Investigation of beam stability in a high intensity drift tube linac for heavy ion inertial fusion

With the new concept of indirectly driven targets for heavy ion inertial fu sion, the driver scenarios had to be reconsider-ed. A European study group (HIDIF collaboration) investigated the feasibility of a driver facility bas ed on a linac and storage ring approach (Hofmann and Plass (Eds.), GSI-98-0 6 GEP, Darmstadt, 1998). In a preinjector consisting of an array of ion sou rces, rf-linacs and funnel devices a 400 mA Bi+ beam is formed, which is fu rther accelerated in a main linac from about 2 GeV to its final energy of 1 0 GeV and then injected into the rings for storage and pulse compression. T he most important requirements for the beam dynamics layout of this high in tensity heavy ion linac are transmission rates of nearly 100% and very low emittance growth to avoid particle losses along the linac and at ring injec tion which may cause radioactivation of the structures. A particle dynamics design of an Alvarez type drift tube linac (DTL) has been successfully car ried out with respect to high stability of the beam against errors and mism atch, which was checked by multiparticle simulations. Statistical errors of rf field amplitude and phase and quadrupole gradients were taken into acco unt as well as current fluctuations, initial mismatch modes and changes of particle input distributions and combinations of different errors. Results of Monte Carlo simulations with up to 20,000 particles show a smooth behavi our of the beam and small halo development only. In addition the "telescopi ng" option, where three different ion species are accelerated, and the nece ssary modifications for the linac, have been investigated. (C) 2001 Elsevie r Science B.V. All rights reserved.