Study of X-ray photoionized Fe plasma and comparisons with astrophysical modeling codes

Abstract

The charge state distributions of Fe, Na and F are determined in a photoionized laboratory plasma using high resolution x-ray spectroscopy. Independent measurements of the density and radiation flux indicate the ionization parameter ξ in the plasma reaches values ξ= 20-25 erg cm s −1 under near steady-state conditions. A curve-of-growth analysis, which includes the effects of velocity gradients in a onedimensional expanding plasma, fits the observed line opacities. Absorption lines are tabulated in the wavelength region 8-17Å. Initial comparisons with a number of astrophysical x-ray photoionization models show reasonable agreement.

Experimental astrophysics with high power lasers andZpinches

“…GALAXY is a collisional-radiative code that calculates the steady-state ionization balance within the plasma, given density, temperature, and incident radiation field as input ͑Rose, 1998; Foord et al, 2004Foord et al, , 2006Rose et al, 2004͒. Collisional and radiative excitation and ionization as well as autoionization and all reverse processes are included.…”

The effect of a radiation field on excitation and ionisation in non-LTE high energy density plasmas

“…There it became evident that radiation transport through the sample of interest may need to be taken into account to arrive at agreement between experiment and theory. Experiments in which the broadband photopump arises from a collapsed Z-pinch have been described by Bailey et al [5] and Foord et al [12,13]. Foord et al [12,13] show comparison between the experimentally measured ionisation distribution and the predictions of a number of models including CLOUDY and GALAXY.…”

“…A nitrogen plasma with a photoionisation parameter x w 10 erg cm s À1 has recently been produced in a laser-driven hohlraum target [36] but to obtain the most extreme values of the photoionisation parameter in the laboratory, target designs are being developed that will use the largest highpower lasers available (such as the National Ignition Facility). These Comparison between distribution of ionisation fraction for Fe measured in the Z-machine experiment [12,13] with the model CLOUDY [9,12] and the average-atom model NIMP [31]. The calculation for NIMP not including a radiation field is included to show its effect on the distribution of ionisation.…”

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).…”