Production Of Heavy Ion Beams Research Articles

New development of advanced superconducting electron cyclotron resonance ion source SECRAL (invited)

Superconducting electron cyclotron resonance ion source with advance design in Lanzhou (SECRAL) is an 18-28 GHz fully superconducting electron cyclotron resonance (ECR) ion source dedicated for highly charged heavy ion beam production. SECRAL, with an innovative superconducting magnet structure of solenoid-inside-sextupole and at lower frequency and lower rf power operation, may open a new way for developing compact and reliable high performance superconducting ECR ion source. One of the recent highlights achieved at SECRAL is that some new record beam currents for very high charge states were produced by 18 GHz or 18+14.5 GHz double frequency heating, such as 1 e microA of (129)Xe(43+), 22 e microA of (209)Bi(41+), and 1.5 e microA of (209)Bi(50+). To further enhance the performance of SECRAL, a 24 GHz/7 kW gyrotron microwave generator was installed and SECRAL was tested at 24 GHz. Some promising and exciting results at 24 GHz with new record highly charged ion beam intensities were produced, such as 455 e microA of (129)Xe(27+) and 152 e microA of (129)Xe(30+), although the commissioning time was limited within 3-4 weeks and rf power only 3-4 kW. Bremsstrahlung measurements at 24 GHz show that x-ray is much stronger with higher rf frequency, higher rf power. and higher minimum mirror magnetic field (minimum B). Preliminary emittance measurements indicate that SECRAL emittance at 24 GHz is slightly higher that at 18 GHz. SECRAL has been put into routine operation at 18 GHz for heavy ion research facility in Lanzhou (HIRFL) accelerator complex since May 2007. The total operation beam time from SECRAL for HIRFL accelerator has been more than 2000 h, and (129)Xe(27+), (78)Kr(19+), (209)Bi(31+), and (58)Ni(19+) beams were delivered. All of these new developments, the latest results, and long-term operation for the accelerator have again demonstrated that SECRAL is one of the best in the performance of ECR ion source for highly charged heavy ion beam production. Finally the future development of SECRAL will be presented.

Low-velocity ion slowing down in binary ionic mixtures

We focus our attention on the low ion velocity stopping mechanisms in a multicomponent and dense target plasmas built of quasi-classical electron fluids neutralizing binary ionic mixtures such as deuterium–tritium of current fusion interest, proton-helium like iron in the solar interior or proton-helium ions considered in planetology, as well as other mixtures of fiducial concern in the heavy ion beam production of warm dense matter at Bragg peak conditions. The target plasma is taken in a multicomponent dielectric formulation à la Fried-Conte. We stress out the occurrence of projectile ion velocities (so-called critical) for which target electron slowing down equals that of the given target ion components. The corresponding multi-quadrature computations, albeit rather heavy, can be monitored analytically through a very compact code operating a PC cluster. Slowing down results are systematically scanned w.r.t. target temperature, electron density as well as ion composition.

Low velocity ion stopping in binary ionic mixtures

Attention is focused on the low ion velocity stopping mechanisms in multicomponent and dense target plasmas built of quasiclassical electron fluids neutralizing binary ionic mixtures, such as, deuterium-tritium of current fusion interest, proton-heliumlike iron in the solar interior or proton-helium ions considered in planetology, as well as other mixtures of fiducial concern in the heavy ion beam production of warm dense matter at Bragg peak conditions. The target plasma is taken in a multicomponent dielectric formulation à la Fried–Conte. The occurrence of projectile ion velocities (so-called critical) for which target electron slowing down equals that of given target ion components is also considered. The corresponding multiquadrature computations, albeit rather heavy, can be monitored analytical through a very compact code operating a PC cluster. Slowing down results are systematically scanned with respect to target temperature and electron density, as well as ion composition.

