Lower Hybrid Heating in the Wega Tokamak

Lower hybrid wave heating in the Octopole tokamak

“…This term was only about 20% of the first term which represents the absorbed RF power determined from measured increases in plasma density and temperature. With respect to the sensitivity of the computed values of P R F to the model (2)(3), we note that any atomic process, whether on H£ or impurities, will imply P LO ss a n e and that about 80% of the computed value of P R F comes from the observed density rise. The temperature scaling in (2-3) may vary from T°t o T| with only 20% changes in the computed values ofP R F .…”

“…The development of lower hybrid wave heating of tokamak plasmas has been pursued vigorously since the technology required for reactor application largely exists [1 ]. Most experiments have concentrated on ion heating with OJ = CJ L H [2][3][4][5][6]. More recent experiments [7][8][9], including this experiment, have sought electron heating by Landau damping with co several times greater than CO L H a n d wave phase speeds somewhat above the electron thermal speed.…”

High-frequency heating experiments in PETULA and WEGA tokamaks

“…5). These results were confirmed in the upgraded WEGA (Bj = 2.2 T, I p = 80 kA) where the fourwaveguide grills used showed the importance of the wave spectrum for the heating [13]. First results of current generation were obtained at low density ( n e < 10 13 cm" 3 ) with a travelling wave.…”

Experimental studies on current drive by slow lower-hybrid waves

“…It is very important to check current generation by a travelling wave in a simple torus configuration without plasma current. A low-density, current-free plasma (n e « 10 11 cm" 3 , T e * 4 eV) was produced with a 2.45 GHz microwave by electron cyclotron resonance. The direction of the RF-driven current was found to be consistent with that of the wave propagation.…”

“…Applications of radio-frequency (RF) power near the lower-hybrid resonance frequency are quite attractive for the heating and control of tokamak plasmas. Efforts have been directed mainly towards ion heating [1][2][3], but recent experiments are devoted to electron heating [1, 4 -6 ] and current drive [7][8][9][10][11][12][13]. The latter offers the prospect of the realization of a steady-state tokamak reactor [14].…”