## 2007 Vol. 31, No. S1

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2007, 31(S1): 1-7.
Abstract:
The next generation, superconducting ECR ion source VENUS (Versatile ECR ion source for NUclear Science) has operated with 28GHz since 2004, and has produced world record ion beam intensities. The VENUS project is focused on two main objectives. First, for the 88-Inch Cyclotron, VENUS will serve as the third injector source boosting both the energy and intensity of beams available from the facility. Secondly, VENUS also serves as the prototype injector source for a high intensity heavy ion beam driver linac for a next generation radioactive ion beam facility, where the goal is to produce intense beams of medium to low charge states ions such as 240eμA of Xe20+ or 250eμA of U28+to34+. These high intensity ion beam requirements present a challenge for the beam transport system since the total currents extracted from the ECR ion source reach several mA. Therefore in parallel to ion beam developments, we are also enhancing our ion beam diagnostics devices and are conducting an extensive ion beam simulation effort to improve the understanding of the ion beam transport from the VENUS ECR ion source. The paper will give an overview of recent experiments with the VENUS ECR ion source. Since the last ECR ion source workshop in Berkeley in 2004, we have installed a new plasma chamber, which includes X-ray shielding. This enables us to operate the source reliably at high power 28GHz operation. With this new chamber several high intensity beams (such as 2.4mA of O6+, 600eμA of O7+, 1mA of Ar9+, etc.) have been produced. In addition, we have started the development of high intensity uranium beams. For example, 200eμA of U33+ and U34+ have been produced so far. In respect to high charge state ions, 1eμA of Ar18+, 133eμA of Ar16+, and 4.9eμA of U47+ have been measured. In addition, ion beam profile measurements are presented with, and without the sextupole magnetic field energized. These experimental results are being compared with simulations using the WARP code.
2007, 31(S1): 8-12.
Abstract:
A Superconducting ECR ion source with Advanced design in Lanzhou (SECRAL) was successfully built to produce intense beams of highly charged ions for Heavy Ion Research Facility in Lanzhou (HIRFL). The ion source has been optimized to be operated at 28GHz for its maximum performance. The superconducting magnet confinement configuration of the ion source consists of three axial solenoid coils and six sextupole coils with a cold iron structure as field booster and clamping. For 28GHz operation, the magnet assembly can produce peak mirror fields on axis 3.6T at injection, 2.2T at extraction and a radial sextupole field of 2.0T at plasma chamber wall. A unique feature of SECRAL is that the three axial solenoid coils are located inside of the sextupole bore in order to reduce the interaction forces between the sextupole coils and the solenoid coils. During the ongoing commissioning phase at 18GHz with a stainless steel chamber, tests with various gases and some metals have been conducted with microwave power less than 3.2kW and it turned out the performance is very promising. Some record ion beam intensities have been produced, for instance, 810eμA of O7+, 505eμA of Xe20+, 306eμA of Xe27+, 21eμA of Xe34+, 2.4eμA of Xe38+ and so on. To reach better results for highly charged ion beams, further modifications such as an aluminium chamber with better cooling, higher microwave power and a movable extraction system will be done, and also emittance measurements are being prepared.
2007, 31(S1): 13-17.
Abstract:
The design of each component of the Multipurpose Superconducting ECR Ion Source (MS-ECRIS) has been completed and some items are ready. The magnets and the cryostat are under construction at ACCEL and the commissioning is scheduled for March 2007. The mechanical have been optimized and their construction is under way; the microwave system is under refurbishment and the 65kV power supply is available and upgraded for afterglow operations. Pumping and extraction system were adapted to the EIS testbench of GSI Darmstadt. The description of each part will be given in the paper along with a schedule of the forthcoming development and experiments.
2007, 31(S1): 18-22.
Abstract:
Since the last ECR Workshop, NSCL/MSU has been involved in a vigorous ECR ion source R&D program, which resulted in the construction of an off-line test ECR ion source (ARTEMIS-B) for new beam development and ion optics studies. Also the design and partial completion of a 3rd generation, fully superconducting ECR ion source, SuSI has been accomplished. This paper is an overview of the construction projects and the different R&D activities performed with the existing ion sources. These activities include development of metallic ion beam production methods using evaporation with resistive and inductive ovens and sputtering of very refractory metals. Ion optics developments include testing different focusing elements (magnetic solenoid lens, electrostatic quadrupole triplet lens, Einzel lens, electrostatic double doublet quadrupole combined with an octupole lens), and different beam forming and diagnostics devices. The detailed results will be presented at the workshop in separate talks and posters.
2007, 31(S1): 23-26.
Abstract:
A new compact version of the "liquid He-free" superconducting Electron Cyclotron Resonance Ion Source, to be used as an injector for the U-400M cyclotron, is presently under construction at the FLNR in collaboration with LHE (JINR). The axial magnetic field of the source is created by the superconducting magnet, and the NdFeB hexapole is used for the radial plasma confinement. The microwave frequency of 14GHz will be used for ECR plasma heating. The DECRIS-SC2 superconducting magnet is designed for the induction of a magnetic field on the axis of the source of up to 1.4T (extraction side) and 1.9T (injection side) at nominal current of 75A. Cooling of the coils is carried out by GM cryocooler with cooling power of 1W at the temperature 4.5K. The basic design features of the superconducting magnet and of the ion source are presented. The main parts of the source are in production. The first beam test of the source is expected in the beginning of 2007.
2007, 31(S1): 27-30.
Abstract:
Superconducting magnets are widely used in ECR ion sources. The intensity and form of the magnetic field plays an important role in the way towards higher performance sources. During the development steps, the design principles and geometries had to be adapted to reach higher fields using state-of-the-art technologies and design tools. Production, assembly, and tests of these superconducting magnets are presented and a short outlook on possible future developments is given.
