Millimeter-wave free-eiectron maser experiments

F. Hartemann

doi:10.1117/12.2301623

1 December 1990 Millimeter-wave free-eiectron maser experiments

F. Hartemann

Proceedings Volume 1514, 15th International Conference on Infrared and Millimeter Waves; 15145X (1990) https://doi.org/10.1117/12.2301623
Event: 15th International Conference on Infrared and Millimeter Waves, 1990, Orlando, FL, United States

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 TE_11q 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.

Citation Download Citation

F. Hartemann "Millimeter-wave free-eiectron maser experiments", Proc. SPIE 1514, 15th International Conference on Infrared and Millimeter Waves, 15145X (1 December 1990); https://doi.org/10.1117/12.2301623

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