Confocal and non-confocal negative branch unstable reaonators with an intracavity spatial filter have been applied to a high-gain short-pulse UV preionized XeCl laser. The near-and far-field radiation characteristicis have been investigated in both configurations for different spatial filter diameter values. Laser beams of quite high brightness and with a regular intensity spatial profile have been obtained, in Particular laser beams of higher brightness have been obtained with uon confocal schemes. A maximun beam brightness of 1.3×1014 W/(cm2s) has been achieved. A low sensitivity to mirror misalignments has also been observed.