2007, 31(S1): 31-36.
Abstract:
An advanced superconducting ECR ion source named SECRAL has been constructed at Institute of Modern Physics of Chinese Academy of Sciences, whose superconducting magnet assembly consists of three axial solenoid coils and six sextupole coils with a cold iron structure as field booster and clamp. In order to investigate the structure of sextupole coils and to increase the structural reliabilities of the magnet system, global and local structural analysis have been performed in various operation scenarios. Winding pack and support structure design of magnet system, mechanical calculation and stress analysis are given in this paper. From the analysis results, it has been found that the magnet system is safe in the referential operation scenarios and the configuration of the magnet complies with design requirements of the SECRAL.
2007, 31(S1): 37-40.
Abstract:
Superconducting magnet system for a 28GHz ECR ion source has been designed. The maximum axial magnetic fields are 4T at the rf injection side and 2T at the beam extraction side, respectively. The hexapole magnetic field is about 2T on the inner surface of the plasma chamber. The superconducting coils consist of six solenoids and six racetrack windings for a hexapole field. Two kinds of coil arrangements were investigated: one is an arrangement in which the hexpole coil is located in the bore of the solenoids, and another is the reverse of it. The coils use NbTi-Copper conductor and are bath-cooled in liquid helium. The six solenoids are excited with individual power supplies to search for the optimal axial field distribution. The current leads use high Tc material and the cryogenic system is operated in LHe re-condensation mode using small refrigerators. The thermal insulated supports of the cold mass have also been designed based on the calculated results of the magnetic force. The heat loads to 70K and LHe stages were estimated from the design of the supports, the current leads and so on.
2007, 31(S1): 41-45.
Abstract:
Extensive plasma potential measurements have been carried out using a device developed at JYFL. In this article the main results of the measurements will be summarized. A new simulation code to study the electron heating is being developed. One objective of the code is to determine the change of the electron loss cone when the magnetic field component of the electromagnetic wave is taken into account along with the permittivity of the plasma. As a part of the work, accurate X-ray measurements have been initiated. A new plasma chamber based on the MMPS-concept (Modified MultiPole Structure) has successfully been constructed and tested with the JYFL 6.4GHz ECRIS. The results and conclusions will be presented elsewhere in these proceedings. In the same article, a new concept of ECRIS and first results will be presented. The active development work of evaporation ovens has been carried out in a joint European collaboration (ISIBHI). The objective of the task is to make the operation of the oven reliable at 2000℃ for several days. Both resistively and inductively heated ovens have been studied and further developed. The status of this work will be presented.
2007, 31(S1): 46-50.
Abstract:
In the beginning of the 90s, T. Taylor and his collaborators demonstrated ECR sources operating at low frequency (i.e. 2.45GHz) are able to produce very intense single charge light ion beams.
At CEA/Saclay, the SILHI source developments started in 1995. Since 1997 more than 100mA proton or deuteron beams are routinely produced in pulsed or continuous mode. To comply with ADS reliability constraint, important improvements have been performed to increase the installation reliability. Moreover, to optimize the beam transport in the low energy beam line, the extraction system was carefully designed and space charge compensation studies were undertaken. An important step has been reached in 2005 with the development of a permanent magnet source able to produce a total beam of 109mA at 85kV.
A new test bench named BETSI, especially dedicated to permanent magnet source developments, is presently under construction. It will allow analysing positive or negative extracted beams up to 50keV and 100mA.
In addition, for several years work has been done to optimize the production of negative hydrogen ion beam with such an ECR source. Recent analysis pushed towards the construction of a new set up based on a multicusp magnetic configuration.
After a brief overview of the CEA/Saclay source developments, this article will point out on the recent results and present status.
2007, 31(S1): 51-54.
Abstract:
The GTS-LHC ion source, designed and build by CEA Grenoble, was installed and commissioned at CERN in 2005. Since than the source has delivered oxygen and lead ion beams (O4+ and Pb27+ from the source, Pb54+ from the linac) for the commissioning of the Low Energy Ion Ring (LEIR). Results of this operation and attempts to improve the source performance and reliability, and the linac performance will be presented in this paper.
2007, 31(S1): 55-59.
Abstract:
The high charge state all permanent Electron Cyclotron Resonance Ion Source (ECRIS) LAPECR2 (Lanzhou All Permanent magnet ECR ion source No.2) has been successfully put on the 320kV HV platform at IMP and also has been connected with the successive LEBT system. This source is the largest and heaviest all permanent magnet ECRIS in the world. The maximum mirror field is 1.28T (without iron plug) and the effective plasma chamber volume is as large as O67mm×255mm. It was designed to be operated at 14.5GHz and aimed to produce medium charge state and high charge state gaseous and also metallic ion beams. The source has already successfully delivered some intense gaseous ion beams to successive experimental terminals. This paper will give a brief overview of the basic features of this permanent magnet ECRIS. Then commissioning results of this source on the platform, the design of the extraction system together with the successive LEBT system will be presented.
2007, 31(S1): 60-62.
Abstract:
Four ECR ion sources have been operated in National Institute of Radiological Sciences (NIRS). Two ECR ion sources supply various ion species for the Heavy Ion Medical Accelerator in Chiba (HIMAC). The 10GHz NIRS-ECR ion source mainly produces C2+ ions for the heavy-ion therapy. Ions of Si, Ar, Fe, Kr and Xe are usually produced by the 18GHz NIRS-HEC ion source for physical and biological experiments. The other two compact ECR ion sources with all permanent magnet configuration have been developed for the new generation carbon therapy facility. One of these, the Kei-source, is a prototype which has been installed to the NIRS-930 cyclotron for axial injection. The other source, Kei2-source, is a demonstration source and utilized for the new generation Linac. In addition, both Kei sources have been used to study fundamental properties. In this paper, present status of the ion sources and recent developments are reported.
