The 80 kJ electrothermal gun facility at Kumamoto University was assembled in order to investigate the phenomena of capillary discharges and to determine parameters of plasmas produced by a high power pulse discharge in the capillary. The behavior of capillary discharges is observed by using an image converter camera in order to make clear the early phenomena of the capillary discharge in different ambient pressures. The behavior of early capillary discharges varies from arc discharge to surface discharges with decreasing ambient pressure. ©1996 American Institute of Physics.