Summary form only given. Plasma Immersion Ion Implantation (PIII) is a technology used to modify the material surface properties of a variety of products, e.g. for the manufacturing of semiconductor junctions and oxides, and for the production of high-strength, light-weight corrosion-resistant aerospace components. PIII applies a series of negative high-voltage pulses to a sample (target) immersed in plasma. High-Voltage Pulse Generator was built in a circuit category of Pulse Forming Network (PFN), consisting of 10 LC sections with L=100 /spl mu/H, C=2.5 nF and metglas core high-voltage pulse transformer. The instrument was designed to produce an adjustable, several amperes, flat 100 kV pulse with 10 /spl mu/s duration and pulse repetition frequency (PRF) from 50 Hz to 7 kHz. The generator is fed with sine wave, constant high current source, and 20 kV, 3 A switching power supply.