Density gradient drift instabilities: Oblique propagation at zero beta

The linear Vlasov dispersion relation for electrostatic instabilities driven by a cross field current due to a density gradient in a unidirectional magnetic field is examined in the local approximation. Both electrons and ions are taken as magnetized, and propagation is in the plane defined by the drift velocity and the magnetic field. Three instabilities are studied and compared: the lower hybrid drift, ion cyclotron drift, and the universal drift instability. Thresholds and properties at oblique propagation are studied for a wide range of drift speeds and Te/Ti ratios. Each of these modes propagates at sufficiently oblique angles to prevent stabilization due to finite length in typical linear theta pinches greater than several hundred ion gyroradii in length.