bluuebunny/crossref_metadata_2025 huggingface dataset:
High intensity beams from electron cyclotron resonance ion sources: A study of efficient extraction and transport system (invited)
Authors: Gammino S. , Ciavola G. , Celona L. , Andò L. , Passarello S. , Zhang X. Zh. , Spädtke P. , Winkler M.
Published: May 2004

A study of the design of extraction and transport system for high intensity beams that will be produced by the next generation electron cyclotron resonance ion source (ECRIS) was carried out in the frame of a European collaboration devoted to the definition of the main parameters of third generation ECRIS. High intensity production tests carried out in the previous years at INFN-LNS have shown evidence for the need to review the main concepts of the beam analysis and transport when high currents of low energy highly charged ions are extracted from the source. The transport of such low energy beams becomes critical as soon as the total current exceeds a few mA. The study reported here is based on the calculated parameters for the GyroSERSE source and the computer simulations have been carried out to obtain low emittance beams. The design of the extraction system was carried out by means of the KOBRA (three dimensional) code. The study of the beam line has been carried out with the codes GIOS, GICO, and TRANSPORT by taking into account both the phase space growth due to space charge and to the aberrations inside the magnets. The description of some different beam line options will be also given.
Sophisticated computer simulation of ion beam extraction for different types of plasma generators
Authors: Spädtke Peter
Published: May 2004

Various plasma generators are used to generate the necessary particle density for extraction of an ion beam with required performance. For the simulation the distribution of ions and electrons in real space and momentum space has to be taken into account to get a realistic description of ion beam formation. In addition, the charge state distribution influences the quality of the extracted beam by undesired space charge effects if magnetic fields are acting on the ions.
Atomic fraction of hydrogen plasma in a negative hydrogen ion source
Authors: Wada M. , Kasuya T. , Takahashi H. , Takemoto T.
Published: May 2004

Hydrogen atoms effusing out from an extraction hole of a 6 cm diam and 6 cm long ion source was measured using a quadrupole mass spectrometer coupled to a neutral beam chopping system. The system background for atomic signal detection was negligible. As the discharge current was increased, the signal of atomic hydrogen increased almost linearly with the discharge current. Meanwhile the signal of molecular hydrogen slightly decreased with increasing discharge current. The signal to noise ratio of the present system is as low as 1/80 for typical operation of the ion source. The status of the system modifications to reduce residual hydrogen gas is reported.
The design of high power, external antennas for radio frequency multicusp ion sources
Authors: Welton R. F. , Stockli M. P. , Roseberry R. T. , Kang Y. , Keller R.
Published: May 2004

The ion source for the Spallation Neutron Source (SNS) is a radio-frequency, multicusp source designed to deliver H− beam pulses of 45 mA to the SNS accelerator, with a pulse length of 1 ms and a repetition rate of 60 Hz. In order to achieve this performance the source must operate with both high peak rf power, ∼45 kW, and high average rf power, ∼3 kW, over an operational run period of 3 weeks. The most critical source component in this respect is the plasma-immersed, porcelain coated rf antenna which can be susceptible to damage during high power operation. The DESY group has developed an external antenna configuration utilizing an Al2O3 plasma chamber which has demonstrated a very long operational period exceeding 25 000 h. Their source operates with peak rf powers comparable to the SNS source but with greatly reduced average rf powers, ∼50 W. In order to explore the applicability of this external antenna concept to high average power ion sources like the SNS source, we have performed thermal, mechanical, and electromagnetic analyses of the Al2O3 plasma chamber. This article discusses the final design which has resulted from these studies as well as estimates of the power limitations of such devices.
Numerical investigation for high intensity H− beam injection to a 100 MeV compact cyclotron
Authors: Zhang Tianjue , Yao Hongjuan , Guan Xialing , Chu Chengjie , Zhong Junqing , Yin Zhiguo
Published: May 2004

As a part of the Upgrade Project of Beijing Tandem Accelerator Laboratory, a 100 MeV compact cyclotron was designed for the generation of high intensity proton beam. In comparison the H− beam intensity injected into the cyclotron central region of the 30 MeV medical cyclotron developed at CIAE 8 years ago, those injected into the 100 MeV machine will be 4 times higher. So, the axial injection optics was investigated numerically again by means of taking the space charge effect into account. The simulation started from the old layout based on the ES (Einzell lens and solenoid) system in CIAE’s 30 MeV machine and SQQ system (solenoid and doublet) in TRIUMF’s machine, shows that a ESQQ system should be able to match the injection optics better for higher intensity beam injection. A new layout based on ESQQ injection system will be used for the 100 MeV cyclotron. From three-dimensional field computation, the modularization of magnets (S and QQ) are designed so that the injection line ESQQ could be rearranged flexibly.
Direct current H− source for the medicine accelerator (invited)
Authors: Belchenko Yu. , Savkin V.
Published: May 2004