A status report of the multipurpose superconducting electron cyclotron resonance ion source (invited)

Intense heavy ion beam production with electron cyclotron resonance (ECR) ion sources is a common requirement for many of the accelerators under construction in Europe and elsewhere. An average increase of about one order of magnitude per decade in the performance of ECR ion sources was obtained up to now since the time of pioneering experiment of R. Geller at CEA, Grenoble, and this trend is not deemed to get the saturation at least in the next decade, according to the increased availability of powerful magnets and microwave generators. Electron density above 10(13) cm(-3) and very high current of multiply charged ions are expected with the use of 28 GHz microwave heating and of an adequate plasma trap, with a B-minimum shape, according to the high B mode concept [S. Gammino and G. Ciavola, Plasma Sources Sci. Technol. 5, 19 (1996)]. The MS-ECRIS ion source has been designed following this concept and its construction is underway at GSI, Darmstadt. The project is the result of the cooperation of nine European institutions with the partial funding of EU through the sixth Framework Programme. The contribution of different institutions has permitted to build in 2006-2007 each component at high level of expertise. The description of the major components will be given in the following with a view on the planning of the assembly and commissioning phase to be carried out in fall 2007. An outline of the experiments to be done with the MS-ECRIS source in the next two years will be presented.

Intense heavy ion beam production from IMP LECR3 and construction progress of a superconducting ECR ion source SECRAL

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

Vacuum arc ion source for heavy ion fusion

Heavy ion fusion is one approach to the problem of controlled thermonuclear power production, in which a small DT target is bombarded by an intense flux of heavy ions and compressed to fusion temperatures. There is a need in present HIF research and development for a reliable ion source for the production of heavy ion beams with low emittance, low beam noise, ion charge states Q=1+ to 3+, beam current ∼0.5 A, pulse width ∼5–20 μs, and repetition rate ∼10 pulses per second. We have explored the suitability of a vacuum arc ion source for this application. Energetic, high current, gadolinium ion beams were produced with parameters as required or close to those required. The performance parameters can all be improved yet further in an optimized ion source design. Here we describe the ion source configuration used, the experiments conducted, and the results obtained. We conclude that a vacuum arc based metal ion source of this kind could be an excellent candidate for heavy ion fusion research application.

A hollow cathode ion source as an electron-beam ion source injector for metallic elements

A hollow cathode ion source (HCIS) has been developed in our Laboratory to produce, by cathodic sputtering in a glow discharge, a one charge metallic ion beam. This source is used as an injector for the electron-beam ion source (EBIS) Dioné that produce, after ion stripping, a highly charged heavy-ion beam for acceleration in Mimas–Saturne synchrotrons. Due to the good pulse-to-pulse repeatability of the HCIS, the very long lifetime of the cathode (several months), as well as the very good value of the normalized emittance (εnorm=4×10−9 π mrad), this source appears as an ideal EBIS injector for metallic and gaseous elements. In this paper we report the description of the HCIS and the experimental results achieved, after injection in the EBIS, by the production of heavy-ion beams like Fe20+, Au50+, and U55+ (from 4×107 to 9×106 ions/cycle).

A study of different ion sources for use in the 205Pb experiment

A very critical feature for the feasibility of the 205Pb experiment is the efficiency of the ion source. As there exist only few data about the ion source efficiency for the production of heavy ion beams, we studied several ion sources probably suitable with respect to the requirements of an AMS experiment with 205Pb ions. The efficiencies achieved are: Penning ion source (Pb 2+) 0.0001, are discharge source (Pb 1+) 0.0005, duoP1Gatron (Pb 2+) 0.002, negative ion sputter source (PbF 3 −) 0.01, laser ion source (Pb 1+) 0.00001. Better results can be expected by improvement of the ion sources including a suitable sample material recycling procedure.

The EBIS-RFQ Couple : A Fully Matched Heavy Ion 3rd Pre-Injector for Saturne

Since 1978, the 3 GeV Synchrotron Saturne is routinely operated with proton, deuteron, helium beams and, since 1981 with polarized protons and deuterons. Heavy ions are expected in the Summer of 1983 by using a new pre-injector presently under construction. As already proposed by R.W.Hamm, the marriage of an EBIS and an RFQ can be looked upon generally as a very good means of production of heavy ion beams at low energy because it combines high charges states, therefore low voltage on the terminal, and low velocity acceleration. After the RFQ, the beam is injected into Saturne through 20 MeV Alvarez linac.

Ion beam studies, part VI: The production of heavy ion beams

A description of techniques for the production of intense beams of heavy ions is given. A table of recommended operational procedures for most elements is included. The ionisation of boron is considered in some detail because of its particular importance as a dopant for ion implantation.