Experimental Observation of Drift Instabilities in a Collisionless Plasma

Pressure-gradient—driven drift waves have been identified in a collisionless ($n_0={10}^{10}$ ${\mathrm{cm}}^{-3\mathrm{}}$, $T_e=10\mathrm{}$ eV), 5.4-m-long, hydrogen plasma. Measurements show large but finite parallel wavelengths and short transverse wavelengths as predicted by the theory. For these wavelengths, computations give the maximum linear theoretical growth rate.