arXiv subjects

E. Stambulchik

Publications and source records attributed to E. Stambulchik.

5 recordsLinked to original sources

arXiv2026

Hot Spot Evolution Measured by High-Resolution X-Ray Spectroscopy at the National Ignition Facility

Evolution of the hot spot plasma conditions was measured using high-resolution x-ray spectroscopy at the National Ignition Facility (NIF). The capsules were filled with DD gas with trace levels of Kr, and had either a high-density-carbon (HDC) ablator or a tungsten (W)-doped HDC ablator. Time-resolved measurement of the Kr He$\beta$ spectra, absolutely calibrated by a simultaneous time-integrated measurement, allows inference of the electron density and temperature through observing Stark broadening and the relative intensities of dielectronic satellites. By matching the calculated hot spot emission using a collisional-radiative code to experimental observations, the hot spot size and areal density are determined. These advanced spectroscopy techniques further reveal the effect of W dopant in the ablator on the hot spot parameters for their improved implosion performance.

physics.plasm-ph↗

arXiv2025

Computer simulations of the Stark effect in the helium-beta complex of krypton in ICF conditions

There is an ongoing interest in using spectroscopy in inertial confinement fusion (ICF) experiments, where dopants such as krypton can provide vital information about the temperature and density of the imploding plasma. While the most advanced tools for calculating Stark profiles are computer simulation models (CSMs), their application to complex lineshapes under the extreme conditions of ICF experiments is computationally challenging. In this manuscript, we present results of several CSM realizations applied to the Stark shape of the krypton He-beta line and its satellites at ICF-relevant conditions (ne = 1e24 to 1e25 cm-3, Te = 3keV). We demonstrate that codes with the same underlying physics but different numerical approaches yield identical results and analyze the differences in the line profile caused by various physical effects.

physics.plasm-ph↗

arXiv2019

Review of the 10th Non-LTE Code Comparison Workshop

We report on the results of the 10th Non-LTE code comparison workshop, which was held at the University of San Diego campus November 28 through December 1, 2017. Non-equilibrium collisional-radiative models predict the electronic state populations and attendant emission and absorption characteristics of hot, dense matter and are used to help design and diagnose high-energy-density experiments. At this workshop, fifteen codes from eleven institutions contributed results for steady-state and time-dependent neon, aluminum, silicon, and chlorine cases relevant to a variety of high-density experimental and radiation-driven astrophysical systems. This report focuses on differences in the predictions from codes with different internal structure, completeness, density effects, and rate fidelity and the impact of those differences on hot, dense plasma diagnostics.

physics.plasm-ph↗

arXiv2018

Turbulent stagnation in a z-pinch plasma

The ion kinetic energy in a stagnating plasma was previously determined by Kroupp et al. (Kroupp et al., 2011), from Doppler-dominated lineshapes augmented by measurements of plasma properties and assuming a uniform-plasma model. Notably, the energy was found to be dominantly stored in hydrodynamic flow. Here, we advance a new description of this stagnation as supersonically turbulent. Such turbulence implies a non-uniform density distribution. We demonstrate how to re-analyze the spectroscopic data consistent with the turbulent picture, and show this leads to better concordance of the overconstrained spectroscopic measurements, while also substantially lowering the inferred mean density.

physics.plasm-ph↗

arXiv2007

Electric fields in plasmas under pulsed currents

Electric fields in a plasma that conducts a high-current pulse are measured as a function of time and space. The experiment is performed using a coaxial configuration, in which a current rising to 160 kA in 100 ns is conducted through a plasma that prefills the region between two coaxial electrodes. The electric field is determined using laser spectroscopy and line-shape analysis. Plasma doping allows for 3D spatially resolved measurements. The measured peak magnitude and propagation velocity of the electric field is found to match those of the Hall electric field, inferred from the magnetic-field front propagation measured previously.

physics.plasm-ph↗