第四代ECR离子源的主要概念(摘要)

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 oppor- tunities 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 chal- lenges 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 mul- tiple 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 acceler- ator 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.     

NSCL溅射金属离子产生研究进展(摘要)

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.     

Charge state distribution analysis of Al and Pb ions from thelaser ion source at IMP

A prototype laser ion source that could demonstrate the possibility of producing intense pulsed high charge state ion beams has been established with a commercial Nd:YAG laser (E_max=3 J,1064 nm,8-10 ns) to produce laser plasma for the research of Laser Ion Source (LIS). At the laser ion source test bench,high purity (99.998%) aluminum and lead targets have been tested for laser plasma experiment. An Electrostatic Ion Analyzer (EIA) and Electron Multiply Tube (EMT) detector were used to analyze the charge state and energy distribution of the ions produced by the laser ion source. The maximum charge states of Al¹²⁺ and Pb⁷⁺ were achieved. The results will be presented and discussed in this paper.     

VENUS离子源的最新结果(28GHz)

The nest 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 intesities. The VENUS project is focused on two main objectives. First, for the 88-Inch Cyclotron,VENUS will serve as the third injector soures boosting both the energy and itensity of beams available form the facility.Seconly,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 Xe 20 or 250eμA of U28 to 34 . These high intensity ion beam requerements present a challenge for the beam transport system since the total currents extracte from the ECR ion source reach several mA. Therefore in parallel to io beam develoments,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 ransprot form 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 ofO6 ,600eμA of Ar9 ,etc.) have been produced. In addition, we have started the developent of high intensity uranium beams. For example, 200eμA of U33 and U34 have been produced so far. In respect to high charge state ions,leμA of Ar18 ,133eμA of Ar16 ,and 4.9eμA of U47 have been measured. In addition,ion beam profile meaurements are presented with ,and without the sextupole magnetic field energized. These expeerimental results are being compared with simulations using the WARP code.     

LAPECR2离子源在320kV高压平台上的试运行

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 (?)67mm×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.     

6.4 GHz ECR ion source at VECC

The 6.4 GHz ECR ion source that was indigenously developed a few years ago has been operating continuously for injecting oxygen and neon beams to the cyclotron since 1997. VEC-ECR is a single stage high magnetic field ion source provided with a negatively biased electron repeller placed on the axis, near the injection mirror point. The supply of cold electrons and use of low mass mixing gas improve the stability of ECR plasma. Very recently, the effect of aluminum oxide coating on the copper plasma chamber wall has been studied. The plasma chamber wall was coated with aluminum by vacuum evaporation method and then exposed to oxygen gas to form aluminum oxide. It was noticed that the process substantially shifts the charge state distribution to the higher charge state with an enhancement of ion current by an order of magnitude. With the aluminized plasma chamber, the VEC-ECR can now produce 12 μA of O⁷⁺, 6.5 μA of Ar¹²⁺, 1.5 μA of Kr²⁰⁺ and 1.0 μA of Xe³¹⁺.     

Charge state distribution analysis of AI and Pb ions from the laser ion source at IMP

A prototype laser ion source that could demonstrate the possibility of producing intense pulsed high charge state ion beams has been established with a commercial Nd：YAG laser （E =3 J, 1064 rim, ~ 10 ns） to produce laser plasma for the research of Laser Ion Source （LIS）. At the laser ion source test bench, high purity （99.998%） aluminum and lead targets have been tested for laser plasma experiment. An Electrostatic Ion Analyzer （EIA） and Electron Multiply Tube （EMT） detector were used to analyze the charge state and energy distribution of the ions produced by the laser ion source. The maximum charge states of A112＋ and Pb7＋ were achieved. The results will be presented and discussed in this paper.     

多电荷态气脉冲式ECR离子源(摘要)

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/cm~2)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 lm,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.     

微波技术对ECR离子源性能的影响

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.     

超导ECR离子源DECRIS-SC2

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 CM 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.     

高电荷态ECR离子源的金属离子产生

简单介绍了采用炉子加热、 挥发性金属化合物和溅射产生ECR离子源的金属离子的3种方法和实验结果, 主要研究了铜、 锌、 镍和铁等多种电荷态离子的产生．　对3种方法分别进行了探讨．To satisfy the requirements of HIRFL (Heavy Ion Research Facility in Lanzhou), series of experiments have been done to produce metallic ion beams. By now, numerous methods have been tested, in which MIVOC (Metallic Ion from Volatile Compounds), heating oven methods and plasma sputter methods are all included. According to the experiments, the results of using MIVOC methods and heating oven methods are very good. In most of our researches, emphasis was put upon the ion production of iron, Nickel, Tantanum, copper of different charge states. Among the ion beams we have obtained, 210 μA Fe11+, 175 μA Fe12+, 142 μA Fe13+, 25 μA Fe16+, 64 μA Ni10+, 57 μA Ni13+, 31 μA Ni15+ and 15 μA Ni16+ are representative results.     

高电荷态金属离子的产生实验研究

 为满足兰州重离子加速器的实验要求，在14.5GHz高电荷态ECR离子源上做了一系列产生金属离子的实验，尝试了多种方法，包括炉子加热及MIVOC（Metallic Ion form Volatile Compounds）两种方法，其中，用炉子做的结果较理想。实验主要研究了铜、锌、镍多种电荷态离子的产生，具有代表性的是39euA的¹³⁺，30euA的Zn¹³⁺和29euA的Ni¹⁰⁺。分别给出了这三种金属离子产生的多电荷态束流峰谱图，以及实验的一些其它现象及结果，并对其进行了讨论与总结。     

SECRAL在18GHz频率下产生强流高电荷态离子束的初步结果

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 O~(7 ),505eμA of Xe~(20 ),306eμA of Xe~(27 ),21eμA of Xe~(34 ),2.4eμA of Xe~(38 ) 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.     

高电荷态ECR离子源——LECR3

研制成功了一台新的高电荷态ECR离子源,该离子源主要为原子物理实验提供各种高电荷态离子束流,是基于中国科学院近代物理研究所14.5GHz高电荷态ECR离子源设计建成的,同时在该离子源中应用多种有利于提高束流强度的技术,设计时考虑到采用双频加热,试图通过试验双频加热模式来提高高电荷态离子的产额,并设计建造了一套束流聚焦分析系统,以提高电荷态分辨率和束流传输效率.     

Argonne国家实验室ECR离子源在固体材料离子束流产生方面的研究进展

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.     

Analysis of experiments on energetic ions from laser produced plasmas with reference to hot electrons and pulsation

The need for highly charged heavy ions from projected particle accelerators has recently led to a re-evaluation of the complex processes of ion production in laser generated plasmas. Possible mechanisms for the production of intense beams of high charge state ions are investigated as is the experimental evidence for these mechanisms. The hypothesis that 20 keV ions are driven by hot electrons is not supported by experimental work to date. This work, on the other hand, suggests that 30ps pulsation is the basic mechanism for the acceleration of tantalum ions up to charge state 8+ whose energy increases linearly with charge state up to 24keV. For long pulses and charge states between 8+ and 18+, it appears that there is a secondary mechanism of electron impact ionisation by plasma electrons of approximately 200 eV in the plasma in front of the target, resulting in ions whose energy of around 24 keV is independent of charge state.     

SMIS75金属离子的多重电离

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 Pt~(2 ) up to Pt~(7 ).Maximum stripped observed ion is Pt~(10 ).Total current of ion beam is about 300mA.     

75GHz ECR等离子体

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.