Towards recombination pumped H-like N X-Ray laser

Abstract

Summary form only given. The recombination pumping scheme for soft X-Ray lasers has better energy scaling, than the collisional-excitation pumping scheme. Implementation of an H-like 3 →2 Nitrogen recombination laser, at λ~13.4 nm requires initial conditions of at least 50% fully stripped Nitrogen, kTe~140eV and ne~10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">20</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> . In order to reach population inversion, the plasma cooling to below 60eV should be faster than the typical three body recombination time. The goal of this study is achieving the required plasma conditions using a capillary discharge Z Pinch apparatus. The experimental setup includes an alumina capillary coupled to a pulsed power generator of ~60 kA peak current, with a quarter-period of 60 ns. Various diagnostic techniques are applied to measure the plasma conditions, including X-Ray diode, time-resolved pinhole imaging and time-resolved spectrometry coupled to a multi-ion collisional-radiative atomic model. The current study aims at seeking the optimum plasma conditions through measurement in different capillary radii and different initial gas pressures. The results show a fast cooling period to below 60eV, demonstrating the feasibility of capillary discharge lasers.