2007, 31(S1): 63-65.
Abstract:
An ECR O+ ion source and LEBT system have been developed for the upgrade of 1MeV Integral Split Ring RFQ at Peking University. To satisfy the requirement of RFQ, a more than 10mA oxygen beam has been extracted at 22kV through a 5mm diameter aperture. Its normalized root-mean-square emmitance is less than 0.1π.mm.mrad, which is required by RFQ accelerator. The LEBT matching section is redesigned upon the bench test results. The preliminary results will be presented in this paper.
2007, 31(S1): 66-69.
Abstract:
A compact 14.5GHz electron cyclotron resonance (ECR) ion source for the production of slow, multiply charged ions has been constructed, with the plasma-confining magnetic field produced exclusively by permanent magnets. Microwave power of up to 175W in the frequency range from 12.75 to 14.5GHz is transmitted from ground potential via a PTFE window into the water-cooled plasma chamber which can be equipped with an aluminum liner. The waveguide coupling system serves also as biased electrode, and two remotely-controlled gas inlet valves connected via an insulating break permit plasma operation in the gas-mixing mode. A triode extraction system sustains ion acceleration voltages between 1kV and 10kV. The ECR ion source is fully computer-controlled and can be remotely operated from any desired location via Ethernet.
2007, 31(S1): 70-74.
Abstract:
Since 1998, many experiments for metallic ion production have been done on LECR2 (Lanzhou ECR ion source NO.2), LECR3 (Lanzhou ECR ion source NO.3) and SECRAL (Superconductiong ECR ion source Advanced design in Lanzhou) at Institute of Modern Physics. The very heavy metallic ion beams such as those of uranium were also produced by the plasma sputtering method, and supplied for HIRFL (Heavy Ion Research Facility in Lanzhou) accelerators successfully. During the test, 11.5eμAU28+, 9eμAU24+ were obtained. Some ion beams of the metal having lower melting temperature such as Ni and Mg ion beams were produced by oven method on LECR3 too. The consumption rate was controlled to be lower for 26Mg ion beams production, and the minimum consumption was about 0.3mg per hour. In this paper, the main experimental results are given. Some discussions are made for some experimental phenomena and results, and some conclusions are drawn.
2007, 31(S1): 75-79.
Abstract:
A radial sputter probe has been developed for the AECR-U as an additional method of producing metal ion beams. Negative voltage is applied to the probe to incite collisions with target atoms, thereby sputtering material into the plasma. The sputter probe is positioned through one of the 6 radial access slots between the permanent hexapole structure of the AECR-U. The probe position can be varied with respect to the inner edge of the hexapole magnet structure. Charge state distributions and peak beam intensities at bias voltages up to －5kV were obtained for gold samples at varying distances of the probe with respect to the plasma. For high charge states production the radial position with respect to the plasma was more sensitive than for the medium and lower charge states. For high charge state ion production the probe was optimized at a distance of 0.6cm inside the chamber wall (4.1cm from the center of the chamber). Stable beams with peak intensities of up to 28eμA of Au24+ and 1.42eμA of Au41+ have been produced using the sputter probe technique.
In addition, a solid state circuit under development by Scientific Solutions, Inc which provides a bandwidth up to 100MHz was used to drive the 14GHz klystron amplifier for the LBNL AECR-U ion source. Various broadband and discrete heating modes were tested and the results for high charge state ion production were compared with single frequency heating.
2007, 31(S1): 80-84.
Abstract:
Experimental studies were conducted to characterize and improve the performance of the flat-B ECR ion source. The emittance of the source was investigated for the first time. The output beam currents of high-charge-states of Ar (q>8) were nearly doubled by increasing the plasma electrode aperture from 4mm to 6mm in diameter. To investigate possible enhancements with broadband microwave radiation, a "white" Gaussian noise generator was employed with a TWT amplifier to generate microwave radiation with a bandwidth of ～200MHz. The performance of the flat-B ECR ion source was found to be much better with narrow bandwidth radiation when the source was operated in the flat-B region. However, the ion beam intensities and charge state distributions were improved with the broadband radiation when the source was tuned {off} the flat-B region.
2007, 31(S1): 85-89.
Abstract:
Previous experiments with organo-metallic compounds like ferrocene, nickelocene and magnesocene showed that a pure spectrum must be obtained on the residual gas mass analyser before running successfully on the ion source. In collaboration with the chemistry department of the University of Caen, LCMT-ENSI Caen, the synthesis of these metallocene compounds has been studied to provide enriched isotopic compounds to GANIL's users. The chemical transformation yields were 90%, 80% and 43%, respectively.Vanadocene, chromocene, colbatocene and ruthenocene compounds have first been studied with a gas mass analyser and then successfully tested on the ECR 4M ion source at GANIL. Some 15eμA of 51V11+, 20eμA of 52Cr11+, 22eμA of 59Co11+, and 17eμA of 102Ru11+ were achieved. The comparison between the results obtained on the gas mass analyser and the ion beams provided by the source has allowed us to validate this method of determining whether or not an organo-metallic compound could be a candidate for running on our ECR ion source. As the ECR ion sources are tuned and used alternately on the GANIL injectors, the available time for the tests is rare, so this method could be an alternative for the validation of new compounds.
2007, 31(S1): 90-93.
