Experimental investigations of plasma erosion switches on the PITHON generator

Experiments on the behavior of plasma erosion switches have been performed on the PITHON generator in two geometries. Larger levels of current, switch area, and plasma density have been examined than have been reported previously. Currents as great as 1.5 MA have been switched to a downstream load. The available switch area has been increased from 1,000 cm² to 2,900 cm² and the maximum useful switch plasma density increased from ∼ 1 × 10¹³/cm³ to ∼ 2.5 × 10¹³/cm³. The switch current, voltage, power, and energy have been found to increase with plasma density. Analysis of the 1,000 cm² switch data indicates that the dissipation of inductively stored energy by the switch increases with the magnitude of the inductance downstream of the switch. Studies of the scaling of switch current and power with switch voltage suggest that the opening mechanism is dominated by magnetic cut-off of electron flow. The general agreement of the experimental switch behavior with magnetic insulation theory suggests that numerical modeling of the switch may be possible.