Inverse magnetron injection gun for a coaxial 1-5MW, 140 GHz gyrotron

A 50 A electron gun with a beam power of 4-5MW for a 1-5MW, 140GHz coaxial gyrotron has been designed, manufactured and tested. An axial rod close to the ground (anode) potential is surrounded by the cathode. The gun is of the diode type with no independent adjustment of the velocity ratio α. Therefore only a low influence of the mechanical tolerances on a can be accepted. The beam properties have been measured using scaled-down parameters. The experimental values of [he velocity ratio agree well with calculation. The measured velocity distribution shows a transverse velocity spread δβ⊥≤15%.