Powerful narrow-band relativistic masers based on advanced Bragg resonators operating at mm and sub-mm wavelength bands

The paper describes recent results of theoretical and experimental studies of powerful relativistic masers based on linac LIU-3000. The key components of the oscillators are advanced Bragg resonators based on coupling of propagating and quasi-cutoff waves that possess high selectivity over transverse coordinates and allows establishment of narrow-band operating regime in strongly oversized system at short wavelengths. At the present stage efficient operation of the JINR-IAP FEM with advanced Bragg resonator has been demonstrated at 30 GHz / 20 MW and 60 GHz / 5 MW powers. Experimental studies of the FEM in W-band is in progress currently. Project of 250 GHz Bragg CARM operating at MW power level and aimed on plasma fusion installations of the next generation is discussed.