Development of a vacuum arc ion source for injection of high current uranium ion beam into the UNILAC at GSI
To fill up the GSI heavy ion synchrotron (SIS) to its space charge limit with uranium ions, a vacuum arc ion source, based on the metal vapor vacuum arc (MEVVA) IV ion source, has been developed and implemented into operation. The ion source has proven its capability in several long period beam times at the high current injector at GSI. With the ion source it was possible to exceed the space charge limit of 15 mA U4+ ions at the entrance of the linear accelerator (UNILAC). The reliability as well as the noise behavior has been improved to such a degree, that this ion source can be used for injection into an accelerator without objection. In this article we present the improvements of the ion source with the most important operational data. The emission current density of the ion source has been increased from 60 mA/cm2 for the common used GSI-MEVVA to 170 mA/cm2. This results in a full beam ion current of 156 mA at 35 kV with a fraction of fourfold charged uranium ions of 67%. The analyzed U4+ ion beam after dc postacceleration amounts to 25 mA at 131 kV which is 1.7 times higher than the requested ion beam current at the entrance of the radio frequency quadrupole. The reduced power density of the vacuum arc results in a higher efficiency and longer lifetime. Solenoids which are creating magnetic fields to enhance the charge state of the ions are no longer placed inside the vacuum system. This ion source design results in a higher availability after ion source replacement at the injector, and longer lifetime. more...
2004 American Institute of Physics. [DOI:10.1063/1.1691516]
Author: R. Hollinger et al.
Comparison of different extraction and acceleration systems for a high intense proton beam for the future proton linac at GSI
For the injection into the future proton LINAC at GSI, the ion source and low energy beam transport system has to deliver a 100 mA proton beam with approximately 100 keV at the entrance of the radio frequency quadrupole within an acceptance (normalized, rms) of 0.2 π mm mrad. The proton yield provided by the ion source should be 90% or higher, whereas the emittance should be as small as possible. The article presents the results of computer simulations done with AXCEL-INP for three different extraction and acceleration systems: a compound system, a pentode extraction system, and a combination of a triode extraction system followed by a separately screened dc acceleration system. These systems will be discussed in terms of beam brightness and facile handling for beam time operation. more...
2004 American Institute of Physics. [DOI: 10.1063/1.1702123]
Author: R. Hollinger et al.
Charge sensitive evaluated ion and electron energy distributions of a vacuum arc plasma
A metal vapor vacuum arc type ion source has been developed for the high current injector at the GSI accelerator facility for the production of high charge state uranium beams. This ion source provides a high intensity ion beam with a fraction of fourfold charged uranium ions up to 67% for injection into the linear accelerator. As part of the ion source development the ion and electron energy distributions have been measured with an electrostatic cylinder spectrometer device which discriminates charged particles with different energy to charge ratios. This allows a charge sensitive evaluation of ion energy distribution. Energy distributions have been measured for various discharge parameters, i.e., arc current, magnetic flux density, and cathode materials. Some important plasma parameters can be derived from these measurements: charge resolved ion energy distributions, mean electron energy and temperature, and the anode drop which in all support the development of a model of a vacuum arc plasma consisting of high charge states. more...
2004 American Institute of Physics. [DOI:10.1063/1.1691518]
Author: M.Galonska et al.