X-ray lasing as a result of an induced instability in an ablative capillary discharge

We report lasing of the CVI Balmer-alpha line at 18.22 nm using the new tec hnique of an induced MHD instability in an ablative capillary discharge. A large spike of this line during the second half-cycle of the discharge is o bserved. The spike is identified as amplified spontaneous emission (ASE), a nd enhancements are derived for capillaries of lengths between 15 and 50 mm . We explain the ASE as a result of charge exchange processes which occur b etween ions produced in the neck of the MHD instability and low temperature ions present in the same plasma column. To emphasize this instability, we implemented a new method by using a straight capillary with a waved structu re imprinted inside. The results are encouraging and an exponential gain le ngth is achieved with GL = 4.5 for a 40 mm length capillary. Other evidence to support the observation is realised when a plane multilayer mirror with reflectivity < 30% is introduced resulting in amplification.