High power W-band gyro-BWO experiments

Summary form only given. Experimental results will be presented of a frequency tunable gyrotron backward wave oscillator (gyro-BWO). A helically corrugated interaction region (HCIR) was used to allow efficient interaction over a wide frequency band at the second harmonic of the electron cyclotron frequency without parasitic output [1-5]. The gyro-BWO generated a maximum output power of 12 kW when driven by a 40 kV, 1.5 A, annular-shaped large-orbit electron beam and achieved a frequency tuning band of 88-102.5 GHz by adjusting the cavity magnetic field [6]. The performance of the gyro-BWO is in excellent agreement with 3D particle-in-cell (PIC) numerical simulations. Further experimental plans with a quasi-optical mode [7] converter and energy recovery [8] system will be presented.