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

Journal article

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.

Authors: Hobbs, LMR; Burridge, D; Hill, MP; Hoarty, DJ; Brown, CRD

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Physical Society
• Journal: Physical Review A
• Volume: 101
• Issue: 5
• Article number: 53431
• Publication date: 2020-05-21
• Acceptance date: 2020-04-28
• DOI: 10.1103/physreva.101.053431
• EISSN: 2469-9934
• ISSN: 2469-9926
• Language: English
• Keywords: FFR