Abstract:
In this paper the first results of the new ECR source at the KVI are presented. The source has been built following the design of Jyvaskyla University, which is based on the AECR-U of LBNL. As the commissioning is going on, it seems that the extraction and analysing systems inherited from the old source are the limiting factors for the performance of the new source. Beam currents achieved with the source are at the moment a factor of 3 lower than the AECR source used at the Jyvaskyla University. Further modifications to improve the source performance will be discussed.
2007, 31(S1): 94-96.
Abstract:
With the prototype ECR ion source for the next carbon therapy facility in Japan a new series of measurements has been performed in order (a) to find the highest beam currents of C4+ ions, and (b) to study the effect of "special" gas- mixing by using a chemical compound as a feed gas. An isotopic effect has been found in a previous experiment: with deuterated methane (CD4 gas) the C5+ beam currents are about 10% higher than with regular methane (CH4 gas). For butane gases (C4D10 and C4H10 respectively) the isotopic effect for C5+ production is even stronger (>15%). For production of C4+ ions the isotopic effect appears to be absent. It turns out that the relative amount of carbon is much more important: acetylene gives 15% higher C4+ current than butane, which in turn gives about 10% higher C4+ ion currents than methane.
2007, 31(S1): 97-100.
Abstract:
At RIKEN, three ECR ion sources (10GHz ECRIS, 18GHz ECRIS and liquid He-free SC-ECRIS) are operated as external ion sources of heavy ion accelerators. In the last year, multi-charged uranium ion beam was produced from 18GHz ECRIS by using UF6 and the 238U ion was successfully accelerated by the accelerator complex which consists of the RFQ linear accelerator, RIKEN heavy ion linear accelerator (RILAC) and RIKEN ring cyclotron accelerator (RRC). The typical beam intensity of 238U14+ was about 2pμA on faraday cup after analysing magnet. 70Zn beam was still supplied for the new super-heavy element search experiment with insertion method. Intense beam of 70Zn16+ was produced for long term (～43 days) without vacuum break and remarkably low material consumption rate (～100μgr/h). We already supplied Zn beam longer than 200 days for this experiment. 48Ca ion was also produced by insertion method using 48CaO rod for the nuclear physics experiment. In this contribution, we will present ion source parameter and techniques for production of each of the metal ions.
2007, 31(S1): 101-104.
Abstract:
Development work with solid materials at the Argonne National Laboratory ECR ion sources has been focused on two areas - introduction of materials with low vapour pressures, and increasing the beam intensities of heavy beams (i.e. - lead and uranium). An induction oven, with a demonstrated operating temperature extending to 2000℃, has been utilized to produce a Ti-50 beam with an intensity of 5.5eμA (12+). In addition, a refinement of the sputter technique has been employed which has resulted in a 42% improvement in lead beam intensities. Details of the induction oven as well as the refined sputter technique will be presented.
2007, 31(S1): 105-107.
Abstract:
A new plasma chamber for the Texas A&M 14.5GHz ECR ion source ECR2 has been recently installed and the beam analysis line has been recently upgraded with the replacement of the solenoid with a shorter Glaser lens. The source is now used along with the 6.4GHz ECR1 for injection of beams into the K500 cyclotron. The new plasma chamber incorporates water-carrying copper tubes, each with an inner diameter of 0.7mm and an outer diameter of 1.8mm, interposed between the NbFeB permanent magnets and the aluminum plasma-chamber wall. The design allows for a much higher water flow and thus better cooling than the previous design, which used a thin, water-cooled liner. The source commissioning and operation is described.
2007, 31(S1): 108-110.
Abstract:
The ECR ion source DECRIS-4 has been designed and constructed at the FLNR JINR to be used as a second injector of heavy multiply charged ions for the U-400 cyclotron. The design of the magnetic structure of the source was based on the idea of the so-called "magnetic plateau". The axial magnetic field is formed by three independent solenoids enclosed in separated iron yokes. As a result the superposition of the coils and hexapole magnetic fields creates the enlarged resonance volume. The first experiments showed that the source was able to produce more than 300eμA of Ar8+ when only 100W of microwave power was used. During the last experiment almost 500eμA of Ar8+ was extracted with the same power. In this paper we will present the preliminary results with other gaseous ions, such as oxygen, krypton and xenon.
2007, 31(S1): 111-114.
Abstract:
The concept for a 2 charge state injector for a "RIA type" accelerator has been presented. Progress toward an operational prototype 2Q-LEBT system at Argonne National Laboratory (ANL) is under way. The existing BIE 100 all permanent magnet ECR has been placed on a high voltage platform capable of a combined >100kV with q/m separation at ground level. Remote control of the devices on the platform has been implemented. Other components of the facility are currently being tested. The components of an achromatic bending system are currently being procured. This paper will present recent work at the facility as well as preliminary development of solid materials using the BIE 100.
2007, 31(S1): 115-117.
Abstract:
The Lanzhou All Permanent magnet ECR ion source NO.1 (LAPECR1) is the first all permanent magnet multiple ECRIS made in IMP. This ECRIS is running at 14.5GHz and can provide intense low charge state ion beams (varying from several to hundreds of eμA) or medium charge state ion beams (varying from several to tens of eμA). The size of source body is O102mm×296mm, the compactness and economical features enable the source suitable to be put on a HV platform or equipped by a small laboratory. This article gives the main parameters of the ion source.
2007, 31(S1): 118-122.
