Coherent x-ray radiation induced by high-current breakdown on a ferrite surface

We observe that at the initial stage of a high-current discharge, a low-divergence short x-ray pulse ($\approx\thinspace$$0.5^{\circ}$, $\thinspace$$500$ eV) with the energy of $\sim$$21\mu$J is formed over a ferrite surface, which propagates parallel to the surface in the anode direction. The high directionality of the radiation points to its coherent nature. We propose that the radiation is due to the short-lived magnetization of the ferrite surface excited by a high-power electromagnetic pulse. The radiation is coherent due to the equivalent excitation conditions for all emitters. The excitation pulse and the radiation it generates move at the same speed ($\sim$$c$). Thereby, the emitted waves propagating parallel to the ferrite surface are phase-matched, providing the high radiant intensity of the radiation

Scaling of X pinches from 1 MA to 6 MA.

This final report for Project 117863 summarizes progress made toward understanding how X-pinch load designs scale to high currents. The X-pinch load geometry was conceived in 1982 as a method to study the formation and properties of bright x-ray spots in z-pinch plasmas. X-pinch plasmas driven by 0.2 MA currents were found to have source sizes of 1 micron, temperatures >1 keV, lifetimes of 10-100 ps, and densities >0.1 times solid density. These conditions are believed to result from the direct magnetic compression of matter. Physical models that capture the behavior of 0.2 MA X pinches predict more extreme parameters at currents >1 MA. This project developed load designs for up to 6 MA on the SATURN facility and attempted to measure the resulting plasma parameters. Source sizes of 5-8 microns were observed in some cases along with evidence for high temperatures (several keV) and short time durations (<500 ps)