Results of the Inner Electrode Modification on the ZaP Flow Z-Pinch

Abstract

The ZaP Flow Z-Pinch is a basic plasma physics experiment that uses sheared flows to stabilize an otherwise unstable configuration. The inner electrode is replaced with a larger version (15 cm diameter presently versus 10 cm previously). The goal of this modification is to increase temperature through increased adiabatic compression and to allow greater flexibility of neutral-gas injection through a greater number of gas-puff valves. Results are presented regarding the effect of neutral-gas injection characteristics and charge voltage on pinch stability. Increasing capacitor bank voltage and mass of gas injected increases stability and proximity to the machine axis. A four-chord HeNe interferometer is used to determine density at z = 0 cm and total temperature using magnetic field information from the z = 0 azimuthal array of magnetic probes. Total temperatures of 100–150 eV and densities of 2–3 × 10²² m⁻³ are calculated; temperatures are consistent with measured electron and ion temperatures.