Quasi-Optical Gyrotron With Arbitrary Beam Injection Angle

In quasi-optical gyrotrons the beam injection angle (angle between the electron beam and radiation beam) has considerable influence on the gain, harmonic operation and efficiency. This paper investigates the effect on the gain mechanism. Two regimes of operation are identified, namely gain nearly proportional to 12 (1 is the interaction length) for small angles and gain nearly proportional to l for large angles. The transition angle separating the two regimes is found and is approximately given by (A/1)' / 2 where A is the wave length. By choosing the parameters appropriately one can run the gyrotron in the high gain regime. *Visiting scientist from Zhejiang Univ., Hangzhou, P. R. China