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On the Evolution From Micrometer-Scale Inhomogeneity to Global Overheated Structure During the Intense Joule Heating of a z-Pinch Rod

Journal Article · · IEEE Transactions on Plasma Science
 [1];  [1];  [2];  [1];  [3];  [3];  [3];  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  2. Univ. of New Mexico, Albuquerque, NM (United States)
  3. Univ. of Nevada, Reno, NV (United States)
+ Show Author Affiliations

Ultrafast optical microscopy of metal z-pinch rods pulsed with megaampere current is contributing new data and critical insight into what provides the fundamental seed for the magneto-Rayleigh-Taylor (MRT) instability. A two-frame near infrared/visible intensified-charge-coupled device gated imager with 2-ns temporal resolution and 3-μm spatial resolution captured emissions from the nonuniformly Joule heated surfaces of ultrasmooth aluminum (Al) rods. Nonuniform surface emissions are consistently first observed from discrete, 10-μm scale, subelectronvolt spots. Aluminum 6061 alloy, with micrometer-scale nonmetallic resistive inclusions, forms several times more spots than 99.999% pure Al 5N; 5-10 ns later, azimuthally stretched elliptical spots and distinct strata (40-100 μm wide by 10 μm tall) are observed on Al 6061, but not on Al 5N. In such overheat strata, aligned parallel to the magnetic field, we find that they are highly effective seeds for MRT instability growth. Our data give credence to the hypothesis that early nonuniform Joule heating, such as the electrothermal instability, may provide the dominant seed for MRT.

Research Organization:
Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
Sponsoring Organization:
USDOE National Nuclear Security Administration (NNSA)
Grant/Contract Number:
AC04-94AL85000
OSTI ID:
1357019
Report Number(s):
SAND2016--12472J; 649812
Journal Information:
IEEE Transactions on Plasma Science, Journal Name: IEEE Transactions on Plasma Science Journal Issue: 4 Vol. 45; ISSN 0093-3813
Publisher:
IEEECopyright Statement
Country of Publication:
United States
Language:
English

Cited By (7)

Metastable Fluid Decay During Electric Explosion of Metallic Foils journal December 2017
The electro-thermal stability of tantalum relative to aluminum and titanium in cylindrical liner ablation experiments at 550 kA journal March 2018
Investigation of surface evolution for stainless steel electrode under pulsed megagauss magnetic field journal February 2018
Significant change in threshold for plasma formation and evolution with small variation in copper alloys driven by a mega-ampere current pulse journal April 2019
The effect of the metal phase state on the growth of thermal instabilities in an electrically exploding conductor journal August 2019
Experimental observation of the stratified electrothermal instability on aluminum with thickness greater than a skin depth journal May 2018
Early Stage of the Explosion of Thin Flat Foils in a High-Current Diode at a Current of 40–80 kA journal June 2019

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Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
electrothermal effects
magnetic fields
optical imaging
plasma pinch
plasma stability