Comparison of different collector coil concepts for high power CW gyrotrons

High power CW gyrotrons usually use an axial solenoidal collector coil to sweep the electron beam vertically, thereby decreasing the average power density on the collector wall. Unfortunately high power load densities may remain at the turning points of the beam at the bottom and top of the absorbing area. An alternative collector coil concept using two dipole coil pairs attached to the lower part of the collector is under investigation. This should create a rotating tilted electron beam. Both concepts are compared considering peak power load on the collector wall and technical feasibility.