On the detection of RF breakdowns in ICRH Resonant Double Loop antennas

摘要

A voltage breakdown in an ion cyclotron resonance heating (ICRH) system is usually detected as an abrupt change in the module of the reflection coefficient |Γ_(in)| at the power source output. The same effect can be due to a large load variation. This paper presents the study of some new concept for detecting voltage breakdowns in ICRH Resonant Double Loop (RDL) systems, to be used in conjunction with the one identifying an arc by the detection of an excessive standing wave ratio (SWR), either at the operating frequency or within the band below the operating frequency. The method should be able to help discriminating fast load variations from voltage breakdowns in any of the in-vessel components under the torus vacuum, and therefore selecting the proper corrective action.