Current driven weak ion acoustic turbulence in a magnetized plasma

The current driven ion acoustic instability has been studied in a quiescent magnetized argon plasma for electron densities in the range from 1010 to 1011 cm-3, an electron temperature T/sub e/ of 2.2 eV, an electron-ion temperature ratio T/sub e//T/sub i/ of 15, a homogeneous magnetic field of 400 G, and neutral gas pressures in the range from 1 x 10-3 to 5 x 10-3 mm Hg. Coulomb collisions are important for these experimental conditions. The instability occurs for dc currents in the range from 100 to 600 mA. The saturation appears to be explained by electron trapping. The nature of the instability is identified from measurements of the cross power density spectrum and the characteristic parameters like electron drift velocity, collisional damping, electron temperature, and electron-ion temperature ratio are determined precisely from an observation of low frequency ion acoustic test waves using an unperturbative method of microwave interometry