High Voltage Thyristor Switch

Summary form given only. A repetitive pulse power modulator has been designed and constructed for use in the FELIX (Free Electron Laser for Infrared experiments) project. The main components of the modulator are a pulse forming network (PFN) and a semiconductor switch. The PFN is made of four parallel lines, each containing 19 cells of a capacitor and an inductor. The semiconductor switch consists of 20 high voltage thyristors which are stacked in series. The energy in the PFN is transferred into a pulse transformer by means of the semiconductor switch. The pulse transformer produces the appropriate klystron voltage. With this configuration, it is possible to achieve a peak current of 2.5kA with a pulse width of 20 mus at a frequency of 20Hz. Under these circumstances, the expected lifetime of the modulator is more than ten years.