this article, we demonstrate efficient laser cooling in novel bunch forms using non-resonant bunching devices. Arbitrary bunch potentials can be designed which offer great flexibility in controlling the cooling conditions. We have performed a detailed comparison between electron cooling and laser cooling of ions in square-well bunch potentials (barrier buckets). In barrier buckets, the cooled ions do not experience external forces in the longitudinal direction. It is therefore possible to achieve ultra-cold ion ensembles with constant longitudinal ion density. Thus, one attains a quasi-coasting, chopped ion beam. As an additional feature, barrier buckets allow one to change the bunch length by externally varying the on/off-ratio (duty cycle) of the potential. The longitudinal ion density in a bunch can thus be directly controlled, which is of particular interest in view of the investigation of space-charge effects and Coulomb-ordering phenomena