Design of a 95 GHz fourth harmonic gyroklystron

Summary form only given, as follows. There is currently an interest in medium power (/spl sim/100 kW), compact 95 GHz amplifiers for future radar applications. Size, weight, and efficiency are critical for airborne applications. The key to success of the amplifier is the advanced center post (ACP) gun, which must produce an axis-encircling electron beam focussed into a 0.064-inch diameter drift tube. Gun simulations incorporating the actual magnetic field and thermal velocity spread in the emitted electrons show that axial velocity spreads of less than 2% are attainable for a lower power gun, which is significantly better than other gun concepts. The amplifier utilizes coaxial-magnetron-type cavities operating in the /spl pi/ mode. In this cavity, vanes extend nearly down to the electron beam's outside diameter. The majority of the RF stored energy in the system is in the coaxial cavity, so that the resonant frequency and quality factor of each coaxial magnetron cavity may be adjusted by varying only the coaxial cavity length. The drift tube diameter of 0.064 inch was chosen to be cut off to all waveguide modes below 103 GHz. To facilitate testing of several devices, the harmonic gyroklystron (HGK) is being designed with flanges between both the electron gun/amplifier and the collector/amplifier. In addition, a low average power collector is used, allowing the entire tube assembly to be inserted through the magnet. This construction method allows different amplifier designs to be tested quickly with the same electron gun and beam optics.