Environmental advantages of energy recovery from spent beam in sources of millimeter wave power for ECRH in fusion reactors

Millimeter wave power sources for electron cyclotron resonance heating of fusion plasmas are required to supply an estimated CW power of 100 MW. Their typical level of efficiency of generation of millimeter waves from the energy of the electron beam is ≈ 33%. This implies that the prime power for the beam would be ≈ 300 MW. Out of this, 200 MW would be dumped on the collector as heat to be carried away to cooling towers.