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Title: Mitigation of Magneto Rayleigh Taylor Instability

Abstract

Reported herein is a comprehensive study of magneto-Rayleigh-Taylor instability conducted at the University of Michigan, using a one mega-ampere linear transformer driver on a cylindrical thin foil. It is a combined theoretical and experimental effort, on both magnetized and nonmagnetized liners, unseeded and seeded with a helical perturbation, and for a thin foil that is stationary, imploding or exploding. Also studied is the electrothermal instability, thought to be the seed for magneto-Rayleigh-Taylor instability. These subjects are important to magnetized liner inertial fusion (MagLIF). We interpret the helical features usually observed in a magnetized cylindrical liner as a manifestation of a discrete eigenmode, from implosion to stagnation. We discover that the observed pitch angle (phi) of the helix follows the simple relation, phi = m/kR, for both MagLIF experiments at the Sandia National Laboratories, and for our experiments, where m is the azimuthal mode number, k is the axial mode number, and R is the radius of the helical feature. This discrete mode persists from implosion to explosion, even through the highly nonlinear stage where the axial perturbations clump together. When the latter occurs, we propose a simultaneous decrease of mode numbers, from (m, k) to (m/2, k/2), kinematically. We show,more » both theoretically and experimentally, that higher m modes are excited with higher axial magnetic field. We find that seeding is far more important than the intrinsic instability of a magnetized liner. On the electro-thermal instability, we discover that refractory metals with a low ratio of critical temperature to melting temperature (i.e. tantalum) are very robust against electrothermal instability. We perform the first experiments that show the transition of electrothermal instability from the striation to filamentation mode. We experimentally confirm the importance of surface defects in the development of the electrothermal instability. We develop and publish a fabrication method for ultra-thin metallic liners. Three (3) graduate students completed their PhD theses with the support of this grant.« less

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [2]
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  1. Univ. of Michigan, Ann Arbor, MI (United States)
  2. University of Univ. of Michigan, Ann Arbor, MI (United States)
Publication Date:
Research Org.:
Univ. of Michigan, Ann Arbor, MI (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
OSTI Identifier:
1436495
Report Number(s):
DOE-UM-12328-1
DOE Contract Number:  
SC0012328
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; magneto Rayleigh-Taylor; electrothermal instability; magnetohydrodynamic instabilities; sausage mode; kink mode; MagLIF; liner stability; cylindrical implosions

Citation Formats

Lau, Y. Y., Gilgenbach, Ronald M., and Jordan, Nicholas M. Mitigation of Magneto Rayleigh Taylor Instability. United States: N. p., 2018. Web. doi:10.2172/1436495.
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Lau, Y. Y., Gilgenbach, Ronald M., & Jordan, Nicholas M. Mitigation of Magneto Rayleigh Taylor Instability. United States. doi:10.2172/1436495.
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Lau, Y. Y., Gilgenbach, Ronald M., and Jordan, Nicholas M. Mon . "Mitigation of Magneto Rayleigh Taylor Instability". United States. doi:10.2172/1436495. https://www.osti.gov/servlets/purl/1436495.
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@article{osti_1436495,
title = {Mitigation of Magneto Rayleigh Taylor Instability},
author = {Lau, Y. Y. and Gilgenbach, Ronald M. and Jordan, Nicholas M.},
abstractNote = {Reported herein is a comprehensive study of magneto-Rayleigh-Taylor instability conducted at the University of Michigan, using a one mega-ampere linear transformer driver on a cylindrical thin foil. It is a combined theoretical and experimental effort, on both magnetized and nonmagnetized liners, unseeded and seeded with a helical perturbation, and for a thin foil that is stationary, imploding or exploding. Also studied is the electrothermal instability, thought to be the seed for magneto-Rayleigh-Taylor instability. These subjects are important to magnetized liner inertial fusion (MagLIF). We interpret the helical features usually observed in a magnetized cylindrical liner as a manifestation of a discrete eigenmode, from implosion to stagnation. We discover that the observed pitch angle (phi) of the helix follows the simple relation, phi = m/kR, for both MagLIF experiments at the Sandia National Laboratories, and for our experiments, where m is the azimuthal mode number, k is the axial mode number, and R is the radius of the helical feature. This discrete mode persists from implosion to explosion, even through the highly nonlinear stage where the axial perturbations clump together. When the latter occurs, we propose a simultaneous decrease of mode numbers, from (m, k) to (m/2, k/2), kinematically. We show, both theoretically and experimentally, that higher m modes are excited with higher axial magnetic field. We find that seeding is far more important than the intrinsic instability of a magnetized liner. On the electro-thermal instability, we discover that refractory metals with a low ratio of critical temperature to melting temperature (i.e. tantalum) are very robust against electrothermal instability. We perform the first experiments that show the transition of electrothermal instability from the striation to filamentation mode. We experimentally confirm the importance of surface defects in the development of the electrothermal instability. We develop and publish a fabrication method for ultra-thin metallic liners. Three (3) graduate students completed their PhD theses with the support of this grant.},
doi = {10.2172/1436495},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2018},
month = {5}
}
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Technical Report:
View Technical Report (2.53 MB)
DOI:  10.2172/1436495
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Works referenced in this record:

Seeded and unseeded helical modes in magnetized, non-imploding cylindrical liner-plasmas
journal, October 2016

  • Yager-Elorriaga, D. A.; Zhang, P.; Steiner, A. M.
  • Physics of Plasmas, Vol. 23, Issue 10
  • DOI: 10.1063/1.4965240

Determination of plasma pinch time and effective current radius of double planar wire array implosions from current measurements on a 1-MA linear transformer driver
journal, October 2016

  • Steiner, Adam M.; Yager-Elorriaga, David A.; Patel, Sonal G.
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  • DOI: 10.1063/1.4965241

Discrete helical modes in imploding and exploding cylindrical, magnetized liners
journal, December 2016

  • Yager-Elorriaga, D. A.; Zhang, P.; Steiner, A. M.
  • Physics of Plasmas, Vol. 23, Issue 12
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Coupling of sausage, kink, and magneto-Rayleigh-Taylor instabilities in a cylindrical liner
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Double and Single Planar Wire Arrays on University-Scale Low-Impedance LTD Generator
journal, April 2016

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Evolution of sausage and helical modes in magnetized thin-foil cylindrical liners driven by a Z-pinch
journal, May 2018

  • Yager-Elorriaga, D. A.; Lau, Y. Y.; Zhang, P.
  • Physics of Plasmas, Vol. 25, Issue 5
  • DOI: 10.1063/1.5017849

Technique for fabrication of ultrathin foils in cylindrical geometry for liner-plasma implosion experiments with sub-megaampere currents
journal, November 2015

  • Yager-Elorriaga, D. A.; Steiner, A. M.; Patel, S. G.
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The electro-thermal stability of tantalum relative to aluminum and titanium in cylindrical liner ablation experiments at 550 kA
journal, March 2018

  • Steiner, Adam M.; Campbell, Paul C.; Yager-Elorriaga, David A.
  • Physics of Plasmas, Vol. 25, Issue 3
  • DOI: 10.1063/1.5012891

Temporal evolution of surface ripples on a finite plasma slab subject to the magneto-Rayleigh-Taylor instability
journal, December 2014

  • Weis, M. R.; Zhang, P.; Lau, Y. Y.
  • Physics of Plasmas, Vol. 21, Issue 12
  • DOI: 10.1063/1.4904210
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