A compact cw hydrogen negative ion source having reliable operation and a simplified maintenance is developed at Budker Institute of Nuclear Physics for a tandem accelerator of boron capture neutron therapy installation. The source uses a Penning discharge with a hydrogen and cesium feed through the hollows in the cathodes. Discharge voltage is about 60–80 V, current 9 A, hydrogen pressure 4–5 Pa, magnetic field 0.05–0.1 T, and cesium seed <1 mg/h. Negative ions are mainly produced on the cesiated anode surface due to conversion of hydrogen atoms. An optimal anode temperature is 250–350 °C. Negative ion beam current is directly proportional to the discharge current and to the emission hole area. A triode system for the beam extraction and acceleration system is used. The flux of accompanying extracted electrons was decreased by filtering in the transverse magnetic field. This electron flux was intercepted to the special electrode, biased at 4 kV potential with respect to the anode. Source stable cw operation for several hour runs was multiply tested. A H− ion beam with current up to 8 mA, beam energy 23 keV was produced regularly. Negative ion current of heavy impurities had a value of about 3% of the total beam current. Beam normalized emittance is about 0.3 π mm mrad and emission current density −0.1 A/cm2. A built-in cathode heater provides the operation quick start.
Surface production dominating Cs-free H− ion source for high intensity and high energy proton accelerators
Authors: Ueno Akira , Ikegami Kiyoshi , Kondo Yasuhiro
Published: May 2004

A Cs-free negative hydrogen (H−) ion source driven by pulsed arc plasma with a LaB6 filament is being operated for the beam tests of the Japan Proton Accelerator Research Complex (J–PARC) linac. A peak H− current of 38 mA, which exceeds the requirement of the J–PARC first stage, is stably extracted from the ion source with a beam duty factor of 0.9% (360 μs×25 Hz) by principally optimizing the surface condition and shape of the plasma electrode. The sufficiently small emittance of the beam was confirmed by high transmission efficiency (around 90%) through the following 324 MHz 3 MeV J–PARC radio frequency quadrupole linac (M. Ikegami et al., Proc. 2003 Part. Accel. Conf. 2003, p. 1509). The process of the optimization, which confirms the validity of hypothesis that H− ions are produced by surface reaction on a Mo plasma electrode dominantly in the ion source, is presented.
Studies of H− source for large helical device-neutral beam injector (invited)
Authors: Oka Y. , Tsumori K. , Takeiri Y. , Ikeda K. , Kaneko O. , Nagaoka K. , Osakabe M. , Asano E. , Kawamoto T. , Kondo T. , Sato M. , Grisham L. , Honda A. , Umeda N. , Yamamoto T.
Published: May 2004

A powerful neutral beam system with six high current H− ion sources achieved a total power of 10.3 MW in the large helical device (LHD). We describe the present status of the ion sources, and the results of studies of cesium consumption, tungsten filament lifetime, and the velocity spectrum of the beam. Maximum power and beam energy in those ion sources range from 3.5 to 4.4 MW and 165 to 180 keV (design energy), respectively. The maximum H− current is ∼25 A. Much progress on beam acceleration and plasma uniformity was facilitated by a new accelerator and new arc power supply system with careful Cs seeding. Cs consumption for 1/2 year of operation ranges from 3.9 to 10.6 g per one source (over 2×104 shots). It is converted to the rate of 0.17–1.5 mg per one shot per source. It is considered that Cs deposition on the inside surface of the plasma source could be from 0.11 to 1.0 monolayer per one shot per source. This is of the same order as the expected optimum coverage of ∼0.7. Filament weight loss was measured in each source. Filaments have to be exchanged every 1–3 months (i.e., ∼104 shots). The filament lifetime cycle, instead of the Cs consumption, determines the maintenance cycle. Distribution of the filament weight loss in each source is nonuniform. The distribution changed after adjusting the arc current distribution to each filament for optimized H− uniformity by an independently adjustable multiarc power supply system and filament supplies. Tungsten deposition is from 0.015 to 0.065 monolayer per shot per source. This is smaller than the Cs deposition. Doppler shift spectroscopy yielded the first velocity spectrum for the LHD-neutral beam injector beam.
A radioactive target/ion source for material research
Authors: Cui B. , Li L. , Ma Y. , Wang R. , Jiang W.
Published: May 2004

A radioactive target/ion source for material research has been developed at China Institute of Atomic Energy, China. With a proton ion beam from the HI-13 tandem as the primary beam, the low intensity radioactive ion beam is generated on line. The first aim of the source is to produce a radioactive ion beam of Zn+62 which will serve as nuclear probe in material research. The main features and current status of the source are presented in this article.
High power hydrogen neutral beam injector with focusing for plasma heating
Authors: Deichuli P. P. , Davydenko V. I. , Ivanov A. A. , Korepanov S. A. , Mishagin V. V. , Sorokin A. V. , Stupishin N. V. , Shulzhenko G. I.
Published: May 2004

High power neutral beam injector has been developed with particle energy of 25 keV, a current of 60 A, and several milliseconds pulse duration. Six of these injectors are planned to be used for the upgrade of the neutral beam system of a gas dynamic trap device. The injector ion source is based on an arc-discharge plasma box. The plasma emitter is produced by a 1 kA arc discharge in hydrogen. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increase its efficiency and improve homogeneity of the plasma emitter. The ion beam is extracted by a four-electrode ion optical system (IOS). Initial beam diameter is 200 mm. The grids of the IOS have a curvature for geometrical focusing of the beam. The optimal IOS geometry and grid potentials were calculated to provide precise beam formation. The measured angular divergence of the beam is 0.02 rad, which corresponds to the measured width of the beam profile at a focal point of 2.5 cm.
Acceleration of 1 MeV, 100 mA Class H− ion beams in a proof-of-principle accelerator for ITER
Authors: Inoue T. , Taniguchi M. , Dairaku M. , Hanada M. , Kashiwagi M. , Morishita T. , Watanabe K. , Imai T.
Published: May 2004

