TWO-ION MODE CONVERSION LAYERS IN JET
For ICRF heating of a plasma with a one-dimensional inhomogeneity, using the two-ion mode conversion of the fast wave, the mode conversion layer is defined by an algebraic expression, k**2-" = epsilON-perpendicular-omega**2/c**2, i.e. it is located where the perpendicular ion cyclotron resonance (related to the Alfven wave resonance in the low frequency limit) appears for the fast wave when the electron mass is neglected. In a Tokamak, on the other hand, epsilon-perpendicular and k-" varies considerably along the magnetic field, and the condition for mode conversion at a certain magnetic surface is determined by the eigenvalues of an ordinary differential equation along a poloidal intersection of the surface. In the present work, this equation is evaluated for magnetic surfaces in JET, run with D plasmas with a minority of T, and H plasmas with a minority of D or 3-He. The fundamental cyclotron resonance for the majority ions is chosen to be located on the outside of the plasma, while the surface epsilon-perpendicular = 0 passes close to the magnetic axis. For each magnetic surface the eigenvalues define a particle density, which has to equal the actual density for mode conversion to occur. The shape of the eigenfunctions and the implications for the coupling to antenna structures are discussed as well as the meaning of the surfaces n**2?R**2 = epsilON-perpendicular-omega**2/c**2, which are frequently referred to as mode conversion surfaces.
Bibliographic Reference: 4TH INTERNATIONAL SYMPOSIUM ON HEATING IN TOROIDAL PLASMAS, ROMA (ITALY), MARCH 21-28, 1984 VOL. I, PP. 451- 456 1478 P., VOL. I AND VOL. II, 1984 WRITE TO MONOTYPIA FRANCHI, ST. LUCIA + VIALE UMBRIA NO. 28, 06012 CITTA DI CASTELLO, PERUGIA (ITALY), USD 6
Record Number: 1989124028400 / Last updated on: 1987-01-01
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