Non Linear Effects Produced by Electrostatic Waves in a Magnetized Plasma

Some non-linear phenomena, like ponderomotive effects and parametric decays, produced by high power electrostatic waves in a magnetized low density plasma, have been investigated experimentally. The injection of high power electrostatic waves into a plasma causes ponderomotive forces arise. Their action primarily gives rise to a plasma density depletion in front of the launching system and subsequently affects both the wave injection and propagation, producing cavitons. Beside these effects, RF power produces parametric decays which are also responsible of an edge electron heating. Above mentioned phenomena were studied in the range of low frequencies (1 t 100 MHz), in conditions of high (n, = 1011 cm-3) and low (n, = lo9 cm-3) density, analyzing the modifications of the electron density and temperature profiles, the shape of e.s. waves's electric field and the spectrum of the detected signals. 1. GENERAL DEDUCTION OF A PONDEROMOTIVE FORCE DENSITY To interpret accurately the ponderomotive effects, it is necessary to include the ponderomotive force in the fluid description of plasmas by calculating the generalized force density term V . (nmvw) in a non-collisional momentum balance equation 3 nmv) + v . ( n m w ) + v . j~ + n e ( ~ + lv x B ) = o at ( C -