Ponderomotive force effects on slow-wave coupling

Abstract

Localized plasma density depressions are observed to form near a multi-ring slow-wave structure when the value of the nonlinearity parameter, s = ω2pe‖Ez‖2/8πω2nκT, is of order unity. Consequent changes in the wave propagation and coupling efficiency are reported. For large enough values of s, the coupling efficiency may be reduced by 50% from the linear value.

Study of plasma impedance for electrostatic waves coupling

“…To launch electrostatic waves many types of slow-wave antenna can be utilized: loops [IO], waveguide or metallic blades [2,11]. In our model we consider a periodic 074I-3335/95/070763+09$19SO @ 1995 IOP Publishing Ltd structure composed of metallic blades [I].…”

“…We calculate the resistive part of the impedance as the ratio between the instantaneous voltage and the instantaneous current Z = V / l , where I = dq/dt = ioq and o is the wave frequency. To find the total charge q we apply Gauss' law calculating the flux of the radial component Er of the electric field entering the plasma from the antenna (the other electric field components d o not contribute to the total flux) [2]:…”

Response of the scrape-off layer plasma in the Frascati Tokamak to lower hybrid heating

“…The ponderomotive forces in the LH frequency range have been extensively studied [8,9]. They are also believed to be responsible for the non-local density reduction observed in experiments on small laboratory plasmas [10,11]. A reduction in density of the SOL plasma has been observed also in ASDEX [12] and WEGA [13] after injection of LH power.…”