The output energy of 0.75 J has been obtained with a pulse width of 40 ns and an efficiency of 0.8% by using a uv‐preionized KrF amplification system. The stored energy in an amplifier has been improved by a factor of about 1.6 by control of self‐breakdown voltage with a change of electrode separation. The measured saturation energy for this device was 51 mJ/cm2corresponding to a KrF saturation intensity of 1.2 MW/cm2. The small‐signal gain coefficient reached 4.3%/cm at a charging voltage of 35 kV.