High power wideband gyrotron backward wave oscillator operating towards the terahertz region

Experimental results are presented of the first successful gyrotron backward wave oscillator (gyro-BWO) in the low terahertz region. 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. The gyro-BWO was measured to generate a maximum output power of 12 kW in a continuous frequency tuning band of 88-102.5 GHz when driven by a 40 kV, 1.5 A, annular-shaped large-orbit electron beam. The performance of the gyro-BWO is consistent with 3D particle-in-cell (PIC) numerical simulations.