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Title: Use of Z-Pinch Techniques for Equation of State Applications

Abstract

A principal goal of the shock physics program at Sandia is to establish a capability to make accurate equation of state (EOS) measurements on the Z pulsed radiation source. The Z accelerator is a source of intense x-ray radiation, which can be used to drive ablative shocks for EOS studies. With this source, ablative multi shocks can be produced to study materials over the range of interest to both weapons and ICF physics programs. In developing the capability to diagnose these types of studies on Z, techniques commonly used in conventional impact generated experimental were implemented. The primary diagnostic presently being used for this work is velocity interferometry, VISAR, which not only provides Hugoniot particle velocity measurements, but also measurements of non-shock EOS measurements, such as isentropic compression. In addition to VISAR capability, methods for measuring shock velocity have also been developed for shock studies on Z. When used in conjunction with the Rankine- Hugoniot jump conditions, material response at high temperatures and pressures can be inferred. Radiation in the Z accelerator is produced when approximately 18 MA are passed through a cylindrical wire array typically 20 to 50 mm in diameter and 10 to 20 mm in height. 200-300more » wires with initial diameters on the order of 8 to 20 micron form, upon application of the current, a plasma shell, which is magnetically imploded until it collapses and stagnates on axis, forming a dense plasma emitter in the shape of a column, referred to as a" z pinch". The initial wire array and subsequent plasma pinch are confined within a metallic can, referred to as a primary hohlraum, which serves as both a current return path and a reflective surface to contain the radiation. Attached to openings in the primary hohlraum wall are smaller tubes referred to as secondaries. Multiple secondaries can be fielded on most experiments, which are the typical location for mounting EOS samples. In this configuration, the secondary S1 contains two separate VISAR probes for making velocity measurements at different material thicknesses. By correlating the resulting velocity profiles in time, a measurement of shock velocity can be determined. In addition, the velocity profiles provide the Hugoniot particle velocity after the records were impedance-matched. Secondaries S2 and S3 provide measurements of shock velocity using laser light reflected from steps. As the shock arrives at each of these surfaces, the surface reflectivity significantly decreases, which causes a sharp drop in return light. The shock velocity can be inferred from shock arrival at different steps The z-pinch technique is particularly useful for producing high amplitude shock waves for EOS applications. An alternative approach for using Z is to produce shockless loading directly with the magnetic pressure in the accelerator.« less

Authors:
; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Sandia National Laboratories, Albuquerque, NM, and Livermore, CA
Sponsoring Org.:
USDOE
OSTI Identifier:
1907
Report Number(s):
SAND98-2535C
ON: DE00001907
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Conference
Resource Relation:
Conference: 22nd International Symposium on Shock Waves; London, UK; 07/18-23/1999
Country of Publication:
United States
Language:
English
Subject:
66 PHYSICS; 45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE; Shock Waves; Equations of State; Weapons

Citation Formats

Asay, J.R., Bernard, M.A., Clark, B., Fleming, K.J., Hall, C.A., Hauer, A., McDaniel, D.H., Slutz, S.A., Spielman, R.B., Stygar, W.A., and Trott, W.M. Use of Z-Pinch Techniques for Equation of State Applications. United States: N. p., 1998. Web.
Asay, J.R., Bernard, M.A., Clark, B., Fleming, K.J., Hall, C.A., Hauer, A., McDaniel, D.H., Slutz, S.A., Spielman, R.B., Stygar, W.A., & Trott, W.M. Use of Z-Pinch Techniques for Equation of State Applications. United States.
Asay, J.R., Bernard, M.A., Clark, B., Fleming, K.J., Hall, C.A., Hauer, A., McDaniel, D.H., Slutz, S.A., Spielman, R.B., Stygar, W.A., and Trott, W.M. Wed . "Use of Z-Pinch Techniques for Equation of State Applications". United States. https://www.osti.gov/servlets/purl/1907.
@article{osti_1907,
title = {Use of Z-Pinch Techniques for Equation of State Applications},
author = {Asay, J.R. and Bernard, M.A. and Clark, B. and Fleming, K.J. and Hall, C.A. and Hauer, A. and McDaniel, D.H. and Slutz, S.A. and Spielman, R.B. and Stygar, W.A. and Trott, W.M.},
abstractNote = {A principal goal of the shock physics program at Sandia is to establish a capability to make accurate equation of state (EOS) measurements on the Z pulsed radiation source. The Z accelerator is a source of intense x-ray radiation, which can be used to drive ablative shocks for EOS studies. With this source, ablative multi shocks can be produced to study materials over the range of interest to both weapons and ICF physics programs. In developing the capability to diagnose these types of studies on Z, techniques commonly used in conventional impact generated experimental were implemented. The primary diagnostic presently being used for this work is velocity interferometry, VISAR, which not only provides Hugoniot particle velocity measurements, but also measurements of non-shock EOS measurements, such as isentropic compression. In addition to VISAR capability, methods for measuring shock velocity have also been developed for shock studies on Z. When used in conjunction with the Rankine- Hugoniot jump conditions, material response at high temperatures and pressures can be inferred. Radiation in the Z accelerator is produced when approximately 18 MA are passed through a cylindrical wire array typically 20 to 50 mm in diameter and 10 to 20 mm in height. 200-300 wires with initial diameters on the order of 8 to 20 micron form, upon application of the current, a plasma shell, which is magnetically imploded until it collapses and stagnates on axis, forming a dense plasma emitter in the shape of a column, referred to as a" z pinch". The initial wire array and subsequent plasma pinch are confined within a metallic can, referred to as a primary hohlraum, which serves as both a current return path and a reflective surface to contain the radiation. Attached to openings in the primary hohlraum wall are smaller tubes referred to as secondaries. Multiple secondaries can be fielded on most experiments, which are the typical location for mounting EOS samples. In this configuration, the secondary S1 contains two separate VISAR probes for making velocity measurements at different material thicknesses. By correlating the resulting velocity profiles in time, a measurement of shock velocity can be determined. In addition, the velocity profiles provide the Hugoniot particle velocity after the records were impedance-matched. Secondaries S2 and S3 provide measurements of shock velocity using laser light reflected from steps. As the shock arrives at each of these surfaces, the surface reflectivity significantly decreases, which causes a sharp drop in return light. The shock velocity can be inferred from shock arrival at different steps The z-pinch technique is particularly useful for producing high amplitude shock waves for EOS applications. An alternative approach for using Z is to produce shockless loading directly with the magnetic pressure in the accelerator.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1998},
month = {11}
}

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