Highly Efficient Technological Gyrotron System with Magnetically Shielded Solenoid

In this report, we present the first results of testing a new technological gyrotron at the first cyclotron harmonic with a radiation frequency of 28 GHz and a power of over 20 kW. The generation efficiency reaches 55% at a power level of 6 kW without a system for recuperating the residual electron energy. The efficiency of the entire installation is above 35% in the mode of maximum radiation power, which is achieved by using a magnetically shielded oil-cooled solenoid. The results obtained confirm the operability of the developed electron-optical system under conditions of a sharp drop in the magnetic field of the main solenoid outside the magnet bore. Experimental data are consistent with the results of numerical simulation. This is to hope for the implementation of generators up to the W frequency band using the same magnetic system and high-voltage power supplies.