at 17.79 MHz to select only the beam that will match the rf phase acceptance of the 35.58 MHz cyclotrons. The injector has been nearly continuous and with no failures since June 2003.
Ion generation via resonantly enhanced two-photon ionization
Authors: Knyazev B. A.
Published: May 2004

The charge-exchange method is now one of the main techniques for ion injection into accelerators and storage rings. Disadvantages of conventional methods, based on the atom or ion stripping at the material target, are growth emittance and energy struggling. In this article a variant of stripping technique based on the resonantly enhanced two-photon ionization is considered. The technique allows ionization of singly charged ions of the elements from helium to bismuth. It has absolute selectivity and produces ions only of the next ionization stage. The technique can also be employed for proton injection. Numerical examples are given for several elements.
Development of a compact cesium-seeded magnetically confined plasma ion source for accelerator mass spectrometry
Authors: Tumey Scott J. , Mignerey Alice C. , Grabowski Kenneth S. , Knies David L. , Leonhardt Darrin
Published: May 2004

A gas-fed negative ion source for use in an accelerator mass spectrometry system has been built at the United States Naval Research Laboratory. This ion source is a filament driven plasma ion source using a multicusp magnet arrangement for plasma confinement. Our specific design was assisted by modeling using the SIMION code to optimize beam extraction optics. In addition to the ion source modeling, preliminary characterization of the plasma behavior was performed, which showed the typical and expected order of magnitude increase in collected plasma current when a multicusp magnetic arrangement is employed versus the case with no magnets. Future work will involve implementing a Langmuir probe for more detailed characterization of the plasma, investigation of the effects of using a symmetric rather than a multicusp magnet arrangement, and ultimately the extraction and characterization of ion beams from the source.
Coherent population trapping method of studying magnetohydrodynamic instabilities in a plasma, confined in a magnetic trap
Authors: Akhmedzhanov R. A. , Zelensky I. V. , Kolesov R. L. , Kuznetsova E. A. , Zorin V. G.
Published: May 2004

In magnetic traps of electron cyclotron resonance (ECR) sources of multicharged ions not utilizing the minimum |B| magnetic structure, the magnetohydrodynamic instability is likely to develop. A local laser induced fluorescence-type magnetic field diagnostics based on coherent population trapping effect may help in the study of the instability. Theoretical estimates presented in the article show that parameters of plasmas in ECR sources of multicharged ions satisfy the conditions at which the diagnostic works.
Comparison of different extraction and acceleration systems for a high intense proton beam for the future proton linac at GSI
Authors: Hollinger R. , Spädtke P.
Published: May 2004

For the injection into the future proton LINAC at GSI, the ion source and low energy beam transport system has to deliver a 100 mA proton beam with approximately 100 keV at the entrance of the radio frequency quadrupole within an acceptance (normalized, rms) of 0.2 π mm mrad. The proton yield provided by the ion source should be 90% or higher, whereas the emittance should be as small as possible. The article presents the results of computer simulations done with AXCEL-INP for three different extraction and acceleration systems: a compound system, a pentode extraction system, and a combination of a triode extraction system followed by a separately screened dc acceleration system. These systems will be discussed in terms of beam brightness and facile handling for beam time operation.
Multiple ionization of metal ions by ECR heating of electrons in vacuum arc plasmas
Authors: Vodopyanov A. V. , Golubev S. V. , Zorin V. G. , Razin S. V. , Vizir A. V. , Nikolaev A. G. , Oks E. M. , Yushkov G. Yu.
Published: May 2004

A joint research and development effort has been initiated, whose ultimate goal is the enhancement of the mean ion charge states in vacuum arc metal plasmas by a combination of a vacuum arc discharge and electron cyclotron resonance (ECR) heating. Metal plasma was generated by a special vacuum arc mini-gun. Plasma was pumped by high frequency gyrotron-generated microwave radiation. The results have demonstrated substantial multiple ionization of metal ions. For a lead plasma, ECR heating increased the maximum attainable ion charge state from Pb2+ up to Pb6+. The confinement parameter was as high as ∼109 cm−3 s. Further increase of the ion charge states will be attained by increasing the vacuum arc plasma density and optimizing the ECR heating conditions.
Theoretical modeling of an A6 relativistic magnetron
Authors: Kaup D. J.
Published: May 2004

The analytical modeling of the initialization stage of a relativistic magnetron of the A6 cylindrical design is presented, where only two dominant modes are used: a direct current (dc) background mode and a radio frequency (rf) pump mode. These two modes interaction nonlinearly, with the dc background being driven by the dc electromagnetic forces and the ponderomotive forces of the rf mode, while the rf mode is the most unstable linear eigenmode on this dc background. In cylindrical geometry, the diocotron resonance is found to occur over a broader region than in planar models. In fact, in certain parameter regimes, the resonance can appear twice, once near the Brillouin edge, and second, just below the anode. In these parameter regimes, the oscillating electrons can be accelerated twice. Numerical results for the initiation stage agree quite well with the known experimental results on the A6. Results for 350 kV are emphasized, and similar results have also been obtained for voltages between 300 and 500 kV. Numerical data are presented that indicate a possible source for a nonlinear instability, which could give rise to pulse shortening, in the later operating stage, where the device should be smoothly delivering power.