Electron gun for powerful large orbit gyrotron

One of the most important tasks in high power electronics is the development of RF sources in the submillimeter wavelength region. One of the most promising sources is the large orbit gyrotron (LOG). But the efficiency of LOGs is rather small - usually a few percent only. So, to obtain a high enough value of the output power, it is necessary to use a powerful electron beam as the RF radiation energy source. Recently in the Nagaoka Institute of Technology, a Marx generator with accelerating voltage U_o of about 400 kV was developed. The combination of such a power supply with a pulse magnet providing an operating magnetic field of 12 T opens the possibility of a LOG to reach the border of the Terahertz frequency range with output power above 1-2 MW. This paper presents a project designing an electron beam formation system with the mentioned power supply. The operation of a LOG at third to fifth cyclotron harmonics is also discussed.