Abstract
Operating Ion Cyclotron Resonance Heating (ICRH) antennas at high power density puts them at
risk of arcing which reduces the coupled power to the plasma because the perturbed impedance
match triggers the Voltage Standing Wave Ratio (VWSR) based generator trip system but even
worse might damage the antenna beyond repair because of the the arc’s localised energy deposition.
New antennas are designed to operate in a load tolerant way which creates low impedance zones
that are especially at risk since the existing VSWR protection systems are less sensitive to arcs in
these areas. To protect these low impedance areas, a new arc protection system referred as Scattering
Matrix Arc Detection (SMAD) was proposed. This paper describes the basic operating principle
and implementation in hard- and software for the JET ITER-Like Antenna (ILA), with testbed and
preliminary JET commissioning results.
