X-ray line coincidence photopumping in a solar flare
Monthly Notices of the Royal Astronomical Society Oxford University Press 474:3 (2017) 3782-3786
Abstract:
Line coincidence photopumping is a process where the electrons of an atomic or molecular species are radiatively excited through the absorption of line emission from another species at a coincident wavelength. There are many instances of line coincidence photopumping in astrophysical sources at optical and ultraviolet wavelengths, with the most famous example being Bowen fluorescence (pumping of O III 303.80 Å by He II), but none to our knowledge in X-rays. However, here we report on a scheme where a He-like line of Ne IX at 11.000 Å is photopumped by He-like Na X at 11.003 Å, which predicts significant intensity enhancement in the Ne IX 82.76 Å transition under physical conditions found in solar flare plasmas. A comparison of our theoretical models with published X-ray observations of a solar flare obtained during a rocket flight provides evidence for line enhancement, with the measured degree of enhancement being consistent with that expected from theory, a truly surprising result. Observations of this enhancement during flares on stars other than the Sun would provide a powerful new diagnostic tool for determining the sizes of flare loops in these distant, spatially unresolved, astronomical sources.Modelling K shell spectra from short pulse heated buried microdot targets
HIGH ENERGY DENSITY PHYSICS 23 (2017) 178-183
Measurements of plasma spectra from hot dense elements and mixtures at conditions relevant to the solar radiative zone.
ATOMIC PROCESSES IN PLASMAS (APIP 2016) 1811 (2017)
Particle Interactions in High-Temperature Plasmas Supervisor's Foreword
Chapter in PARTICLE INTERACTIONS IN HIGH-TEMPERATURE PLASMAS, (2017) V-V
Sherlock et al. Reply
Physical Review Letters American Physical Society 116 (2016) 159502