CNRS-IN2P3/LPSC, Grenoble
The basic principles of the ECR charge state breeder (CSB) are recalled, special attention is paid to the critical parameters allowing the optimization of the ECR charge breeders characteristics (efficiency yield, charge breeding time, capture potential deltaV). An overview is given on the present ECR charge breeders situation and results worldwide. Possible means to increase the 1+ ion beam capture for light ions is presented. In the context of radioactive environment, possible technological improvements and/or simplifications are suggested to facilitate the maintenance and to reduce the human intervention time in case of a subsystem failure.
ANL, Argonne
Funding: Work supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
The construction of the Californium Rare Ion Breeder Upgrade (CARIBU), a new radioactive beam facility for the Argonne Tandem Linac Accelerator System (ATLAS), is nearing completion. The facility will use fission fragments from a 1 Ci 252Cf source; thermalized and collected into a low-energy particle beam by a helium gas catcher. In order to reaccelerate these beams, the existing ATLAS ECR1 ion source was redesigned to function as an ECR charge breeder. The helium gas catcher system and the charge breeder are located on separate high voltage platforms. An additional high voltage platform was constructed to accommodate a low charge state stable beam source for charge breeding development work. Thus far the charge breeder has been tested with stable beams of rubidium and cesium achieving charge breeding efficiencies of 5.2% into 85Rb17+ and 2.9% into 133Cs20+.
JYFL, Jyväskylä
Funding: This work has been supported by the Academy of Finland under the Finnish Centre of Excellence Programme 2006-2011 (Nuclear and Accelerator Based Physics Programme at JYFL).
The accelerator based experiments at JYFL (University of Jyväskylä, Department of Physics) range from basic research in nuclear physics to industrial applications. A substantial share of the beam time hours is allocated for heavy ion beam cocktails, used for irradiation tests of electronics. Producing the required ion beam cocktails has required active development of the JYFL ECR ion sources. This work is briefly discussed together with the implications of the beam cocktail campaign to the beam time allocation procedure. The JYFL ion source group has conducted experiments on plasma physics of ECR ion sources including plasma potential and time-resolved bremsstrahlung measurements, for example. The plasma physics experiments are discussed from the point of view of beam cocktail development.
JYFL, Jyväskylä
Funding: This work has been supported by the Academy of Finland under the Finnish Centre of Excellence Programme 2006-2011 (Nuclear and Accelerator Based Physics Programme at JYFL).
The activities of the JYFL ion source group cover the development of metal ion beams, improvement of beam transmission and studies of Electron Cyclotron Resonance Ion Source (ECRIS) plasma parameters. The development of metal ion beams is one of the most important areas in the accelerator technology. The low energy beam injection for K-130 cyclotron is also studied in order to improve its beam transmission. It has been noticed that the accelerated beam intensity after the cyclotron does not increase with the intensity extracted from the JYFL 14 GHz ECR ion source, which indicates that the beam transmission efficiency decreases remarkably as a function of beam intensity. Three possible explanations have been found: 1) the extraction of the JYFL 14 GHz ECRIS is not optimized for high intensity ion beams, 2) the solenoid focusing in the injection line causes degradation of beam quality and 3) the focusing properties of the dipoles (analysing magnets) are not adequate. In many cases a hollow beam structure is generated while the origin of hollowness remains unknown.
LBNL, Berkeley
Funding: This work was supported by the Director, Office of Energy Research, Office of High Energy and Nuclear Physics, Nuclear Physics Division of the U.S. Department of Energy under Contract DE AC03-76SF00098.
The development of the superconducting 28 GHz ECR ion source VENUS at the Lawrence Berkeley National Laboratory (LBNL) has pioneered high field superconducting ECR ion sources and opened a path to a new generation of heavy ion accelerators. Because of the success of the VENUS ECR ion source, superconducting 28 GHz ECR ion sources are now key components for proposed radioactive ion beam facilities. This paper will review the recent ion source development program for the VENUS source with a particular focus on the production of high intensity uranium beams. In addition, the paper will discuss a new R&D program started at LBNL to develop ECR ion sources utilizing frequencies higher than 28 GHz. This program addresses the demand for further increases of ion beam intensities for future radioactive ion beam facilities. The most critical technical development required for this new generation of sources is the high-field superconducting magnet system. For instance, the magnetic field strengths necessary for 56 GHz operation produce a peak field in the magnet coils of 12-14 T, requiring new superconductor material such as Nb3Sn. LBNL has recently concluded a conceptual, comparative design analysis of different coil configurations in terms of magnetic performance and has developed a structural support concept compatible with the preferred magnetic design solution. This design effort concludes that a sextupole-in-solenoid ECR magnet structure (VENUS type) is feasible with present Nb3Sn technology, but that an inverted geometry (solenoid-in sextupole) exceeds the capability of Nb3Sn superconductors and can be ruled out as candidate for a 56 GHz ECR ion source.
