Frequency Tuning and Spectrum Control in Sub-THz Gyrotrons

We present the results of recent IAP RAS investigations, which were aimed at controlling the radiation frequency and spectrum of sub-THz medium power gyrotrons. Different methods of extending the smooth frequency tuning band and providing high frequency stability in CW regimes are discussed. The development of gyrotrons with stated parameters are of interest for many modern applications, including DNP/NMR and RAD spectroscopy, direct measurements of positronium hyperfine structure, diagnostic of various media, etc.