Development of an electrostatic accelerator for 1 MeV, 1 ampere class H− ion beams has been carried out as a Proof-of-Principle (PoP) of high current accelerators required in neutral beam system of fusion reactors such as ITER. A unique feature of such fusion oriented accelerators is to utilize vacuum insulation not only inside but also outside of the accelerator for high voltage insulation, since conventional gas insulation is not applicable due to excess radiation induced conductivity in the gas. The PoP accelerator is surrounded by an insulator stack as a vacuum boundary with a vacuum gap of 50 mm all around the accelerator. One of the key technologies to achieve insulation of MV voltage was reduction of electric field strength at triple junction of the insulator (made of FRP, fiber reinforced plastic) stack. By lowering the stress to 1.7 kV/mm, the accelerator sustained 1 MV stably for more than 2 hours. By tuning the ion source with/without cesium under stable accelerator operation, the PoP accelerator generated H− ion beams of 70 mA at 1 MeV, and 110 mA (80 A/m2) at 900 keV stably for several hundreds shots (pulse length, 0.5–1 s limited by the target). The dark current flowed inside/on the surface of the FRP insulator due to photoelectron effect was estimated to be less than μA in case of 0.1 A electron beam acceleration (maximum current observed in the experiment). This is in the same order to that due to conductivity of the insulator material. So far, high voltage breakdown due to photoelectron has never been observed.
Characterization of ion species mix of the TEXTOR diagnostic hydrogen beam injector with a rf and arc-discharge plasma box
Authors: Ivanov A. A. , Deichuli P. P. , Kreter A. , Maximov V. V. , Schweer B. , Shikhovtsev I. V. , Stupishin N. V. , Usoltsev D. V. , Podminogin A. A. , Uhlemann R.
Published: May 2004

The ion specie fractions of the diagnostic hydrogen beam of TEXTOR tokamak have been determined by making use of a Hα-light Doppler shift spectroscopy and alternatively by a magnetic mass spectrometer. The measurements were done for the fixed beam energy of 50 keV and beam current variable up to 2.5 A. According to the measurements, the full energy beam component is for a radio frequency plasma box ∼50% by the particle density and more than 75% for an arc-discharge plasma box.
Development of a compact helicon ion source for neutron generators
Authors: Jung H. D. , Park M. J. , Kim S. H. , Hwang Y. S.
Published: May 2004

A compact helicon ion source has been designed for a neutron generator. Energetic deuterium beams of 120 keV from this ion source will be directed onto a Ti-coated copper target where D–D nuclear fusion reactions take place and generate 108 n/s of neutrons. High-density radio frequency (rf) plasma sources such as a helicon plasma source, known for its highest efficiency of generating high-density plasmas, are chosen for the development of a high-current density compact ion source. Highest plasma densities for hydrogen plasmas are obtained at relatively low magnetic fields of 100–300 G although plasma densities of helicon plasmas are well known to be almost linearly dependent on magnetic field strength. With Nagoya type III antenna, plasma densities of up to 2×1011 cm−3 are obtained with 1.1 kW rf power at the frequency of 13.56 MHz. With the prototype helicon ion source, hydrogen beam currents of up to 44 mA at 23 kV have been extracted in continuous wave operations with the beam current density of 28.5 mA/cm2. With helical antenna instead of Nagoya type III antenna, higher plasma densities of up to 1012 cm−3 are obtained and open up a new possibility of much higher beam current densities.
Mass analyzer “MASHA” high temperature target and plasma ion source
Authors: Semchenkov A. G. , Rassadov D. N. , Bekhterev V. V. , Bystrov V. A. , Chizov A. Yu. , Dmitriev S. N. , Efremov A. A. , Guljaev A. V. , Kozulin E. M. , Oganessian Yu. Ts. , Starodub G. Ya. , Voskresensky V. M. , Bogomolov S. L. , Paschenko S. V. , Zelenak A. , Tikhonov V. I.
Published: May 2004

A new separator and mass analyzer of super heavy atoms (MASHA) has been created at the FLNR JINR Dubna to separate and measure masses of nuclei and molecules with precision better than 10−3. First experiments with the FEBIAD plasma ion source have been done and give an efficiency of ionization of up to 20% for Kr with a low flow test leak (6 particle μA). We suppose a magnetic field optimization, using the additional electrode (einzel lens type) in the extracting system, and an improving of the vacuum conditions in order to increase the ion source efficiency.
High intensity alkali ion sources for plasma diagnostics
Authors: Bondarenko I. S. , Chmyga O. O. , Dreval M. B. , Khrebtov S. M. , Komarov O. D. , Kozachok O. S. , Krupnik L. I. , Nedzelskiy I. S. , Schweinzer J.
Published: May 2004

The injection systems of heavy ion beam probe (HIBP) and beam emission spectroscopy plasma diagnostics must produce a beam with a high enough intensity to obtain a reliable secondary signal. In particular, it can be achieved by improvements and optimization of the ion sources. Among a variety of them, the sources with solid-state thermoionic emitters have strong advantages in simplicity and very small (0.1–1 eV) initial energy dispersion. High intensity alkali ion sources with solid-state thermoionic emitters of Li+, Na+, K+, Cs+, and Tl+ have been developed and investigated in IPP NSC “KIPT,” Kharkov, Ukraine. In a steady mode of operation the current densities up to 6 mA/cm2 are obtained with an emitter capacity up to 9 mA/h. With no significant design modifications, these ion sources are used on currently operating injectors of HIBP diagnostics on the TJ-II stellarator (Spain), tokamaks T-10, TUMAN-3M (Russia), and ISTTOK (Portugal), and the injector of the BES diagnostic on ASDEX-U tokamak (Germany).
Progress in the development of rf driven H−/D− sources for neutral beam injection
Authors: Kraus W. , Bandyopadhyay M. , Falter H. , Franzen P. , Heinemann B. , McNeely P. , Riedl R. , Speth E. , Tanga A. , Wilhelm R.
Published: May 2004

