Production of photoionized plasmas in the laboratory with x-ray line radiation

Abstract

In this paper we report the experimental implementation of a theoretically proposed technique for creating a photoionized plasma in the laboratory using x-ray line radiation. Using a Sn laser plasma to irradiate an Ar gas target, the photoionization parameter, ξ=4πF/N_{e}, reached values of order 50ergcms^{-1}, where F is the radiation flux in ergcm^{-2}s^{-1}. The significance of this is that this technique allows us to mimic effective spectral radiation temperatures in excess of 1 keV. We show that our plasma starts to be collisionally dominated before the peak of the x-ray drive. However, the technique is extendable to higher-energy laser systems to create plasmas with parameters relevant to benchmarking codes used to model astrophysical objects.

L-shell X-ray conversion yields for laser-irradiated tin and silver foils

“…This provided a region where the background due to crystal/filter fluorescence and hard X-rays not diffracted from the crystal would be present, and hence allow a background subtraction from the data. The L-shell Sn spectrum from the experiment has been spectrally calibrated by the use of spectra from previous work in White et al [6]. We calibrated the L-shell Ag spectra using a calibration shot with KBr, in which the He-α line group (1s 2 -1s2p 1 P and 3 P lines and Li-like satellites) was recorded.…”

“…Over the past five decades, various types of X-ray sources have been produced by irradiating solid and gaseous targets with high power lasers in controlled laboratory settings. These X-ray sources are useful in research fields such as inertial-confinement fusion, plasma diagnostics (scattering, radiography, fast ignition and absorption spectroscopy) [1,2,3,4], laboratory astrophysics [5,6] and warm dense matter. Many experiments have been performed to study multi-keV X-ray sources in which various elements have been investigated for K-shell [7,8,9,10], L-shell [11,12] and M-shell [13] emission.…”

“…(b) A typical pulse shape for the incident laser beams recorded with an optical streak camera. side of the target foil can be very useful, for example, when employing this X-ray emission to photoionise or volumetrically heat a gas or foil target [6,12].…”

Multiple photoionization for the K shell in the Fe atom

“…The photoionized plasmas were observed in diffuse sources (stellar or interstellar gas, supernova remnants) and around compact objects (black holes, neutron stars) (see, e.g., Watanabe et al 2006;Temple et al 2020;Schulz et al 2020). Lasers or magnetic pinch machines also provided ideal opportunities to study photoionized plasmas in laboratories (see, e.g., Foord et al 2006;Hall et al 2014;Saber et al 2017;Loisel et al 2017;White et al 2018).…”

Multiple photoionization cross sections for Fe2+ K shell

“…The photoionized plasmas were identified in stellar gas, supernova remnants, around compact objects such as black holes and neutron stars (see, e.g., Watanabe et al 2006;Lee et al 2009;Kallman et al 2019). Furthermore, laboratorygenerated photoionized plasmas were studied using power lasers and fast magnetic pinch machines (see, e.g., Foord et al 2006;Hall et al 2014;White et al 2018).…”