The advantages of on‐demand pulse charging of high‐voltage (HV) capacitors are discussed, highlighted by use of the technique to reduce the pulse width of a nitrogen laser to subnanosecond. Pulse charging reduces the HV stress on the capacitor dielectric resulting in a more compact laser reducing the discharge time of the laser strip‐line capacitor. The HV pulse for charging is produced by switching a low‐voltage capacitor via a step‐up coil into the HV strip‐line capacitor which is then immediately discharged. The system reduces the on‐charge duty cycle to below 0.001.