Simulations of high power gyrotron operation during window Arc

During tests of a megawatt-class 140 GHz gyrotron for the fusion experiment Wendelstein 7-X, a window RF arc was documented with a high-resolution spectral measurement system. The arc event coincided with strong perturbations of the nominal cavity mode TE-
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and a final mode switch to a neighbor mode. Simulations using a self-consistent interaction code (SELFT) have reproduced the main features of the event and provide additional information on the development of the modes during the window RF arc.