BASIC LIMITATIONS IN THE RF LINAC STORAGE-RING APPROACH

Ignition of indirectly driven high-gain targets requires a specific po wer of typically 10(16)W/g. Storage ring limitations and space charge effects in final focusing are shown to have an important impact on the minimum number of beams incident on the target. The increase in this number, if compared with the earlier HIBALL design, is largely due to the more stringent focusing requirements from indirect drive and a mor e careful evaluation of space charge effects. We compare the consequen ces on driver design of a two-converter target using 10 GeV ions with a << hotraum >> target using 5 GeV ions. Parameters can be identified for which both scenarios have comparable risk in terms of exceeding co nventional accelerator thresholds. For the 10 GeV case a spot radius o f 3 mm is clearly more realistic (from the driver point of view) than the previously considered 1.3mm radius.