ION SOURCES FOR FISSION FRAGMENT ACCELERATORS

At the Grenoble and Munich high-flux reactors fission fragment acceler ators are under design which will deliver beams of very neutron-rich f ission products with a final energy between 3 and 6 MeV/u. In order to obtain an efficient acceleration in a compact accelerator, charge con version of the 1+ ion beams from the in-pile ion source to a q/A great er than or equal to 0.16 has to take place. In the chain from producti on to acceleration, Ion sources are the key elements to reach high bea m intensities of over 10(10) s(-1). For the in-pile part the target-io n source assembly has not only to be very efficient, but should also b e highly selective for the desired elements (which go from nickel to e uropium) on one hand and robust against the hostile environment (high neutron and gamma flux) on the other hand. Foreseen types are a surfac e ionization source, which could also be run as laser ion source for r esonant photo ionization, and, for rare gases, a plasma ion source cou pled via a transfer line to the target. For the charge state breeding several different schemes are considered: the combination of a Penning trap for bunching, cooling, and mass separation and an electron beam ion source (EBIS) as charge breeder, similar to REX-ISOLDE, an EBIS wi th direct injection of a de beam of 1+ ions (''accu-EBIS'') or an elec tron cyclotron resonance ion source (ECRIS) with either continuous or bunched extraction. The EBIS may provide higher charge states, whereas the ECRIS is able to work with much higher beam intensities and allow s cw-operation. The advantage of each scheme is explained and some des ign requirements of the different sources are presented. (C) 1998 Amer ican Institute of Physics. [S0034-6748(98)65402-2].