Date of Graduation
Eberly College of Arts and Sciences
Physics and Astronomy
Temperature and density measurements of plasmas are important for understanding various phenomena. For example, equations of state, most scaling arguments for Inertial Confinement Fusion and laboratory astrophysics all rely upon accurate knowledge of temperature and density. Spectroscopy is a non-invasive technique to measure these quantities. In this work we establish a new spectroscopic technique by using it to determine temperature. We also compare and contrast the capability of two codes, PrismSPECT and ATOMIC, to infer electron density from experimentally acquired spectra via Stark broadening.
We compare and contrast the capability of isoelectronic line ratios and inter-stage line ratios in an absorption spectra to determine electron temperature of a plasma in Local Thermodynamic Equilibrium. The isoelectronic line ratio method has been used previously for experimentally required emission spectra. Stark broadening is often used with a tracer element to diagnose a plasma’s electron density. Our objective is testing quantitatively how well Stark broadening models can predict the plasma density from multiple elements within the same plasma, and whether this is done self-consistently.
We measure a transmission spectrum through a ~0.4 $\mu$m Mg-NaF multi-layered foil, tamped with a uniform layer of CH. We use X-rays from the Z facility at Sandia for heating and backlighting. Measurements were acquired in the 7-15$\AA$ range. We found that temperatures inferred from isoelectronic line ratios agree with temperatures inferred from inter-stage line ratios within error. We also found that densities inferred from different elements do not agree when using PrismSPECT, but do agree when using ATOMIC.
Lane, Theodore Scott, "Evaluation of X-ray Spectroscopic Techniques for Determining Temperature and Density in Plasmas" (2019). Graduate Theses, Dissertations, and Problem Reports. 4018.