Recent experiments with a radio frequency (rf) driven ion source for the production of negative hydrogen ions have shown that the previously observed improvement in the H− ion current by the admixture of argon is a beam optics effect, rather than an ion production effect. The plasma flow from the driver to the expansion volume causes a pressure gradient in the source. In a caesiated source the efficiency is no longer a function of the source pressure, but low pressure operation is limited by rf coupling. Using an internal coil to provide the filter field required in negative ion sources has no negative effect on source efficiency.
New operational beam for the CERN heavy ion program
Authors: Chamings J. , Coco V. , Hill C. E. , Küchler D. , Lombardi A. , O’Neil M. , Scrivens R.
Published: May 2004

After 9 yr of delivering lead ions to the SPS fixed target physics program, a new beam was requested for the 2003 physics period, namely indium. The operational requirements and present status of the source will be presented together with the solutions to some of the problems experienced.
MONO1001: A source for singly charged ions applied to the production of multicharged fullerene beams
Authors: Maunoury L. , Andersen J. U. , Cederquist H. , Huber B. A. , Hvelplund P. , Leroy R. , Manil B. , Pacquet J. Y. , Pedersen U. V. , Rangamma J. , Tomita S.
Published: May 2004

The present article reports on a recent study of the production of multiply charged fullerene beams based on an electron cyclotron resonance (ECR) ion source (ECRIS). As collision studies in fundamental physics are demanding intense beams of multiply charged ions of small molecules, clusters, and particularly of fullerenes, we have further developed the ion source ECRIS MONO1000 [P. Jardin et al., Rev. Sci. Instrum. 73, 789 (2002)], originally devoted to produce singly charged ions, towards the production of multiply charged fullerene beams. In this article, the test measurements performed at the Electrostatic Ion Storage Ring Århus rf power (ELISA) facility will be described. Typical mass spectra (from pure C60 and C70 powder) will be shown and the influence of several source parameters (rf power, support gas, gas pressure,…) will be discussed specifying the conditions necessary for an optimum ion source operation.
Microwave plasma source as an ion beam neutralizer
Authors: Medhisuwakul M. , Boonyawan D. , Vilaithong T. , Engemann J.
Published: May 2004

A 13.56 MHz radio-frequency (rf) driven multicusp ion source has been developed at the Fast Neutron Research Facility. An argon ion current density of 29 mA cm−2 can be obtained for argon gas at a pressure of 0.4 Pa, rf power of 500 W and extraction voltage of 3 kV. For such a low energy and high current of several milliampere ion beam, additional low energy electrons are needed to suppress the unwanted beam broadening by the low energy Ar+ ions. This can be achieved by injecting additional electrons into the Ar+-ion beam. An in-waveguide microwave plasma source, operating at a frequency of 2.45 GHz, has been constructed based on the design of Korzec et al. [D. Korzec, A. Muller, and J. Engemann, Rev. Sci. Instrum. 71, 800 (2000)], at Wuppertal. An electron current of up to 250 mA can be extracted from the source, at an absorbed microwave power of 90 W, a pressure of 8×10−2 Pa, and an extraction voltage of 50 V. The neutralization source is installed downstream close to the beam line. By electrostatic interaction the plasma electrons are attracted to the positively charged ion beam forming a beam envelope. To investigate the neutralization effect, the ion extractor is modified to produce a parallel beam. A fluorescent beam profile monitor is used to measure the beam size in both cases; with and without the neutralizer. The profile of the beam can give information about the effect of the neutralizer on the ion beam. The beam current was also measured by using a Faraday cup. Results of the measurements will be presented and discussed.
High brightness rf ion source for accelerator-based microprobe facilities
Authors: Mordyk S. N. , Voznyy V. I. , Miroshnichenko V. I. , Ponomarev A. G. , Storizhko V. E. , Sulkio-Cleff B.
Published: May 2004

The article discusses possible ways of increasing beam brightness in radio frequency (rf) ion sources. The characteristics of rf ion sources with different permanent magnet systems are investigated. Experiments were performed with argon and helium gases. A beam brightness of ∼100 A/(m2 rad2 eV) was attained at a plasma density of 3×1011 cm−3 for argon and 1×1011 cm−3 for helium. The ion current density inside an emission hole with 0.6 mm diameter of was 10 mA/cm2 for rf power input into the plasma of 40 W (frf=27.12 MHz). Measurements of the current value and emittance were performed with an ion source test facility permitting measurements of the current, emittance, ion beam mass composition, and rf power input into the plasma.
Compact ECR ion source with permanent magnets for carbon therapy
Authors: Muramatsu M. , Kitagawa A. , Sakamoto Y. , Sato Y. , Yamada S. , Ogawa H. , Drentje A. G. , Biri S. , Yoshida Y.
Published: May 2004