Abstract:
The Latest developed LECR2M (Lanzhou ECR No. 2 Modified) source is the updated one of LECR2 (Lanzhou ECR No. 2) source at IMP. It has been assembled on the low energy ion beam experimental platform to produce MCI beams for atomic physics and material physics experimental research. In our updating program, the structure of injection and extraction components has been modified to make the source structure more simple and effective. The hexapole magnet has also been replaced by a new hexapole magnet with higher radial field and larger inner diameter. With this updating, stronger magnetic field confinement of the ECR plasma is possible and better base vacuum condition is also achieved. LECR2M was designed to be operated at 14.5GHz. During the preliminary test, 1.3emA O6+ beam was extracted with the injected rf power of 1.1kW. The source has been used to deliver intense MCI beams for different experiments. After some discussion of the main features of this newly updated source, some of the typical commissioning test results of LECR2M will be presented.
2007, 31(S1): 123-127.
Abstract:
As they are first optimized for their ion losses, ECRISs are always under a fundamental compromise: having high losses and strong confinement at the same time. To help ECR ion source developers in the design or improvement of existing machines, general comments are presented in a review article being soon published. In this 160 pages contribution, fundamental aspects of ECRISs are presented, with a discussion of electron temperature and confinement and ion confinement. Then, as microwaves play a key role in these machines, a chapter presents major guidelines for microwave launching and coupling to ECR plasma. Moreover, once ECR plasma is created, understanding this plasma is important in ion sourcery; and a section is dedicated to plasma diagnostics with an emphasis on the determination of electron and ion density and temperature by vacuum ultraviolet (VUV) spectroscopy. Another chapter deals with the role of magnetic confinement and presents updated scaling laws. Next chapter presents different types of ECRISs designed according to the main parameters previously described. Finally, some industrial applications of ECRISs and ECR plasmas in general are presented like ion implantation and photon lithography. Some hints taken from this review article are presented in the following article.
2007, 31(S1): 128-132.
Abstract:
As clearly demonstrated at several laboratories, the performances of electron-cyclotron resonance (ECR) ion sources can be enhanced by increasing the physical sizes (volumes) of embedded ECR zones. Enlarged ECR zones have been achieved by engineering the central magnetic field region of these sources so they are uniformly-distributed "volumes" in resonance with single-frequency rf power. Alternatively, the number of ECR {surfaces} in conventional minimum-B geometry sources can be increased by heating their plasmas with multiple, discrete frequency microwave radiation. Broadband rf power offers a simple, low cost and arguably more effective means for increasing the physical sizes of the ECR zones within the latter source type. In this article, theoretical arguments are made in support of the volume effect and the charge-state enhancing effects of broadband microwave radiation (bandwidth: 200MHz) plasma heating are demonstrated by comparing the high-charge-states of Ar ion beams, produced by powering a conventional minimum-B geometry, 6.4GHz ECR ion source, equipped with a biased disk, with those produced by conventional bandwidth (bandwidth: ～1.5MHz) radiation.
2007, 31(S1): 133-136.
Abstract:
We measured the main plasma parameters (density of electron, temperature of electron and ion confinement time) and beam intensity of various heavy ions as a function of Bmin. The Bmin strongly affects the field gradient at the resonance zone, consequently the plasma parameters and beam intensity are changed. Based on these experimental results, we started to construct new 18GHz ECRIS and make a detailed design of the 28GHz SC-ECRIS for RIKEN RI beam factory project.
2007, 31(S1): 137-141.
Abstract:
Since the end of '70s the Electron Cyclotron Resonance ion sources (ECRIS) allowed to increase both the energy and intensity of the beams available from different types of accelerators; perspectives for the future are still optimistic. It is commonly agreed that only some ECRIS parameters have been fully exploited, whether some others are still not efficiently used, or not understood. The developments in the last 20 years have followed the so called Standard Model and the availability of higher frequency generators and higher field magnets have permitted relevant increase; the use of Nb3Sn may extend the range. The availability of new schemes of microwave coupling to plasma is promising, and the focusing of the electromagnetic wave towards the chamber axis may improve the density of warm electron population. The paper will also describe some critical point of the 3rd generation ECRIS (including technological troubles and limits) and the scenario for future 4th generation ECRIS, operating at f=56—75GHz, to be built in 2010s.
2007, 31(S1): 142-146.
Abstract:
Experiments have shown that especially the radial magnetic field component plays a crucial role in the production of highly charged ions with Electron Cyclotron Resonance Ion Sources (ECRIS). However, in several room temperature operating ECRISs the radial magnetic field strength is below the optimum value, mainly due to the limits in permanent magnet technology. Remarkable radial magnetic field improvement can be reached with a relatively simple and cost-effective idea called Modified MultiPole Structure (MMPS). The MMPS differs strongly from the former structures because here the magnetic field is increased only locally without affecting the plasma size. The idea was studied experimentally with a new MMPS plasma chamber prototype, which was designed and constructed for the JYFL 6.4GHz ECRIS. The new chamber is versatile and made it possible to perform several new types of measurements. These showed that the MMPS is especially applicable to increase very high charge-state ion production. Typically the ion current increases more than a factor of 2 in the case of highly charged ions such as Ar16+.
2007, 31(S1): 147-151.
Abstract:
The coupling between microwave generators and ECR ion sources (ECRIS) is a key point for the design of the new generation ECRIS as well as for the optimization of the existing ones. The electromagnetic characterization of the plasma chamber where the ionization phenomena take place is a fundamental starting point to understand and model such process. In such effort the complex structures of the injection and extraction flanges together with the large dimensions of the chamber and the high frequencies that are typically used make impossible an analytical solution and also create great difficulties in the modelling even with state-of-art electromagnetic simulators (CST, HFSS). In the following paper the results of some numerical calculations for the optimum plasma chamber excitation will be presented along with the experimental measurements carried out with the SERSE ion source at INFN-LNS. A campaign of measurements is also planned to further investigate the microwave coupling and the mode excitation, which determines the efficiency of the ECR plasma heating.
