X-ray emission from a high-atomic-number Z-pinch plasma created from compact wire arrays

Thermal and nonthermal x-ray emission from the implosion of compact tungsten wire arrays in 5-MA Saturn discharges is reported. The timing of multiple implosions and the thermal x-ray spectra (l to 10 ke V) agree with 2D radiation-hydrocode simulations. Nonthermal x-ray emission (l0 to 100 ke V) correlates with pinch spots distributed along the z-axis. The similarities of the measured non thermal spectrum, yield, and pinch-spot emission with those of 0.8-MA, single-exploded-wire discharges on Gamble-II suggest a common nonthermal-production mechanism. Nonthemal x-ray yields are lower than expected from current scaling of Gamble II results, suggesting that implosion geometries are not as efficient as single-wire geometries for non thermal x-ray production. The instabilities, azimuthal asymmetries, and inferred multiple implosions that accompany the implosion geometry lead to larger, more irregular pinch spots, a likely reason for reduced non thermal efficiency. A model for non thermal-electron acceleration across magnetic fields in highly-collisional, high-atomic-number plasmas combined with ID hydrocode simulations of Saturn compact loads predicts weak nonthermal x-ray emission.