skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Thermodynamical calculation of metal heating in nanosecond exploding wire and foil experiments

Abstract

A method of thermodynamical calculation of thin metal wire heating during its electrical explosion is discussed. The technique is based on a calculation of Joule energy deposition taking into account the current wave form and the temperature dependence of the resistivity and heat capacity of the metal. Comparing the calculation to a set of exploding tungsten wire experiments demonstrates good agreement up to the time of melting. Good agreement is also demonstrated with resistive magnetohydrodynamics simulation. A similar thermodynamical calculation for Mo, Ti, Ni, Fe, Al, and Cu shows good agreement with experimental data. The thermodynamical technique is useful for verification of the voltage measurements in exploding wire experiments. This technique also shows good agreement with an exploding W foil experiment.

Authors:
; ;  [1];  [2]
  1. Ktech Corporation, 10800 Gibson Boulevard, Albuquerque, New Mexico 87123 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20953418
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 78; Journal Issue: 4; Other Information: DOI: 10.1063/1.2712938; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ALUMINIUM; COPPER; EXPLODING WIRES; FOILS; HEATING; IRON; MAGNETOHYDRODYNAMICS; MELTING; MELTING POINTS; MOLYBDENUM; NICKEL; PLASMA; PLASMA SIMULATION; SPECIFIC HEAT; TEMPERATURE DEPENDENCE; TITANIUM; TUNGSTEN

Citation Formats

Sarkisov, G. S., Rosenthal, S. E., Struve, K. W., and Sandia National Laboratories, Albuquerque, New Mexico 87110. Thermodynamical calculation of metal heating in nanosecond exploding wire and foil experiments. United States: N. p., 2007. Web. doi:10.1063/1.2712938.
Sarkisov, G. S., Rosenthal, S. E., Struve, K. W., & Sandia National Laboratories, Albuquerque, New Mexico 87110. Thermodynamical calculation of metal heating in nanosecond exploding wire and foil experiments. United States. doi:10.1063/1.2712938.
Sarkisov, G. S., Rosenthal, S. E., Struve, K. W., and Sandia National Laboratories, Albuquerque, New Mexico 87110. Sun . "Thermodynamical calculation of metal heating in nanosecond exploding wire and foil experiments". United States. doi:10.1063/1.2712938.
@article{osti_20953418,
title = {Thermodynamical calculation of metal heating in nanosecond exploding wire and foil experiments},
author = {Sarkisov, G. S. and Rosenthal, S. E. and Struve, K. W. and Sandia National Laboratories, Albuquerque, New Mexico 87110},
abstractNote = {A method of thermodynamical calculation of thin metal wire heating during its electrical explosion is discussed. The technique is based on a calculation of Joule energy deposition taking into account the current wave form and the temperature dependence of the resistivity and heat capacity of the metal. Comparing the calculation to a set of exploding tungsten wire experiments demonstrates good agreement up to the time of melting. Good agreement is also demonstrated with resistive magnetohydrodynamics simulation. A similar thermodynamical calculation for Mo, Ti, Ni, Fe, Al, and Cu shows good agreement with experimental data. The thermodynamical technique is useful for verification of the voltage measurements in exploding wire experiments. This technique also shows good agreement with an exploding W foil experiment.},
doi = {10.1063/1.2712938},
journal = {Review of Scientific Instruments},
number = 4,
volume = 78,
place = {United States},
year = {Sun Apr 15 00:00:00 EDT 2007},
month = {Sun Apr 15 00:00:00 EDT 2007}
}
  • A basic problem in exploding-foil experiments is the placement of the voltage probes since they cannot be located at the ideal position where the voltage drop shoud be measured. As a result, they are placed so that they introduce error into the measurements. Therefore, knowing how much experimental error exists in these voltage measurements is quite important. In this study, a theoretical determination of the potential drop in a nonlinear conductor is made using both steady-state and dynamic models. Estimates of the magnitude of experimental errors are calculated.
  • Two low energy (1.6 and 8 kJ) portable electrically exploding foil accelerators are developed for moderately high pressure shock studies at small laboratory scale. Projectile velocities up to 4.0 km/s have been measured on Kapton flyers of thickness 125 {mu}m and diameter 8 mm, using an in-house developed Fabry-Perot velocimeter. An asymmetric tilt of typically few milliradians has been measured in flyers using fiber optic technique. High pressure impact experiments have been carried out on tantalum, and aluminum targets up to pressures of 27 and 18 GPa, respectively. Peak particle velocities at the target-glass interface as measured by Fabry-Perot velocimetermore » have been found in good agreement with the reported equation of state data. A one-dimensional hydrodynamic code based on realistic models of equation of state and electrical resistivity has been developed to numerically simulate the flyer velocity profiles. The developed numerical scheme is validated against experimental and simulation data reported in literature on such systems. Numerically computed flyer velocity profiles and final flyer velocities have been found in close agreement with the previously reported experimental results with a significant improvement over reported magnetohydrodynamic simulations. Numerical modeling of low energy systems reported here predicts flyer velocity profiles higher than experimental values, indicating possibility of further improvement to achieve higher shock pressures.« less
  • Wire-array Z-pinch implosion experiments begin with wire heating, explosion, and plasma formation phases that are driven by an initial 50--100 ns, 0--1 kA/wire portion of the current pulse. This paper presents expansion rates for the dense, exploding wire cores for several wire materials under these conditions, with and without insulating coatings, and shows that these rates are related to the energy deposition prior to plasma formation around the wire. The most rapid and uniform expansion occurs for wires in which the initial energy deposition is a substantial fraction of the energy required to completely vaporize the wire. Conversely, wire materialsmore » with less energy deposition relative to the vaporization energy show complex internal structure and the slowest, most nonuniform expansion. This paper also presents calibrated radial density profiles for some Ag wire explosions, and structural details present in some wire explosions, such as foam-like appearance, stratified layers and gaps.« less
  • We investigate the validity of the surface electric-field interaction model in beam-foil experiments where the polarization of the emitted light is measured. After summarizing the theory for expanding the density operator into state multipoles and linking these to the Stokes parameters of the light, we show also how to use symmetries to reduce the size of the calculations. A very simple model is chosen for the electric field: it is perpendicular to the foil and constant over a finite distance, then zero. This model is used to find the initial density matrix for the {ital n}=3 singlet states of Hemore » I and the electric-field parameters from tilted-foil experiments. Reasonable results are obtained given the unrealistic electric-field model used.« less
  • X-ray backlighter images (radiographs) of current-induced explosions of 12.7-25 {mu}m diam Al wires have been used to determine the expansion rate and internal structure of the dense wire cores. The current rises to 1-4.5 kA per wire in 350 ns, but voltage and current measurements show that the energy driving the explosion is deposited resistively during the first 40-50 ns, when the current is only a few hundred amperes per wire. A voltage collapse then occurs as a result of plasma formation around the wire, effectively terminating the energy deposition in the wire core. High-resolution radiographs obtained over the nextmore » 150-200 ns show the expanding wire cores to have significant axial stratification and foamlike structures with {approx}10 {mu}m scale lengths over most of the wire length before they disappear in the expansion process. The expansion rate of the portion of the wire cores that is dense enough to be detected by radiography is 1.4-2 {mu}m/ns commencing approximately 25 ns after the moment of the voltage collapse. (The sensitivity limit is equivalent to 0.2 {mu}m of solid density Al.) By 250 ns after the start of the current pulse, the detectable wire core diameter is 250 {mu}m, but it contains only about 30% of the initial wire material. (c) 2000 American Institute of Physics.« less