Design and Development of High Voltage Scheme for a Crowbar in RF Heating

Plasma is a mixture of freely moving charged particles. To sustain these particles in ionic state, very high temperature is essential. RF heating systems are utilized for obtaining high temperatures. Arching phenomenon in these systems can cause enormous damage to the RF tube. Fast switching circuit breakers are used to cutoff the load from the supply in cases of arcing. The crowbar interrupts the connection between the high voltage power supply (HVPS) and the RF tube for a temporary period during which the series switch has to open. This paper presents the design and development of Crowbar based on fiber optic triggering for the protection of RF heating system. The importance of optical triggering and utilization of fiber optic has been justified. Protection techniques other than crowbar are briefly discussed. The design of Crowbar is well supported with the experimental results.