Creation of a single-shot micrometer-size X-ray source in X-pinch discharge energized by very fast capacitor bank

Among dense discharge plasmas, X-pinches are well known for providing a point-like x-ray source in the keV region and have been applied for backlighting of dense plasmas. An X-pinch is commonly energized by a fast HV generator terminated by a pulse forming line, because capacitor bank based generators are slow and fail to produce a unique x-ray peak. We have used an original approach with the fast and compact generator PIAF, a low impedance machine (0.12 Ohm) based on a 1 kJ capacitor bank and an extremely low inductance design (16 nH). It is then possible to drive a 250 kA current peaking in less than 200 ns into a six nH inductive load. We will report on experimental study of X-ray source radiated from the high energy density plasma created at the crossing point of two or four wires (Mo, W) of thin diameter ( 18 to 25 micrometers). We used multi-filtered pinhole imaging and large aperture penumbral analysis to get time-integrated information in the 1-5 keV region. In some configurations, a unique source is observed with size as small as 10 micrometers. Using vacuum x-ray diodes and p-i-n photo-detectors, we are able to identify a single peak during less than 1.5 ns. One estimates a radiation yield of about 250-500 mJ in the softer range (<700 eV) and 50-100 mJ in the harder one (<1 keV). Preliminary results of time-integrated spectroscopy will be discussed too.