Conceptual study of a reflector waveguide array for launching lower hybrid waves in reactor grade plasmas
A new concept, the reflector waveguide array, is proposed to improve and simplify the design of continuous wave lower hybrid (LH) launchers for steady state reactor applications. Mechanical robustness of the antenna and efficient heat removal are provided by a thick wall waveguide structure that can accommodate a large number of cooling ducts. The plasma facing mouthpiece could be made of the same material as the reactor first wall and could be easily replaceable through remote handling. In order to compensate for the increased horizontal distance between adjacent waveguides, the front ends of the thick septa are grooved to form short passive waveguides that acta as reflectors between the radiofrequency powered waveguides (drivers). For an adequate phasing between the active waveguides, the total electric field at the reflector waveguide apertures varies coherently with the one in the drivers to launch a highly directional slow wave. It is shown that the coupling properties of such an array and the directivity of the radiated power spectrum are similar to those of present day launchers. Their dependences upon the depth of the reflector waveguides, and the electron density and its gradient are investigated. The effect of changing the phase between the drivers is also studied.
Bibliographic Reference: Article : Nuclear Fusion, Vol. 35 (1995), No. 10, pp. 1213-1223
Record Number: 199512137 / Last updated on: 1996-01-15
Original language: en
Available languages: en