Diagnosing the DARHT Electron Beam-Target Interaction and Hydrodynamic Expansion [Dissertation]

Abstract

The purpose of this dissertation is to provide a roadmap for spectral diagnostic development and modeling of the electron beam-target interaction at the Dual-Axis Radiographic Hydrodynamic Test (DARHT) facility. This is motivated by the current lack of detailed knowledge of the beamtarget interaction and the warm dense matter (WDM) generated during this process, along with the direct relevance to DARHT's main purpose in fulfilling its Stockpile Stewardship mission. Fully characterizing the beam-target interaction will improve the radiographic performance of the DARHT accelerators and can lead to a more advanced and optimized target design for minimizing the radiographic spot size. The phase space trajectory from cold metal to expanded plasma plume in an electron beam driven target is not known. Complicating this issue is the lack of validation of equation-of-state models in the WDM regime and under the vapor dome. The plasmas generated at DARHT span both regimes. Fully diagnosing this beam-target interaction can provide answers to many of these present unknowns. A critical part of solving these problems includes a full-scale, spectroscopic-quality radiation transport model to interpret the resulting spectroscopic measurements. This has been developed by linking together several codes, including atomic physics, radiation hydrodynamics, and radiation transport, and will continue to mature into the future.