Ion sources for the medical facilities should have the following characteristics of easy maintenance, low electric power, good stability, and long operation time without trouble (1 year or longer). For this, a 10 GHz compact electron cyclotron resonance ion source (ECRIS) with all permanent magnets was developed. The beam intensity and stability for C4+ were 280 e μA and better than 6% during 20 h with no adjustment of any source parameters. These results were acceptable for the medical requirements. Recently, many plans were proposed to construct the next generation cancer treatment facility. For such a facility we have designed an all permanent magnet ECRIS, in which a high magnetic field is chosen for increasing the beam intensity. The maximum mirror magnetic fields on the beam axis are 0.59 T at the extraction side and 0.87 T at the gas injection side, while the minimum B strength is 0.25 T. The source has a diameter of 32 cm and a length of 29.5 cm. Details of the design of this source and its background are described in this article.
Oceans circulation and electron cyclotron resonance sources: Measurement of the AR-39 isotopic ratio in Seawater
Authors: Gaelens M. , Loiselet M. , Ryckewaert G. , Pardo R. C. , Scott R. H. , Vondrasek R. , Collon Ph. , Kutchera W.
Published: May 2004

The radionuclide Ar39 is produced in the atmosphere by cosmic rays and has an isotopic abundance of 8.1×10−16. Because its half life (T1/2=269 years) is well matched to the time periods involved in the oceanic currents around the Earth, the measurement of the Ar39 isotopic ratio is an ideal tool to date ocean water from different depths. It would complement the information gained by the C14 measurements (T1/2=5730 years). However, the measurement of the isotopic ratio Ar39/Ar40 is a technical challenge: 1 L of modern ocean water contains ∼6500 atoms of Ar39, and produces ∼17 decays per year. Although it has been possible to detect the Ar39 decays in large volumes of sea water by using the low level counting technique, the possibility of measuring the number of Ar39 atoms faster and in smaller samples using the accelerator mass spectrometry (AMS) technique would be a major breakthrough for this type of measurement. The development of a viable AMS method for Ar39 has been underway for several years at Argonne National Laboratory, and is presently hampered by the presence of stable K39 ions coming from the ion source. Although the intensity of this isobaric contaminant is low (∼pA extracted from the source), it has to be compared with the Ar39 beam intensity (atoms per minutes). In order to separate these two beams (whose mass difference is only 1.6×10−5), the intensity of the K39 beam coming from the ion source has to be reduced by several orders of magnitude. This reduction has been investigated both at Argonne National Laboratory and at Louvain-la-Neuve. Two techniques have been tried out. In the first, a quartz liner is used to provide a clean surface, while in the second these impurities are buried in a SiO2 layer formed in situ by running the source with a mixture of silane and oxygen. The K39 background has been reduced by a factor of 100 with these treatments. These techniques and their results obtained both at Argonne and Louvain-la-Neuve will be presented. The ion source specific requirements for this type of application will also be discussed.
High current density ion beam formation from plasma of electron cyclotron resonance discharge
Authors: Zorin V. , Golubev S. , Razin S. , Sidorov A. , Skalyga V. , Vodopyanov A.
Published: May 2004

This article describes the research effort to obtain a quality ion beam with high currents from the dense plasma of the pulsed electron cyclotron resonance discharge pumped with high-power millimeter-wave radiation. The results of the experiments aimed at optimization of the two-electrode system for ion extraction are presented. Under the conditions, when the density of the ion current in the vicinity of the plasma electrode was 65–75 mA/cm2, the normalized emittance of the ion beam did not exceed 0.19 π mm mrad.
Recent results with Au ions from a multiampere electron beam ion source at Brookhaven National Laboratory (invited abstract)
Authors: Beebe E. N. , Alessi J. G. , Graham D. , Kponou A. , Pikin A. , Prelec K. , Ritter J. , Zajic V.
Published: May 2004

An electron beam ion source (EBIS) that would satisfy Relativistic Heavy Ion Collider (at Brookhaven National Laboratory) (RHIC) requirements should be capable of producing intensities of, e.g., Au32+ ions of about 3×109 particles/pulse in 10–40 μs pulses. The total charge extracted (all charge states) would be 85 nC, assuming 20% in the peak charge state. To achieve this at Brookhaven National Laboratory, pulsed-electron beam currents up to 10 A, 100 ms are being used. A test EBIS has been constructed, designed for the full electron beam power and having close to half of the trap length of an EBIS for RHIC. As a result of successful experiments on the test EBIS, we are confident that an EBIS meeting RHIC requirements can be built. Initial electron beam tests have demonstrated a 100 ms, 8.6 A electron beam through the EBIS trap. The stable operation of 10 A, 50 ms electron beams through the EBIS trap has also been achieved. Gold spectra with a dominant charge state 34+ and total ion charge 55 nC measured on a current transformer have been obtained at the EBIS exit after a 30 ms confinement period. Recent studies with an in-line time-of-flight spectrometer with measurement of charge on a Faraday cup have shown 83% of the >28 nC extracted charge to be Au ions peaked at Au25+, for a 7 A electron beam and 10 ms confinement period. Typical normalized rms emittance values using a 6.8 A electron beam, 20–40 nC total ion charge, and 1–3 mA extracted ion current have been in the range of 0.08–0.1 π mm mrad. An energy analysis of the total extracted ion pulses >35 nC has indicated a longitudinal energy spread of <2 kV full width at half maximum after a 35 ms confinement period using a 7 A electron beam. Most design goals have been exceeded and much of the present work is geared toward improving reliability and providing larger safety margins. These include upgrading the electron gun, decoupling the electron beam launch energy from the electron collection energy, and tailoring the magnetic fields to reduce electron beam losses. Details of these measurements, tests in progress to improve performance, and plans for optimizing the design of the RHIC EBIS will be presented.
Development of a Be-7 beam: Techniques for the ionization of radioactive metallic elements (abstract)
Authors: Gaelens M. , Loiselet M. , Ryckewaert G.
Published: May 2004

