Low-frequency instabilities in a laboratory magnetized plasma column

A detailed analysis of the phase velocity of unstable low-frequency waves is performed in a laboratory magnetized plasma column. The measurement of the radial profiles of the density, electron temperature and plasma potential allows to determine the radial profile of the electric drift velocity and electron diamagnetic drift for increasing values of the magnetic field. In the case of a large diameter plasma column, only diamagnetic drift waves without ExB Doppler shift occur. On the other hand, in the case of a restricted diameter plasma column, the radial electric field induces a rotation of the plasma column. At low magnetic field the recorded unstable waves are in that case flute modes propagating azimuthally at the ExB drift velocity. (C) 2004 American Institute of Physics.