A continuous-wave second harmonic gyrotron oscillator at 460 GHz

We report the short pulse and CW operation of a 460 GHz gyrotron oscillator both at the fundamental (near 230 GHz) and second harmonic (near 460 GHz) of electron cyclotron resonance. During operation in a complete CW regime with 12.4 kV beam voltage and 135 mA beam current, the gyrotron generates a record 8 W of power in the second harmonic TE0,6,1 mode at 458.6 GHz. Design at high frequency, second harmonic, and low beam power is challenging because the latter two involve lower gain than at fundamental modes and all three necessitate higher Q cavities. Under complete computer control, the gyrotron has stably operated continuously for over an hour near 460 GHz. Diagnostic radiation pattern measurements of the beam using an array of pyroelectric sensors show a bi-Gaussian beam with 4% ellipticity. Operation in the fundamental modes, including the TE₀ ₃ ₁ mode at 237.91 GHz and the TE₂ ₃ ₁ at 233.15 GHz, is observed at peak output powers up to 70 W. CW studies of the fundamental TE₂ ₃ mode at low voltage reveal that the mode can be excited with less than 7 W of beam power at less than 3.5 kV. Further, we demonstrate broadband continuous frequency tuning of the fundamental modes of the oscillator over a range of more than 2 GHz through variation of the magnetic field alone.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2005

Author dc:creator

• Hornstein, Melissa K. (Melissa Kristen), 1977-

Advisor dc:contributor.advisor

• Richard J. Temkin.

• Electrical Engineering and Computer Science.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/33939
• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Identifier URI

http://dspace.mit.edu/handle/1721.1/33939

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/33939