The Louvain-la-Neuve ECR ion source is used to ionize metallic radioactive elements like Be-7 (T1/2=53d) for postacceleration in its radioactive beam facility. Because of the minute quantities of primary material available, dedicated techniques had to be developed to inject the radioactive atoms in a controlled manner and to recycle the atoms lost on the plasma chamber walls. For this purpose, a heated plasma chamber has been constructed which allows the use of “on-line chemistry in the source” to effectively recycle the deposited material. The presence of a radioactive tracer proved to be a strong diagnostic tool to locate the material loss in the different parts of the source. This development resulted in the production of a postaccelerated beam of Be-7 in 1+ and 2+ charge states. Up to 110 h of continuous beam have been provided with primary material quantities of a few ng. The total efficiency of the source reached a few percent. These beams were initially developed for experiments in nuclear physics. The implantation of Be-7 is now also used as a powerful tool to measure the wear properties of various materials like ceramics and amorphous carbon layers. This will be illustrated with a few examples.
Zinc isotope discrimination effect in inductively coupled plasma mass spectrometer
Authors: Suzuki T. , Kanzaki C. , Nomura M. , Fujii Y.
Published: May 2004

Inductively coupled plasma mass spectrometry (ICPMS) has recently been used for isotope ratio analysis. The isotope discrimination effect in the mass spectrometer is a primary factor contributing to loss of precision and accuracy in isotope ratio analysis. The discrimination effect of zinc isotopes was investigated by comparing the results obtained using a quadrupole type ICPMS with those obtained using a thermal ionization mass spectrometer.
H
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cusp source development for 100 MeV compact cyclotron at China Institute of Atomic Energy
Authors: Zhang Tianjue , Li Zhenguo , Chu Chengjie , Wu Longcheng , Zhong Junqing , Jiao Chuanrong , Ge Tao , Pan Gaofeng , Guan Fengping
Published: May 2004

As a part of the Upgrade Project of Beijing Tandem Accelerator Laboratory, a 100 MeV compact cyclotron was designed for the generation of high intensity proton beams. Due to the limit of acceptance by the cyclotron central region, a new H− cusp source was developed at China Institute of Atomic Energy. The design of this new source is based on TRIUMF’s experience. More than 10 mA of H− beam with a measured emittance of 0.65 π mm mrad are obtained at a voltage of 28 kV from an extraction hole of 11 mm in diameter. In this article, the structure of the source, the magnetic field configuration of the multicusp and virtual filter, the extraction optics, the test results, and future improvements will be described.
Ion sources and low energy beam transport for the new superconducting injector linac for COSY/Jülich
Authors: Gebel R. , Felden O. , von Rossen P.
Published: May 2004

The Institut für Kernphysik of the Forschungszentrum Jülich GmbH has been designing and developing a new injector for the cooler synchrotron COSY. To reach the set goal, the projected linac injector will have to be equipped with new ion sources. One ion source will deliver unpolarized; the other polarized H− or D− pulsed beams in the mA range having an energy of 25 keV. Pulses of up to 500 μs in width and repetition rates up to 2 Hz are foreseen. Several arrangements of the ion sources and the low energy beam transport system have been investigated. The principles guiding the layout of the low energy beam transport are discussed. First operational results of the source for unpolarized H− and D− are discussed.
Improvement of the yield of highly charged ions by a gas-pulsing technique and the current status of the NIRS Penning source
Authors: Miyata Tomohiro , Miyoshi Tomohiro , Sakuma Tetsuya , Yamamoto Mitsugu , Kitagawa Atsushi , Muramatsu Masayuki , Sato Yukio
Published: May 2004

The yields of highly charged ions have been improved by using a gas-pulsing technique in the pulsed Penning-ionized-gauge ion source (PIGIS) in the heavy-ion medical accelerator in Chiba. So far, this pulsed PIGIS has been operated under a low-duty factor (10−2–10−3), in which the gas flow is not being pulsed. A solenoid-type gas valve, having a simple structure compared to the piezo-electric type, was attached to the outside of the PIGIS chamber in order to control the gas flow into the PIGIS chimney. Beam tests for Ne with gas pulsing showed that the pressure response time should actually be a few tens ms, and the intensity of Ne6+ was increased by ten times, from 20 to 200 eμA. The gas pulsing also improved the average vacuum in the low energy beam transport (LEBT) line by a factor of 4. When producing H2+, H3+, and He1+ by PIGIS with gas pulsing, the beam loss of highly charged ions from electron cyclotron resonance ion sources in the LEBT was reduced to be negligible; meanwhile, it was around 30% without gas pulsing. This paper describes the gas-pulsing technique and the preliminary results, as well as some recent developments in the NIRS-PIGIS.
Selenium cluster formation using a new corona discharge-assisted cluster ion source
Authors: Kawai Yoko , Okada Yoshiki , Orii Takaaki , Takeuchi Kazuo , Yamaguchi Satoru
Published: May 2004