2007, 31(S1): 152-155.
Abstract:
A Simple Mirror Ion Source with 75GHz pumping (SMIS 75) has been created. The confinement system is a mirror trap with magnetic field in the plug up to 5T, variable length 15—20cm and mirror ratio 3—5. Plasma heating is performed by the microwave radiation of a gyrotron (frequency 75GHz, power up to 200kW, pulse duration up to 150μs). The first results on plasma creation, heating and confinement are presented. Gas discharge conditions and charge state distributions are investigated. The main features of the plasma are high density and short confinement time. Plasma is confined in the trap in quasi-gas-dynamic regime. This means very short rising time and very dense plasma flux.
2007, 31(S1): 156-158.
Abstract:
In order to extend the capabilities of the ATOMKI-ECRIS it is being transformed into a modified plasma device by changing its three main components with new ones. The cylindrical plasma chamber is replaced by a larger one (ID=10cm, L=40cm). A new NdFeB multi-pole radial trap was designed and purchased. The basic configuration is 6-pole, but 8- or 12-pole arrangements can also be formed later. The present microwave source (2000W, 14.5GHz) and two additional low-power, wide frequency TWT amplifiers give many opportunities to form plasmas with different sizes and characters. Actually a new facility with two sharply different operation modes is being established. All the modifications are reversible so the transformation of the ECRIS into this new device or back can be easily done.
2007, 31(S1): 159-161.
Abstract:
A Simple Mirror Ion Source with 75GHz pumping (SMIS 75) has been created. The confinement system is a mirror trap with magnetic field in the plug up to 5T, variable length 15—20cm and mirror ratio 3—5. The plasma of metal ions is injected into the trap by a special vacuum arc minigun. Plasma heating is performed by the microwave radiation of a gyrotron (the frequency of 75GHz, power up to 200kW, pulse duration up to 150μs). The results of the experiment have demonstrated substantial multiple ionization of metal ions. For a metal with high melting temperature (Pt), heating shifts the average ion charge from Pt2+ up to Pt7+. Maximum stripped observed ion is Pt10+. Total current of ion beam is about 300mA.
2007, 31(S1): 162-164.
Abstract:
The question posed in the title concerns the explanation of a well-practised technique in ECR ion sources for increasing the output of the highest charge states of the ions of interest. For a long time the most accepted model was that of ion cooling, being a `single-particle' effect. Two recent papers, likely inspired on earlier work, are proposing a ‘collective’ effect due to non-linear plasma-wave interaction, giving rise to turbulent heating. The mixing gas will in that picture reduce the heating. A few experiments are suggested to help unravel the problem of stating which effect is dominating.
2007, 31(S1): 165-169.
Abstract:
The TrapCAD code was developed in the 90s on DOS-platform in order to visualize the magnetic field line structure of ECR and other ion sources and to simulate the movement of individual charged particles in magnetic traps. Recently the code was re-written for Windows and underlied a major upgrading. The paper shows the new features. The spatial and energy structure of the non-lost and lost electrons are studied in a more detailed way for the case of the ATOMKI-ECRIS, as example. Using the datafiles of the lost electrons, their energy distribution is calculated and compared with known X-ray (bremsstrahlung) observations.
2007, 31(S1): 170-173.
Abstract:
Earlier we reported an ion current jump which was observed at a fixed negative biased disc potential in the 6.4GHz ECR ion source at VECC, Kolkata. In a recent experiment with neon ions, we measured the time spectra of the ion current and observed the presence of a burst frequency in the kilohertz range. This frequency shows a correlated jump with the ion current jump described above. Another interesting feature is that the observed burst frequency shows a good linear correlation with the extracted ion current. The higher the ion current, the higher is the burst frequency. This means that current per burst is a constant factor; when there are more number of bursts, the current also increases.
2007, 31(S1): 174-177.
Abstract:
A theoretical and computational model is presented to study the ionization of the argon electron cyclotron resonance (ECR) microwave discharge using a quasi-three-dimensional electromagnetic particle-in-cell plus Monte Carlo collision method. The interaction between the charged particles and microwave fields are described by the electromagnetic mode of particle-in-cell method. The collision processes are treated with Monte Carlo method. The simulation code is the original work. The results of the particle simulation for the ECR discharge of argon gas which include the microscopic features of charged particles and the electromagnetic characteristics of the ECR discharge plasma, and also the transient phenomena have been presented.
2007, 31(S1): 178-181.
Abstract:
The axial emitted bremsstrahlung spectra were measured on SECRAL (Superconducting ECR ion source with Advanced design in Lanzhou) using an HPGe detector. The spectral temperature Tspe was obtained from the linear fit of the spectra in the semi-log present. The evolution of Tspe with microwave power and magnetic field configuration is investigated in this paper.
2007, 31(S1): 182-186.
Abstract:
The transverse emittance of an ion beam describes its transverse size as the particles are transported from a source to a target. It allows for predicting beam losses in limiting apertures and the beam focus size at the target. Various definitions and issues are discussed. The most common and emerging measuring techniques are presented, including their advantages. Several methods of emittance data analysis, their accuracy and trustworthiness, are discussed.
2007, 31(S1): 187-191.
Abstract:
This paper reviews recent experimental work done with the off line source ARTEMIS-B at the NSCL. This source was built during the year 2005 and provides opportunities for off line development that can benefit the Coupled Cyclotron Facility (CCF) operation while minimizing the time taken away from the nuclear experimental program. The Artemis-B setup includes many beam diagnostics and a detailed description of the emittance scanner (Allison) and emittance measurement method is presented. A first beam dynamics study indicates that the analysis magnet has strong field aberrations and that the beam size in the dipole must be small in order to avoid significant beam brightness degradation. A second study compares beam brightness for different focusing systems between the ECR ion source and the analyzing magnet. Two electrostatic devices: a quadrupole triplet and a double quadrupole doublet have been tested successively and compared to a magnetic focusing solenoid. The experimental results tend to indicate a better beam brightness at smaller emittance for the electrostatic devices, although emittances measured for each focusing element were for a large part dependant on the tuning procedure developed to minimize the effects of the analyzing magnet.
