Theory and Experiment of a Heavily Loaded 94 GHz Gyrotron Traveling-Wave Amplifier
Abstract
A high power gyro-TWT amplifier operating in the low-loss TE_01 mode has been fabricated and is under test at UCD. Envisioned applications include next generation millimeter wave radar. It is driven by an 80 kV, 5 A electron beam with a pitch angle (v_⊥/v_allel) of ng 1 and velocity spread of 5%. The amplifier is predicted by large-signal simulations to generate 140 kW at 92 GHz with 28% efficiency, 50 dB saturated gain and 5% bandwidth. The stability of the amplifier from oscillation has been checked with linear codes. The threshold current for the absolute instability of the TE_01 operating mode for the chosen operating parameters is predicted to be 10 A. To suppress potential gyro-BWO interactions involving the TE_02, TE_11, and TE_21 modes, the interaction circuit with a cutoff frequency of 91 GHz has been loaded with loss so that the single-pass attenuation is 90 dB at 93 GHz. A coaxial input coupler with 3% bandwidth is employed with a predicted and measured coupling of 1 dB and 2 dB, respectively. Hot test measurements, including gain, saturated output, and stability will be described.
- Publication:
-
APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- October 2003
- Bibcode:
- 2003APS..DPPLI2005L