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Proceedings Paper

Millimeter-wave free-eiectron maser experiments
Author(s): F. Hartemann
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Paper Abstract

A Free-Electron Maser (FEM) experiment is currently underway at MIT, in collaboration with TTE (Thomson Tubes Electroniques). The purpose of the experiment is to demonstrate the operation of a FEM in the MW power range, and scalable to high frequencies and long pulses for ECRH and RF acceleration. The electron beam is produced by a 700 kV, 0.27 μperv thermionic electron gun designed and built by TTE. An axial magnetic field of 2.35 kG, produced bv 7 CW water-cooled coils, guides the beam along the interaction region. The wiggler is a 50-period permanent magnet helical wiggler, with a period of 3 cm and a linear introduction taper 10 periods long. The wiggler amplitude is 500 G. In the first stage of the experiment, we have operated the FEM as an oscillator with a TE11q mode structure in the Ka-band, at power levels of 1-2 MW and eficiencies around 5 %. We have also observed low-gain amplification of 28 and 35 GHz signals injected in the interaction region. The resonant voltages are in very good agreement with theory ; in addition, the signature of the amplified signal shows that the FEM operates in the Raman regime.

Paper Details

Date Published: 1 December 1990
PDF: 3 pages
Proc. SPIE 1514, 15th International Conference on Infrared and Millimeter Waves, 15145X (1 December 1990); doi: 10.1117/12.2301623
Show Author Affiliations
F. Hartemann, MIT Plasma Fusion Ctr. (United States)


Published in SPIE Proceedings Vol. 1514:
15th International Conference on Infrared and Millimeter Waves
Richard J. Temkin, Editor(s)

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