2007, 31(S1): 192-195.
Abstract:
An ion beam extracted from an ECRIS suffers from the inhomogeneous distribution of cold electrons within the minimum B configuration, necessary to confine the plasma. Especially for higher ion currents, the space charge force is not negligible any more, and because of the nonlinear force, emittance growth will occur.
Measurements of the profile and the emittance of the beam directly behind the source show the complicated correlation between extraction voltage and plasma density. The emittance has been measured with a pepper pot device to account for the inhomogeneous azimuthal distribution of the beam. These results indicate that further information about the profile is required. To visualize the beam profile a tantalum foil with a thickness of 20μm has been used for an electrical beam power between 10 and 50W. Looking on the back side of the foil with a CCD camera it is possible to record the profile in real time. As a more sensitive diagnostic tool viewing targets made from BaF has been used.
Three dimensional computer simulations have been used to identify the reason for the structures, observed in measurements.
2007, 31(S1): 196-200.
Abstract:
The Coupled Cyclotron Facility (CCF) has been operating at the NSCL since 2001, providing up to 160MeV/u heavy ion beams for nuclear physics experiments. Recent steps, particularly the improvement of the ECR-to-K500 injection line, were taken to improve the CCF performance. For that purpose an off-line ECR source, ARTEMIS-B, was built and used to investigate the impact on beam brightness under various source operating conditions, different initial focusing systems and current analysis dipole. Beam dynamics simulations including space-charge and 3D electrostatic field effects were performed and beam diagnostics including emittance scanner were used, leading to a better understanding of the CCF beam injection process. New initial electrostatic focusing elements such as a large-bore quadrupole triplet and a quadrupole double-doublet with compensating octupole were tested, and a new beam tuning procedure was established to improve the beam brightness for the CCF. Following these efforts, a significant increase of primary beam power out of the CCF has been achieved.
2007, 31(S1): 201-205.
Abstract:
The problem of extracting space-charge-limited ion beams from spherical emission boundaries is analyzed for simple, two electrode, parallel-plate and spherical sector electrode systems by application of Langmuir-Blodgett theory with account taken for the divergent lens effect caused by the aperture in the extraction electrode. Results derived from simulation studies for the three electrode system, designed for use with the Oak Ridge National Laboratory ECR ion source, complement predictions made from elementary analytical theory with or without magnetic field in the extraction region of the source. Under minimum half-angular divergence (minimum emittance) conditions, the plasma emission boundary has an optimum curvature and the perveance, P, (i.e, current density, j+ and extraction gap, d), has an optimum value for a given charge-state. From these studies, we find that the optimum perveance for any electrode system can be determined from the Child-Langmuir relation for the parallel-plate electrode system multiplied by a factor, F with value 0.49≤F≤1.
2007, 31(S1): 206-210.
Abstract:
ECRIS's dedicated to radioactive ion production must be as efficient as those used for production of stable elements, but in addition they are subject to more specific constraints such as radiation hardness, short atom-to-ion transformation time, beam purity and low cost. Up to now, different target/ion-source systems (TISSs) have been designed, using singly-charged ECRISs, multi-charged ion sources or an association of singly-to-multi-charged ECRISs. The main goals, constraints and advantages of different existing ECR setups will be compared before a more detailed description is given of the one designed for the SPIRAL II project and its future improvements.
2007, 31(S1): 211-215.
Abstract:
An ECR ion source for charge breeding of radioactive ions from the ISAC facility at TRIUMF has been set up at a test stand. It has been operated with different ion sources for the injection of singly charged ions and the efficiency, breeding time and emittance have been determined for several elements. A maximum efficiency of more than 6% for the breeding of Kr12+ has been achieved so far. Additionally the charge exchange of Rb and Cs ions in the range of 10+ to 23+ with residual gas molecules in the transport beam lines has been investigated. The absolute values for the cross sections at 10—15 q keV agree with predictions extrapolated from lower charge states but the strong dependence on the ionization energy of the gas molecules could not be verified.
2007, 31(S1): 216-218.
Abstract:
At ISOLDE (CERN), an on-line test bench is dedicated to charge breeding experiments with a 14GHz Phoenix ion source, for the investigation of the 1+→n+ scenario at next generation ISOL-type facilities. This year, various technical developments have been undertaken for intensifying the tests of the on-line performances of the booster with a high diversity of stable and radioactive ion beams. This contribution will present an overview of the latest developments, the current challenges, and some perspectives for the future use of the Phoenix booster for physics experiments at ISOLDE.
2007, 31(S1): 219-222.
Abstract:
A new radioactive beam facility for ATLAS, the Californium Rare Ion Breeder Upgrade (CARIBU), is under construction. The facility will use fission fragments from a 1 Ci 252Cf source; thermalized and collected into a low-energy beam by a helium gas catcher. In order to reaccelerate these beams, the existing ATLAS ECR-I ion source is being redesigned to function as a charge breeder source. The design and features of this charge breeder configuration is discussed and the project status described.
2007, 31(S1): 223-225.
