A soft x-ray generator includes a unique pulse trigger assembly which reliably and reproducibly provides a plasma to initiate the discharge between a cathode and an anode, and having a cone-shaped geometry. The soft x-ray generator of the present invention also includes a rotating anode which is generally disk-shaped with an outer circumferential edge which can be rotated with respect to the cathode to expose different sections of the anode to the plasma discharge, thereby reducing anode wear and providing longer term operation. Anode erosion is also reduced by the liquid cooling of the anode during use. The generator utilizes a relatively low capacitance for the cathode-to-anode discharge and a relatively high voltage and pulse repetition rate (frequency) to achieve continuous reproducible results.