Gyrotrons, state of the art

Gyrotrons are electron tubes in which electron energy conversion to the RF- field occurs transverse to the electron beam direction, in contrast to the process in Klystrons. Moreover the frequency of the generated oscillation i s not the lowest resonance frequency of the resonator but the frequency of a higher order transverse mode. Hence, to fulfil the energy conversion the electron must exhibit velocity components in transverse direction. They mov e on helical trajectories in a longitudinal, static magnetic field, In the report design, mechanism and state of the art of the Gyrotron are tr eated and also different partial problems today in lively development. Only the Gyro-Oscillator, the Gyromonotron, in the following called Gyrotron, i s discussed. It seems possible to obtain more than 1 MW CW power in the 140 GHz region. F. i. 0,55 MW were realized at 140 GHz with 3,0 s pulse length. Working wit h a single stage depressed collector voltage efficiencies are raised to 50% . World-wide built Gyrotrons for frequencies between 70 to 300 GHz are in c ommerce. Gyrotrons in the region over 100 GHz have applications in fusion p lasma heating and plasma diagnostics.