Feasibility study on a highpower (IMW) millimetre-wave (140 GHz) transmission system for diagnostics of fusion and particles in JET by collective millimetre-wave scattering
The technical feasibility of a high power millimetre wave (up to 1MW at 120-160 GHz) transmission line system and the antenna structures for the injection of mm-waves through a vertical and a horizontal port into the JET torus, for diagnostics of fusion alpha particles by collective scattering, is discussed in this report. Two major possibilities for such a MW transmission system at frequencies around 140 GHz have been considered: - oversized, circular, circumferentially corrugated HE(11) hybrid mode waveguide with I.D. = 88.9mm, - quasi-optical transmission through a Gaussian beam reflector waveguide. The preferred approach is a combination of these methods, although for long-distance transmission of millimetre waves the HE(11) waveguide is advantageous. Two possible launching systems are proposed: a version with unfocused beams which are launched directly from the oversized waveguides (divergent beams) and an improved version with focused beams and therefore with increased spatial resolution and parallel wavefronts in the scattering volume. The proposed 1 MW transmission and launching system is, with the exception of the HE(11) feeding optics at the input, independent of the gyrotron output mode.
Bibliographic Reference: Report: JET-R(88)14 EN (1988)
Availability: Available from the Publications Officer, JET Joint Undertaking, Abingdon, Oxon. OX14 3EA (GB)
Record Number: 198910251 / Last updated on: 1994-12-01
Original language: en
Available languages: en