Z-Pinch plasma instability experiments on the UM linear transformer driver

Summary form only given. Experiments are underway on the 1-MA, 100-kV MAIZE linear transformer driver (LTD) z-pinch experiment to explore the characterization and stabilization of the magneto-Rayleigh-Taylor (MRT) and electrothermal instabilities (ETI. Instability experiments at UM utilize 400 nm thick, planar Al foil loads and Al-backed Mylar foils. Theory has shown that axial magnetic fields and magnetic shear can reduce the growth rate of MRT2. To test effects of axial magnetic fields, pseudo-helical return current electrodes are substituted in place of planar electrodes. Instability growth is measured by sub-ps laser shadowgraphy viewing across the foil plasma, perpendicular to the current. The electrothermal instability (ETI) is an important earlytime effect on foil ablation experiments due to its ability to seed the destructive magneto-RayleighTaylor (MRT) instability. In tandem with the axial B-field work, additional foil compositions are being studied to determine ETI growth rates for varied material properties. Similarly, the effect of surface roughness on the resulting ETI is being investigated. Spectroscopic diagnostics are also under development on the UM LTD, which use Zeeman splitting to measure local magnetic fields and current distributions in z-pinch plasmas. Initial experiments, involving Al foils seeded with sodium, have measured Zeeman splitting towards the end of the current pulse using Na D lines and an ICCD coupled to a 0.75 m optical spectrograph. Several ion lines are currently being studied, such as Al III and C IV, as potential emission line candidates to measure the magnetic field along the current rise when the temperature is higher.