Solid state Spiker-Sustainer-circuit for XeCl long pulse Excimerlaser

Abstract

For effective excimer laser pumping high voltage pulses with the pulse duration of 100ns and energies from a fraction of joules to some 10 joules are necessary. This energy is deposited via a gas discharge into the laser vessel. The generation of these pulses traditionally provided by Thyraton circuits. The limited lifetime and repetition rates of such a device does not fulfill the requirements of a modern excimer laser. Some medical application requires long pulse (more than 100ns) Excimer laser radiation (308nm). In these cases there is impedance mismatch of the circuit and the laser. The result is a low efficiency (ca 1%) and high stress of the components due to the reflected energy. To overcome this normally Spiker-Sustainer circuits are used. The Spiker ignites the discharge with a short (50ns) high voltage (40kV) low current pulse (1kA). The Sustainer circuit delivers the energy in a low voltage (8kV) long (300ns) high current (10kA) pulse. The Sustainer circuit is matched to the ignited discharge (0.3Ω), hence nearly no reflection occurs and the efficiency is improved (up to 3%). In this work a new approach is presented. A compact pulse forming Spiker-Sustainer circuit with solid state switches enables long pulse Excimerlaser radiation. The focus of this work is the general design and outline of the new circuit. Illustrated by the portions given in this document.