Cyclotron resonance masers with trochoidal electron beams

Summary form only given, as follows. A long time ago the development of cyclotron resonance masers (CRMs) was started utilizing beams of electrons moving along either helical trajectories in a constant magnetic field or trochoidal trajectories in crossed electric and magnetic fields. The development of CRMs with helical electron beams has led to the invention of gyrotrons that are well known nowadays. The development of CRMs with trochoidal beams (let us call them trochotrons) was stopped in the mid-60s because these devices were unable to compete with gyrotrons in mastering a short-millimeter and submillimeter wavelength region. At the same time, trochotrons have some potential advantages. Among them the most important is a principle possibility to produce electron beams with low axial velocity spread (in the absence of space charge fields). This can be especially important for operation at traveling waves in wide-band amplifiers and Doppler frequency up-shifted devices. In this work we present some simple estimates demonstrating capabilities of trochotrons and their scaling laws. Also, the linear theory of these devices operating at traveling waves is presented and an operation at some specific modes is discussed.