Voltage controlled MESFET pulse shape generator

A programmable pulse shape generator capable of producing pulse shapes for Nova and Beamlet has been designed and simulated using the circuit code SPICE. The design utilizes power MESFETS, which are commonly used in microwave amplifiers. The pulse shape is varied by setting a bias voltage on each in a chain of MESFETS with a 200 ps temporal resolution. The electrical pulse then drives an integrated electro-optic modulator similar to what is on Beamlet. Pulse shapes 22 and 25, used on Nova, have been generated by this design. There is no fundamental barrier to making such a pulse generator for use on the National Ignition Facility. In fact, the longer time scales on the NIF pulse will ease the high speed requirements of the pulse shape generator allowing the use of less expensive components. The next step will be to build a prototype circuit for initial testing on Beamlet and Nova.