“…First, for the accelerator, which is designed to operate at fixed beam power level, the coupling factor is adjusted to the value that is optimal for the given power level. Second, for the accelerator, beam power of which may change, but not very often, we set the tuning element near the coupling iris, which, depending on its position, allows one to change the coupling factor over a wide range [15]. Third, we have developed a method for fast change of the coupling factor using a tuning plunger located near the iris [16].…”