Investigation of X-ray lasing in a capillary discharge

Using a new technique of an induced MHD instability in a capillary made of polyacetal we observed an intense spike (signal) of the Balmer-a line of C VI at 18.22 nm during the second half cycle of the discharge. The spike is identified as Amplified Spontaneous Emission (ASE), and enhancements are derived for capillaries of lengths between 15 and 50 mm. This ASE is explained as a result of charge exchange between plasma ions produced in the neck of the MHD instability, where m=0, and low temperature ions which are present in the same plasma column. Different wavelengths of carbon and oxygen were scanned and no spike was seen with the exception of the one mentioned above. The amplitude of the spike was increased when a plane multilayer mirror of Mo/Si was introduced and a gain of 12 cm(-1) was obtained.