A new cluster ion source utilizing corona discharge was studied. Selenium (Se) vapor was ionized by primary nitrogen ions that were generated by corona discharge. We ionized selenium at the first stage of the cluster ion generation process. The selenium ions in the evaporation chamber can, in principle, promote the cluster growth. We observed cluster ions, Sen+ (n=2–4) at 150–280 °C, with a pressures range of 240–430 Torr in the corona discharge chamber. The cluster intensities were found to be maximum at a pressure of 300–370 Torr. It was also found that the cluster intensities slowly increased with the temperature. Based on these results, we discuss the cluster ion formation processes.
Nanocluster ion source by plasma-gas aggregation
Authors: Imanaka Masashi , Katayama Takeshi , Ohshiro Yukimitsu , Watanabe Shin-ichi , Arai Hideyuki , Nakagawa Takahide
Published: May 2004

We are constructing and developing a new type cluster ion source and a detection system. The new cluster ion source consists of a large area plasma source and gas aggregation cell instead of present cluster ion source configuration (magnetron ion source and gas aggregation cell). In new type cluster ion source we adopted a pulsed high-power microwave type plasma source for production of ions and neutral particles. This source can produce dense and stable plasma independent of shape or properties of the sample, and additionally it can produce large sizes of plasma, so that whole area of the sample is sputtered. This feature allows us to produce an intense beam of cluster ions stably compared to the present ion source.
Radioactive ion beam production at GANIL: Status and prospectives (invited) (abstract)
Authors: Leroy R.
Published: May 2004

During the last ICIS in Oakland, we announced that the production of radioactive ion beams on the SPIRAL facility located at GANIL will start before the end of 2001. The production has effectively started and numerous multicharged radioactive ion beams have been delivered for high energy nuclear experiments. This article makes an overview of the different beams that have been produced. In the mean time, an important Research and Development program is continued in order to produce new species of radioactive elements. A new concept of multicharged radioactive production that couple a monocharged ion source, based on the monolithe concept, to an electron cyclotron resonance ion source like Nanogan3 is under developments and is described. The development of monocharged ion sources with high efficiencies is also motivated by a new big project that is under studies at GANIL: the SPIRAL 2 project. The goal of this project consists of extending the disponible radioactive ion beams to very heavy elements created with a new method of production: while the SPIRAL 1 facility uses the projectile fragmentation for radioactive nuclei production, the SPIRAL 2 project is based on the fission of a uranium carbide target induced by a neutron flow created by a high intensity deuton beam. The principle and an overview of the project is presented.
Characteristics of multiantenna rf ion source
Authors: Oka Y. , Shoji T. , Hamabe M. , Sakawa Y. , Suzuki T. , Ikeda K. , Kaneko O. , Nagaoka K. , Osakabe M. , Takeiri Y. , Tsumori K. , Asano E. , Kawamoto T. , Kondo T. , Sato M.
Published: May 2004

A multiantenna rf ion source is studied. The new antenna system is developed to reduce the rf voltage on the antenna compared to that of the conventional loop antenna, which can reduce high voltage rf breakdown on antennas. The antenna was installed in a 1/6 scale ion source for the neutral beam injector (NBI) (H−) used in large helical devices. The characteristics of the ion density current of the plasma produced by using the segmented antennas were studied. A dense plasma with ion saturation current density of 92 mA/cm2 was generated at 45 kW of rf power at 9 MHz for the two-antenna system. At around 10 kW of rf power the plasma density jumped and became a high density mode. The threshold power for the density jump seems to be shifted by the antenna segments and the rf frequency. The current density of the positive ion beam with a small accelerator voltage is 26 mA/cm2 for 10.3 keV of extraction energy, 45 kW of rf power, and 0.16 Pa of plasma source pressure of hydrogen. This multiantenna rf source could potentially be scaled up to the large NBI source.
Preliminary experiments on a laser coupling with an electron cyclotron resonance ion source for trace element analysis
Authors: Sasa Kimikazu , Arai Ichiro , Kurosawa Masanori , Nakagawa Takahide
Published: May 2004

We have developed a laser coupling with an electron cyclotron resonance (ECR) ion source for trace element analysis of mineral samples at University of Tsukuba. A compact Q-switched Nd:YAG laser at 1064 nm wavelength with a pulse width of 8 ns and a maximum energy of 50 mJ is employed to ablate the sample materials as a means of introducing samples into the ECR plasma. Preliminary experiments were performed to focus the laser beam on a pure metallic target (Cu). The mean kinetic energy of the laser produced Cu ions is measured to 470 eV for the laser energy of 50 mJ by a simple time-of-flight method. Design for a laser coupling with an ECR ion source as a new application of mass spectrometry are reported.
Calculation of correlation function of the director fluctuations in cholesteric liquid crystals by WKB method
Authors: Aksenova E. V. , Romanov V. P. , Valkov A. Yu.
Published: May 2004

The spatial correlation functions of the thermal fluctuations in systems with smoothly varying structure are calculated by means of the WKB method. As a particular physical problem we consider the behavior of director fluctuations in cholesteric liquid crystals possessing one-dimensional spatial periodicity. The problem leads to the solution of set of two second order differential equations with periodic coefficients. It is shown that in this physical system there exist regions where the WKB approximation is not valid. The analysis of these regions is similar to that of the turning points in quantum mechanics. Contrary to standard approach in our problem the turning point has fourth-order singularity and only decaying solutions have physical sense. We find WKB solutions for normal modes of director fluctuations in cholesteric liquid crystals far from the turning point as well as in its vicinity. We obtain that two fluctuating modes interact in the vicinity of the turning point, but any of these modes does not produce another. The amplitudes of modes change in such a way the product of amplitudes is constant. As a result we obtain explicit expressions for spatial correlation function in cholesteric liquid crystals with the large pitch which are valid in the entire domain. Finally we discuss the use of the correlation function in light scattering experiments.
Interaction of suprathermal electron fluxes with lower hybrid waves
Authors: Volokitin A. , Krafft C.
Published: May 2004

