Beam dynamics of cooled heavy ion beams

Evaluation of the collectively modified Schottky spectra as well as beam transfer functions for Ar/sup 18+/ and Kr/sup 36+/ at 250 and 150 MeV/u, respectively, is in agreement with theoretical predictions. Maximum observed phase space densities are compared with thresholds of the microwave instability and with intrabeam scattering. The conventional Keil-Schnell threshold is exceeded in experiment by a factor of 3, with intrabeam scattering as the main limitation. Implications of these results for a heavy ion fusion driver are discussed.<>