Exploratory investigation of the HIPPO gas-jet target fluid dynamic properties

TL;DR

This study explores the fluid dynamic properties of the HIPPO gas-jet target using CFD simulations to enable faster characterization methods, revealing sensitivity to design parameters and suggesting future improvements for nuclear reaction experiments.

Contribution

First application of CFD simulations to characterize HIPPO gas-jet target, demonstrating potential for rapid assessment and highlighting key design sensitivities.

Findings

CFD simulations match elastic scattering measurements

Gas-jet density is highly sensitive to nozzle geometry and pressure

Three-dimensional simulations are needed for better predictive accuracy

Abstract

In order to optimize the performance of gas-jet targets for future nuclear reaction measurements, a detailed understanding of the dependence of the gas-jet properties on experiment design parameters is required. Common methods of gas-jet characterization rely on measuring the effective thickness using nuclear elastic scattering and energy loss techniques; however, these tests are time intensive and limit the range of design modifications which can be explored to improve the properties of the jet as a nuclear reaction target. Thus, a more rapid jet-characterization method is desired. We performed the first steps towards characterizing the gas-jet density distribution of the HIPPO gas-jet target at the University of Notre Dame's Nuclear Science Laboratory by reproducing results from $^{20}\rm{Ne}(\alpha,\alpha)^{20}\rm{Ne}$ elastic scattering measurements with computational fluid dynamics (CFD) simulations performed with the state-of-the-art CFD software ANSYS Fluent. We find a strong sensitivity to experimental design parameters of the gas-jet target, such as the jet nozzle geometry and ambient pressure of the target chamber. We argue that improved predictive power will require moving to three-dimensional simulations and additional benchmarking with experimental data.