Title :
The design of a tapered dimple-type mode converter/launcher for high-power gyrotrons
Author :
Hirata, Yosuke ; Mitsunaka, Y. ; Hayashi, K. ; Itoh, Y. ; Sakamoto, K. ; Imai, T.
Author_Institution :
Power & Ind. Syst. R&D Center, Toshiba Corp., Kawasaki, Japan
fDate :
2/1/2003 12:00:00 AM
Abstract :
This paper presents the design method for a gyrotron-dimple-type mode converter that is axially up-tapered to prevent inside oscillation. In this up-tapered converter, the propagation constant of the traveling TE modes varies axially since the mean radius grows in the axial direction, requiring a new formulation of the mode coupling in the converter. In this paper, the axial variation of the helix pitch that describes the TE mode propagation is discussed first. Then, the coupling coefficients between TE modes are analytically derived, with which a trial design of a linearly tapered converter is made for a 170-GHz gyrotron.
Keywords :
Tokamak devices; gyrotrons; millimetre wave devices; waveguide components; ECH; ITER; TE mode propagation; analytical formulation; axial direction; axial variation; axially up-tapered mode converter; coupling coefficients; cutoff condition; design method; helix pitch; high-power gyrotrons; inside oscillation prevention; international thermonuclear experimental reactor; mean radius; mode coupling formulation; propagation constant; radius change; tapered converter; tapered dimple-type mode converter/launcher; traveling TE modes; Couplings; Design methodology; Diffraction; Gyrotrons; Optical reflection; Optical surface waves; Optical waveguides; Propagation constant; Surface waves; Tellurium;
Journal_Title :
Plasma Science, IEEE Transactions on
DOI :
10.1109/TPS.2003.808864
