Powerful gyrotrons

Some of the principal ideas and methods of gyrotron theory that are most current and fruitful are examined. The main components of the gyrotron are a magnetron-type electron gun and an open high-selectivity cavity represented by a section of slightly irregular waveguide. A number of relatively old but still significant results from rather rare publications are presented so that researchers need not derive them afresh. A general theory is given of the interaction between electrons rotating in the external magnetic field and the RF field of the resonators and waveguides. Together with a simplified drift adiabatic description of the operating gyrotron gun, a number of new numerical methods of computation (and results based on them) are presented for guns with enhanced current. The problems of mode selection essential for gyrotrons with extended interaction space are discussed. Finally the state of the art and possible further increases in the microwave power and operating frequency are considered.