BNL, Upton
Funding: Work supported under the auspices of the US Department of Energy and the National Aeronautics and Space Administration.
At Brookhaven National Laboratory, a high current Electron Beam Ion Source (EBIS) has been developed as part of a new preinjector that is under construction to replace the Tandem Van de Graaffs as the heavy ion preinjector for the RHIC and NASA experimental programs. This preinjector will produce milliampere-level currents of essentially any ion species, with q/A≥ 1/6, in short pulses, for injection into the Booster synchrotron. In order to produce the required intensities, this EBIS uses a 10A electron gun, and an electron collector designed to handle 300 kW of pulsed electron beam power. The EBIS trap region is 1.5 m long, inside a 5T, 2m long, 8” bore superconducting solenoid. The source is designed to switch ion species on a pulse-to-pulse basis, at a 5 Hz repetition rate. Singly-charged ions of the appropriate species, produced external to the EBIS, are injected into the trap and confined until the desired charge state is reached via stepwise ionization by the electron beam. Ions are then extracted and matched into an RFQ, followed by a short IH Linac, for acceleration to 2 MeV/A, prior to injection into the Booster synchrotron. An overview of the preinjector is presented, along with experimental results from the prototype EBIS, where all essential requirements have already been demonstrated. Design features and status of construction of the final high intensity EBIS is also be presented.
Goethe Universität Frankfurt/IAP, Frankfurt
MSU/NSCL, East Lansing
ECR and EBIS have become well-known ion sources for most heavy ion accelerator projects. The basic difference arises from the method, how energy is provided to create dense energetic electrons: An ECR uses microwave heating of a magnetically confined plasma, while in an EBIS the energy comes from a power supply to accelerate an electron beam and focus it to high density in a strong solenoidal magnetic field. Basically ECR sources are dc sources of heavy ions but the afterglow extraction also provides intense mA pulses in ms. In contrast to this EBIS sources provide an intense ion pulse in 1-100 μs and therefore find application in feeding synchrotrons. This determines most of the accelerator applications: ECR sources have very successfully extended the range (and life) of cyclotrons, while EBIS has found application at high energy facilities. For radioactive beam facilities, both kind of sources are in use. ECR sources in the trapping mode (ECRIT) perform the ionization (charge breeding) of high intensity primary beams, while EBIS can reach higher charge states at lower emittance, which provides an improved signal to noise ratio for rare isotopes.
TU Dresden/IAP, Dresden
DREEBIT, Dresden
FZD, Dresden
Electron Beam Ion Sources (EBIS) are powerful tools to produce ions over a wide ion charge spectrum for nearby all elements. A wide spectrum of very different applications of EBIS is known. The EBIS are used in basic research as well as in applications of different fields of technology but also in conjunction with particle accelerators. With the Dresden EBIS ion source family compact ion sources for the production of highly charged ions (HCIs) as platform technology for a wide field of applications are available. The Dresden EBIS-A is a compact, long-term stable room-temperature ion source and the Dresden EBIS-SC a new superconducting high-current EBIS for the production of high currents of HCI. Significant parameters of these ion sources are compared in the present paper. This paper discusses the performance of the presented ion sources for the production of HCIs, compare the sources with other existing machines and discusses the usability of the Dresden EBIS sources in connection with different types of accelerators. It is shown that the sources are particularly suitable for applications in medical particle therapy. The outstanding properties of the EBIS favor them for use with CYCLINACS, Rapid Cycling Medical Synchrotrons and complex synchrotron based medical irradiation facilities.
Michigan University/MIBL, Ann Arbor
The Michigan Ion Beam Laboratory (MIBL) at the University of Michigan has instruments equipped with ion sources capable of generating a wide variety of ions. The 1.7-MV Tandem accelerator can operate with three different sources: a Torvis source, a Duoplasmatron source and a Sputter source. The 400-kV ion implanter is equipped with a CHORDIS source that can operate in three different modes (gas, sputter, and oven) and is capable of producing ion beams for most of the elements in the periodic table. In this work, we discuss the principle of operation of each source, their performances and the latest applications and projects conducted at MIBL using these sources.