Latest developments on the Dutch 1MW free electron maser

Journal Article · Sat May 01 04:00:00 EDT 1999 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.59045· OSTI ID:690669

Caplan, M ^[1]; Verhoeven, A G; Urbanus, W ^[2]

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1. Lawrence Livermore National Laboratory, 7000 East Ave, L-637 Livermore California, 94551 (United States)
2. FOM Instituut voor Plasma Fysica, Rijnhuizen, P.O. Box 1207, 3430 BE Nieuwegein (The Netherlands)

The FOM Institute (Rijnhuizen, Netherlands), as part of their fusion technology program, has undertaken the development of a Free Electron Maser with the goal of producing 1MW long pulse to CW microwave output in the range 130 GHz{endash}250GHz with wall plug efficiencies of 60{percent}. This project has been carried out as a collaborative effort with Institute of Applied Physics, Nizhny Novgorod Russia, Kurchatov Institute, Moscow Russia, Lawrence Livermore Laboratory, U.S.A and CPI, U.S.A. The key design features of this FEM consists first of a conventional DC acceleration system at high voltage (2MV) which supplies only the unwanted beam interception current and a depressed collector system at 250kV which provides the main beam power. Low body current interception ({lt}25mA) is ensured by using robust inline beam focussing, a low emittance electron gun with halo suppression and periodic magnet side array focussing in the wiggler. The second key feature is use of a low-loss step corrugated waveguide circuit for broad band CW power handling and beam/RF separation. Finally, the required interaction efficiency and mode control is provided by a two stage stepped wiggler. The FEM has been constructed and recently undergone initial short pulse ({lt}10 usec) testing in an inverted mode with the depressed collector absent. Results to date have demonstrated 98.8{percent} beam transmission (over 5 Meters) at currents as high as 8.4 Amps, with 200GHz microwave output at 700kW. There has been good agreement between theory and experiment at the beam current levels tested so far. Details of the most recent experimental results will be presented, in particular the output frequency characteristics with detailed comparisons to theory. The immediate future plans are to operate the system at the design value of 12 Amps with at least 1MW output. The system will then be reconfigured with a 3 stage depressed collector to demonstrate, in the next year, long pulse operation (100 msec) and high wall plug efficiency. Long term future plans call for upgrading the FEM to 2MW and extrapolations up to 5MW are shown to be theoretically possible. {copyright} {ital 1999 American Institute of Physics.}

• Sponsoring Organization: USDOE
• OSTI ID: 690669
• Report Number(s): CONF-981099--
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 474; ISSN 0094-243X; ISSN APCPCS
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
BEAM EMITTANCE
DESIGN
ELECTRON BEAMS
ELECTRON GUNS
ENERGY EFFICIENCY
MASERS
MICROWAVE SPECTRA
TESTING
WIGGLER MAGNETS