Modeling of capillary Z-pinch recombination pumping of boron extreme ultraviolet laser

Abstract

Computer modeling of fast capillary discharge is performed to investigate a new laser active medium created by excited hydrogenlike boron ions leading to lasing at 26.23 nm. Recombination excitation of the boron ions is expected in the undercooled pinching plasma created during the expansion phase of the pinch. Plasma dynamics is described by the magnetohydrodynamic code NPINCH and the plasma ion kinetics is evaluated according to the FLY code. Results of simulations for capillary filled with boron are reported and compared with previous results achieved for nitrogen filled capillary. In both cases, the same nonablative capillary with radius of 1.6 mm is presumed and the current pulse with 50 kA peak value and 10 12 A s −1 current slope are taken into account. Evaluated pressure optimized gains are 1.04 and 0.11 cm −1 are found for boron and nitrogen filled capillary, respectively. Capillary wall ablation is then also assayed.

Effect of autoionizing states with a high-lying spectator electron on population inversion of nitrogen plasma in recombining phase

“…In the study by Vrba et al [6], the kinetic code FLY [10] was used. However, doubly excited states whose outermost electron is bound in a higher orbital are not considered.…”

“…Although a related experiment has been performed and a pulse waveform shaping is designed for the rapid cooling, there is no lasing [5]. A related magnetohydrodynamic (MHD) simulation using an atomic population kinetics code for Z-pinch recombination pumping was performed [6]. In the research, a recommended pressure is estimated and the maximum gain of 0.11 cm −1 is obtained.…”

“…Those states can be implicitly included in an atomic model proposed by Fujimoto et al [7]. processes are not considered in the study done by Vrba et al [6]. In a recombining plasma scheme, the DL deexcitation may play an important role to create the population inversion.…”

A Study of Coherent Radiation Generated in an Ablative Capillary Discharge

“…All the simulations presented here were obtained under the presumption of wall ablation. The plasma-wall interaction was modeled by considering the evaporated material from the wall as a cold neutral gas of high density and sufficiently high total mass [6].…”

“…This parameter has not been dealt with in our research. In the past, some low-Z elements were studied as possible sources of coherent radiation for recombination pumping in capillary discharges [6,10,11]. Nitrogen and carbon were selected as the best adepts for our investigation in an ablated capillary.…”