Low-order-mode harmonic multiplying gyrotron traveling-wave amplifier in W band
- Department of Electro-Optical Engineering, Southern Taiwan University, Tainan, Taiwan (China)
- Department of Communication Engineering, National Penghu University of Science and Technology, Penghu, Taiwan (China)
- Department of Physics, National Tsing Hua University, Hsinchu, Taiwan (China)
Harmonic multiplying gyrotron traveling-wave amplifiers (gyro-TWAs) allow for magnetic field reduction and frequency multiplication. To avoid absolute instabilities, this work proposes a W-band harmonic multiplying gyro-TWA operating at low-order modes. By amplifying a fundamental harmonic TE{sub 11} drive wave, the second harmonic component of the beam current initiates a TE{sub 21} wave to be amplified. Absolute instabilities in the gyro-TWA are suppressed by shortening the interaction circuit and increasing wall losses. Simulation results reveal that compared with Ka-band gyro-TWTs, the lower wall losses effectively suppress absolute instabilities in the W-band gyro-TWA. However, a global reflective oscillation occurs as the wall losses decrease. Increasing the length or resistivity of the lossy section can reduce the feedback of the oscillation to stabilize the amplifier. The W-band harmonic multiplying gyro-TWA is predicted to yield a peak output power of 111 kW at 98 GHz with an efficiency of 25%, a saturated gain of 26 dB, and a bandwidth of 1.6 GHz for a 60 kV, 7.5 A electron beam with an axial velocity spread of 8%.
- OSTI ID:
- 22086156
- Journal Information:
- Physics of Plasmas, Vol. 19, Issue 9; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
Similar Records
G-band harmonic multiplying gyrotron traveling-wave amplifier with a mode-selective circuit
High-power gyrotron traveling-wave amplifier with distributed wall losses and attenuating severs