Several in situ measurements performed in the terrestrial magnetosphere and in the solar wind have evidenced the simultaneous presence of whistlers or lower hybrid waves with suprathermal fluxes or beams of electrons. The so-called fan instability, which can be driven by an anisotropy of the energetic electron velocity distribution along the ambient magnetic field, can play an essential role in space plasmas where energetic electron fluxes are ubiquitous. By destabilizing waves at the anomalous cyclotron resonance, this instability can modify drastically the shape of the parallel velocity distribution and give rise to bumps in the tail. This paper presents a new theoretical model which allows one to describe the nonlinear interaction of a packet of lower hybrid waves with a nonequilibrium electron distribution function. This Hamiltonian self-consistent model, which is based on a semianalytical approach, provides an efficient and original tool to point out new physical features, especially in what concerns the nonlinear stage of the fan instability and its implications for space physics.
On the interaction of vortices with mixing layers
Authors: Vera Marcos , Liñán Amable
Published: May 2004

We describe the perturbations introduced by two counter-rotating vortices—in a two-dimensional configuration—or by a vortex ring—in an axisymmetric configuration—to the mixing layer between two counterflowing gaseous fuel and air streams of the same density. The analysis is confined to the near stagnation point region, where the strain rate of the unperturbed velocity field, A0, is uniform. We restrict our attention to cases where the typical distance 2r0 between the vortices—or the characteristic vortex ring radius r0—is large compared to both the thickness, δv, of the vorticity core and the thickness, δm∼(ν/A0)1/2, of the mixing layer. In addition, we consider that the ratio, Γ/ν, of the vortex circulation, Γ, to the kinematic viscosity, ν, is large compared to unity. Then, during the interaction time, A0−1, the viscous and diffusion effects are confined to the thin vorticity core and the thin mixing layer, which, when seen with the scale r0, appears as a passive interface between the two counterflowing streams when they have the same density. In this case, the analysis provides a simple procedure to describe the displacement and distortion of the interface, as well as the time evolution of the strain rate imposed on the mixing layer, which are needed to calculate the inner structure of the reacting mixing layer as well as the conditions for diffusion flame extinction and edge-flame propagation along the mixing layer. Although in the reacting case variable density effects due to heat release play an important role inside the mixing layer, in this paper the analysis of the inner structure is carried out using the constant density model, which provides good qualitative understanding of the mixing layer response.
Zonal flow and field generation by finite β drift waves: Finite ion temperature effects
Authors: Guzdar P. N. , Kleva R. G. , Chakrabarti N.
Published: May 2004

The generation of zonal flows and zonal fields by finite β drift waves in plasmas with finite ion temperature Ti is investigated. This work extends our earlier work with zero ion temperature. The growth rate of the zonal flow and field is enhanced by finite Ti effects. This leads to a reduction in the critical electron temperature derived earlier for triggering low to high transitions in tokamak plasmas.
Switching of nonneutral plasma diodes. I. Analytic theory
Authors: Ender A. Ya. , Kuznetsov V. I. , Schamel H. , Akimov P. V.
Published: May 2004

The transient nature of the electron beam dynamics in plasma diodes caused by a weak instantaneous switching of the collector voltage is studied analytically. The solution for a pure electron vacuum diode, found recently [P. V. Akimov et al., J. Appl. Phys. 93, 1246 (2003)], is extended to treat the electron dynamics under the influence of an immobile ion background. In this case new branches of equilibria are obtained from which new perspectives for switching between different states can arise. Moreover, the space-charge limit (SCL) of the electrical current, well known for pure electron diodes, can be overcome by an appropriate choice of the branch and of the ion density. It is emphasized that the line of critical SCL points, obtained by a sweep of the collector voltage, coincides with the line of marginal stability of linear perturbations with respect to equilibria without reflection. For the switching analysis use is made of the Laplace transform technique, and a remarkably simple expression for the Laplace-transformed potential perturbation is found. Exact analytical solutions for the time-dependent response of the diode originating from switching are found.
Kinetic theory analysis of the two-surface problem of a vapor–vapor mixture in the continuum limit
Authors: Takata Shigeru
Published: May 2004

A steady flow of a vapor–vapor mixture between two parallel plane condensed phases for small Knudsen numbers is investigated on the basis of the kinetic theory of gases. By a systematic asymptotic analysis of the Boltzmann equation, it is shown that there are two distinct types of behavior of the mixture: the Euler-type behavior and the convection-diffusion-type behavior. Both types of behavior are confirmed numerically for the Boltzmann equation by the direct simulation Monte Carlo method and for the model Boltzmann equation proposed by Garzó, Santos, and Brey by the standard finite-difference method. Finally, the continuum limit (Kn=0+) is considered, and it is shown that the ghost effect that some of the gas rarefaction effects still have an influence in the continuum limit manifests itself in the case of the convection-diffusion-type. This result shows that the infinitesimal jump of pressure at the surface of the condensed phase must be taken into account correctly for the description of the behavior of the vapors in the continuum limit.