X-ray-line coincidence photopumping in a potassium-chlorine mixed plasma

Abstract

Exploiting the multiple long pulse capability and suite of x-ray diagnostics of the Orion laser, we have set out to explore line coincidence photopuming-the enhancement in population of an atomic level brought on by resonant absorption of x rays from a different emitting ion. Unlike previous work, the two ions are in the same plasma and so the experiment is an x-ray analog of the well-known Bowen resonance fluorescence mechanism that operates in astrophysical situations in the optical region. Our measurements have shown enhanced fluorescence in a chlorine plasma, attributable to line coincident photopumping from co-mixed potassium ions. To detect this relatively low signal-to-noise phenomenon, the data from multiple shots are combined, and the statistical method of bootstrapping is used to assign a confidence value to the measured enhancement, resulting in an estimate of the enhancement of 39 ± 16 18 % compared to the null case, where no pumping occurs. The experimental results have been compared to coupled radiation-transport and radiation hydrodynamics simulations using the CRETIN code together with the NYM radiation hydrodynamics model and agreement has been found, with the simulations also predicting modest enhancement.

Monte Carlo method for investigating population kinetics in non-local thermodynamic equilibrium plasmas

“…As described in section 1, the accuracy of atomic data and completeness of the number of atomic states have a significant impact on the correctness of the results. FAC is widely applied in astrophysical and laboratory-based research and demonstrates its excellent capabilities [34][35][36][37][38][39]. In FAC, the relativistic configuration interaction with independent particle basis wavefunctions is used to calculate the atomic structure.…”

Astronomy Domine: advancing science with a burning plasma

“…This could be used for a number of applications, but the one considered here is the possibility of pumping a line-coincidence scheme in another ion in a separate plasma. This work would be part of ongoing experimental work that explores in the laboratory mechanisms by which XUV and X-ray lasing can occur in plasmas (Hobbs et al 2020 [69]). The shortest wavelength laser to have been seen in an astrophysical setting is driven by line-coincidence photopumping (Letokhov and Johansson 2009 [70]).…”