9412916 Rocca Important existing and emerging applications require the development of efficient and compact sources of x-ray radiation. We propose an international collaboration to combine experimental and theoretical efforts in the study of the hot plasma channels produced by fast capillary discharges for the development of efficient sources of both coherent and incoherent soft x-ray radiation. The proposed research is motivated by results of recent experiments conducted at Colorado State University, that confirm that very fast excitation of capillary channels with current risetimes of approximately 10ns can generate dense plasma columns of small diameter with electron temperatures of a few hundred eV utilizing currents that are more than an order of magnitude smaller than those employed to obtain hot plasmas in Terawatt pulse power machines. Results include the observation of emission from the 3p-3s laser candidate transitions of neon-like calcium in 1.5 -2.5mm diameter capillaries at currents as low as 40kA. Such capability for efficiently generating plasma columns of small (200um) diameter by direct discharge excitation could provide a new route towards compact and efficient soft x-ray lasers. Also, the direct transfer of electrically stored energy into reproducible hot capillary plasmas of small diameter and could result in a cost efficient incoherent x-ray source. The proposed cooperative research will combine capillary discharge experiments conducted at Colorado State University with a detailed theoretical analysis of the radiative properties of capillary discharge plasmas, which will be based on elaborate magnetohydrodynamic and radiation transport codes developed at the Lebedev Physics Institute. The comparison of spatially and time resolved soft x-ray spectra from capillary plasmas operating in a new fast discharge regime with state of the art MHD/atomic physics calculations is expected to provide an increased understanding of these plasmas and the necessary guidance for their development into efficient practical sources of coherent and incoherent soft x-ray radiation.
