A method of arc prevention in high power ICRH systems

The frequent occurrence of voltage breakdowns in ICRH heating experiments requires the development of very efficient methods of automatic arc detection and arc suppression, so as to prevent severe equipment damage in future high power, long pulse systems. This paper presents the concept of an arc prevention system i.e. of a protection system aiming at minimizing the power dissipated in the arc during the suppression process and recovering normal operation only when the arc extinction is actually detected. In this method, the complex impedance of each radiating element (Zs) is continuously measured in real time and, during the process of arc extinction, the arc position and complex admittance Ya continuously measured. An load independent arc alarm signal is generated and used to initiate and terminate the suppression routine.