The Role of Helium on Ejecta Production in Copper.

Saryu Fensin,Jeremy Payton,Daniel Martinez,David Jones,Calvin Lear

doi:10.3390/ma13061270

Abstract

The effect of helium (He) concentration on ejecta production in OFHC-Copper was investigated using Richtmyer–Meshkov Instability (RMI) experiments. The experiments involved complex samples with periodic surface perturbations machined onto the surface. Each of the four target was implanted with a unique helium concentration that varied from 0 to 4000 appm. The perturbation’s wavelengths were m, and their amplitudes were varied to determine the wavenumber amplitude product at which ejecta production beganfor Cu with and without He. The velocity and mass of the ejecta produced was quantified using Photon Doppler Velocimetry (PDV) and Lithium-Niobate (LN) pins, respectively. Our results show that there was an increase of 30% in the velocity at which the ejecta cloud was traveling in Copper with 4000 appm as compared to its unimplanted counterpart. Our work also shows that there was a finer cloud of ejecta particles that was not detected by the PDV probes but was detected by the early arrival of a “signal” at the LN pins. While the LN pins were not able to successfully quantify the mass produced due to it being in the solid state, they did provide information on timing. Our results show that ejecta was produced for a longer time in the 4000 appm copper.

Highlights

It is well known that when a shock wave in a material reaches a free surface, it can lead to ejection of particles from the surface [1,2,3]; this process and the launched material is referred to as ejecta.Over the last few decades there has been a body of research to understand the relationship between the total ejected mass and parameters associated with the free surface itself
We investigate the effect of helium concentration on ejecta production through the use of Richtmyer–Meshkov Instability experiments
We decided to focus on discussing results from a kh of 0.9 in this paper, as the focus of this work is on the effect of helium on ejecta production rather than the effect of kh on ejecta production

Summary

Introduction

It is well known that when a shock wave in a material reaches a free surface, it can lead to ejection of particles from the surface [1,2,3]; this process and the launched material is referred to as ejecta.Over the last few decades there has been a body of research to understand the relationship between the total ejected mass and parameters associated with the free surface itself. More recent work by Zellner et al [7] to study the role of surfaces prepared with different processes and final finishes on ejecta production in aluminum 1100 and Sn showed a similar sensitivity of total ejected mass and the density distribution of ejected fragments to the final finish of the surface. This has been confirmed with numerous molecular dynamics simulations that suggest surface roughness to be the Materials 2020, 13, 1270; doi:10.3390/ma13061270 www.mdpi.com/journal/materials

Objectives

Methods

Results

Conclusion