The effect of lower hybrid instabilities on plasma confinement in fiber Z pinches

Lower hybrid microinstabilities are found to have an adverse effect upon radial pressure balance in fiber Z-pinch plasmas. Magnetohydrodynamic simulations show that the anomalous resistivity resulting from these microinstabilities causes the formation of a low-density, highly resistive, coronal plasma. This corona penetrates farther and at a faster rate into the plasma for higher pinch currents and lower line densities. If the resistive corona penetrates to the pinch axis then continuous, global expansion ensues. Simulations of the ionization phase of both carbon and hydrogen fiber Z-pinch experiments show substantial expansion of the plasma column due to these microinstabilities during this phase. These microinstabilities also make radiative collapse more difficult to achieve, particularly in low line density hydrogen pinches. This reduces the peak density that can be achieved by this process.