Drift compression experiments on MBE-4 and related emittance growth phenomena

A series of experiments was conducted on the MBE-4 heavy ion accelerator in which a velocity tilt was placed on the beam in the first accelerating section beyond the injector, followed by drift compression over the remaining 11 m. Depending upon the magnitude of the velocity tilt and the accompanying mismatch in the focusing lattice, emittance growth was observed, manifested by ´butterfly´ shapes in x-x´ phase space. A discussion is presented of various analytical limits on ion beam compression, and these are related to these experiments and also to a driver for a heavy ion fusion reactor. Also presented are numerical simulations which are used to investigate various aspects of compression and consequent emittance growth.<>