  At COSY, electron cooling is used after stripping injection of H- or D- ions
in order to prepare phase-space-dense ion beams before acceleration to a
requested energy. The electron-cooled beam has been successfully applied for
specific external experiments. The achievable beam intensity is limited by
instabilities during the cooling process. Besides initial losses after
injection, as long as the beam has still large emittances, the self-excitation
of coherent betatron oscillations is the dominating beam loss mechanism.
Perspectives for possible improvements are briefly addressed.
