Research on ion induction linacs at Berkeley

Since October 1983 most of the research in the USA on heavy-ion fusion (HIF) has been devoted to the physics and technology of the induction linac driver. The economic viability of the method was confirmed in the recent HIF systems assessment study. Research at Berkeley comprises three experimental activities: (a) the multiple-beam experiment, MBE-4, which accelerates four parallel, separately focused beams of cesium ions from 0.2 to 1 MeV, and in which amplification of the beam power by a factor of nearly 40 is observed; (b) development of a 16-beam pulsed 2 MV injector; and (c) a single beam transport experiment (SBTE) for studying collective phenomena in ion beam transport. In addition, a major activity has been the development of a physics and engineering design for a larger experiment to test (in a scaled way) almost all of the manipulations needed in a full-scale driver. A complicating feature in the design is the combining of beams (in sets of four to one); the penalty in collectively enhanced emittance growth must be balanced against the cost savings gained in a driver. (orig.)