A Magnetic Annular Arc

Abstract
The performance characteristics of an annular arc configuration under the influence of a magnetic field were experimentally analyzed, particularly with respect to the effects of tensor conductivity and jxB body forces. In this device the plasma conditions are such that the electrical conductivity is insufficient to prevent the diffusion of the plasma through the magnetic field, i.e., the magnetic Reynolds number was small. Experiments were conducted with this device using He and Ar at power levels up to 50 kw, magnetic field strengths to 10,000 gauss and particle densities of the order of 10 to the 16th power/cu cm to 10 the 17th power/cu cm. The electron gyro radius was smaller than the electron mean free path. The impedance of the arc in helium was found to vary linearly with gyro frequency and time between collisions for electrons. The existence of a circulating azimuthal Hall current was also demonstrated. A yaw probe was employed to measure the angle of the flow due to the jxB Lorentz forces. A good agreement was found between the measured rotation in argon and the predicted value obtained from momentum considerations.