Pinhole camera imaging of an ablative capillary discharge investigated for the development of a soft X-ray laser

Summary form only given. End-on images of an ablative capillary discharge have been obtained using a time resolved pinhole camera This experiment was motivated by the feasibility study of a soft X-ray laser in a highly ionized carbon plasma created by electrical discharges. Such laser effects have already been observed in laser pumped X-ray laser experiments. The population inversion can be obtained by a collisional recombination scheme, which is favored by a rapid cooling of the fully stripped carbon plasma. In our experiment, the plasma was created by injecting a high current pulse of several tens of kA in 100 ns into a 1 mm diameter capillary initially under vacuum. It was composed of highly ionized carbon and stripped hydrogen provided by the polyethylene capillary wall. Soft X-ray production could be spatially localized by analyzing images obtained by means of a 0.1 /spl mu/m polyimide filter, which was installed between the discharge and the camera. The polyimide filter had a good transmission for soft X-rays from the 10-20 nm wavelength range.