Abstract:
At the moment, a 70MeV cyclotron is under construction by the IBA company. This cyclotron will be able to accelerate H beam from a multicusp source and with a beam intensity in the range of 10mA at the source extraction. A He1+2+ beam is also required. This beam will be produced by a PANTECHNIK ECR ion source (SUPERNANOGAN) with an extracted current of 1 to 2mA. In this paper the studies and design of the two sources with a common axial injection in the cyclotron are described.
2007, 31(S1): 226-228.
Abstract:
A compact proton beam source for space simulation has been developed. A compact structure was designed in order to meet the special requirements of miniaturization. Some particular means have been adopted for improving the proton portion and beam transmission at a long distance. The experimental results showed that 8mA/30keV proton beam can be successfully obtained from this source at about 700W input microwave power.
2007, 31(S1): 229-231.
Abstract:
The high power EUV source is one of key issues in the development of EUV lithography which is considered to be the most promising technology among the next generation lithography. However neither DPP nor LPP seems to meet the requirements of the commercial high-volume product. Insufficiency of DPP and LPP motivate the investigation of other means to produce the EUV radiation required in lithography. ECR plasma seems to be one of the alternatives. In order to investigate the feasibility of ECR plasma as a EUV light source, the EUV power emitted by SECRAL was measured. A EUV power of 1.03W in 4$\uppi$ sr solid angle was obtained when 2000W 18GHz rf power was launched, and the corresponding CE was 0.5%. Considering that SECRAL is designed to produce very high charge state ions, this very preliminary result is inspiring. Room-temperature ECR plasma and Sn plasma are both in the planned schedule.
2007, 31(S1): 232-235.
Abstract:
A 2.45GHz microwave-driven ion source is being used to provide 40mA of deuterium ion beam (peak current) for an RFQ accelerator as part of a neutron source system. We have also designed a 60kV electrostatic LEBT using computer simulations. In our experiment, we measured the hydrogen and deuterium ion beam currents as functions of discharge power, gas flow, and magnetic field strength. The required beam current was obtained using less than 700W of net microwave power with a gas flow of less than 1.5sccm. From the rise time data, it was determined that in order to obtain a high percentage of atomic ions in the beam, the beam extraction should start after 1ms of switching on the microwave power. At steady state, the proton fraction was above 90%.
2007, 31(S1): 236-236.
Abstract:
The ECR ion sources have mainly been used until now for injection of cyclotrons and a large number of these sources are presently in operation through the world. Most cyclotrons are used today for nuclear physics researches but an increasing number of these accelerators are now devoted to medical applications. The ECR ion sources have also been extensively used for producing low energy beams for academic researches in atomic and surface physics. These studies led to very encouraging results opening the way to industrial applications. In this talk some of the most promising applications of HCI beams will be reviewed. The development of these applications will require some important improvements of the ECR sources which will be discussed. A special emphasis will be given to the respective roles of ECR and EBIS ion sources in these industrial applications, and some economic and market considerations discussed.
2007, 31(S1): 237-237.
Abstract:
To go beyond the present and planned third generation ECR ion sources operating at microwave frequencies between 20 and 30GHz to a fourth generation of sources operating above 50GHz offers new opportunities and challenges. Based on the experimentally demonstrated frequency scaling, a doubling in operating frequency could provide more intense high charge state beams with higher charge states. The technical challenges include the development of magnetic structures capable of producing 8T solenoid field and 4T sextupole fields, production and coupling of high power microwave power to heat the plasma, extraction of intense multiple charge ion beams from a region of strong magnetic field and shielding of bremstrahlung from the hot electrons. In this paper, the status of high field superconducting magnets now under development for accelerator applications, gyrotrons for microwave power and other technical aspects that would be incorporated into a fourth generation ECR ion source are explored and applied to a conceptual design.
2007, 31(S1): 238-238.
Abstract:
A new type of pulse sources of multicharged ions, namely, a quasi-gasdynamic ECR source is propose. Its main difference from the classical ECR ion sources is a different, quasi-gasdynamic regime of plasma confinement in a magnetic trap. A zero-dimensional model was constructed that describes gas breakdown, formation of charge state distribution in a plasma, and plasma flux through the plugs of the trap. A wide spectrum of model experimental studies was covered. Plasma was produced and heated by a pulse (1ms) gyrotron at the frequency of 37.5GHz and power of 100kW in a cusp magnetic trap with magnetic field in plugs up to 2.5T. Such a trap has axisymmetric configuration and allows one to realize a quasi-gasdynamic regime of confinement with reliable stabilization of MHD perturbations. It was demonstrated that with such a confinement regime it is possible to generate multicharged ions and create intense (more than 1A/cm2) ion fluxes through the trap plugs. Comparison of results of calculations and data of experiments shows that they are in a good agreement, which allows us to predict with a high degree of certainty creation of an ECR source of a new generation.
The data obtained were used to design a pulse quasi-gasdynamic ECR ion source with pumping at the frequency of 100GHz, effective trap size 1m, average ion charge in plasma comparable with that in the best classical MCI ECR sources but with an order of magnitude higher flux density and absolute magnitude of plasma flux through trap plugs. Creation of intense plasma fluxes allows one to extract high-current MCI beams of high brightness. Transverse homogeneity of a plasma flux makes it possible to use multi-aperture extraction system for formation on broad intense MCI beams.
2007, 31(S1): 239-239.
Abstract:
Production of metallic ion beams in support of the experimental program at the Coupled Cyclotron Facility at the NSCL required the development of ion sputtering feed of metallic molybdenum, nickel, uranium, and zirconium for use with the ARTEMIS ion source. The production of high intensity lower to medium charge state ions required high material consumption, posing some significant difficulties in reliable long term beam stability. Resultant and ongoing hardware and technique developments to resolve these difficulties will be presented in this poster along with interesting effects of the ion source solenoid field polarity on the sputtering process.