COOLING OF PARTICLE BEAMS - INTRABEAM SCATTERING, ENVELOPE INSTABILITY AND SHEAR

We investigate the dynamics of strongly coupled beams upon cooling, us ing molecular dynamics (MD) computer simulations. In the quest for cry stalline beams in storage rings one has to overcome shear forces in th e bending magnets as well as emittance growth due to envelope instabil ities and intrabeam scattering (IBS). We show that for zero-current ph ase-advances sigma(0)<90 degrees even one-dimensional longitudinal coo ling is effective, as the beam is stable and the transversal degrees o f freedom are cooled indirectly through IBS. The case sigma(0)>90 degr ees requires very high three-dimensional cooling rates in order to ove rcome envelope instabilities. The influence of the bending angle on th e cooling process is investigated with two independent simulation code s, whose results agree very well.