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Title: Megagauss-level magnetic field production in cm-scale auto-magnetizing helical liners pulsed to 500 kA in 125 ns

Abstract

We present Auto-magnetizing (AutoMag) liners [Slutz et al., Phys. Plasmas 24, 012704 (2017)] are designed to generate up to 100 T of axial magnetic field in the fuel for Magnetized Liner Inertial Fusion [Slutz et al., Phys. Plasmas 17, 056303 (2010)] without the need for external field coils. AutoMag liners (cylindrical tubes) are composed of discrete metallic helical conduction paths separated by electrically insulating material. Initially, helical current in the AutoMag liner produces internal axial magnetic field during a long (100 to 300 ns) current prepulse with an average current rise rate dI/dt=5 kA/ns. After the cold fuel is magnetized, a rapidly rising current (200 kA/ns) generates a calculated electric field of 64 MV/m between the helices. Such field is sufficient to force dielectric breakdown of the insulating material after which liner current is reoriented from helical to predominantly axial which ceases the AutoMag axial magnetic field production mechanism and the z-pinch liner implodes. Proof of concept experiments have been executed on the Mykonos linear transformer driver to measure the axial field produced by a variety of AutoMag liners and to evaluate what physical processes drive dielectric breakdown. Lastly, a range of field strengths have been generated in various cm-scalemore » liners in agreement with magnetic transient simulations including a measured field above 90 T at I = 350 kA. By varying the helical pitch angle, insulator material, and insulator geometry, favorable liner designs have been identified for which breakdown occurs under predictable and reproducible field conditions.« less

Authors:
ORCiD logo [1];  [2]; ORCiD logo [2];  [2];  [2];  [3];  [4]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Univ. of New Mexico, Albuquerque, NM (United States). Electrical and Computer Engineering Department
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  3. Cornell Univ., Ithaca, NY (United States). Laboratory of Plasma Studies
  4. Univ. of Nevada, Reno, NV (United States). Department of Physics
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1441474
Alternate Identifier(s):
OSTI ID: 1435864
Report Number(s):
SAND-2018-1593J
Journal ID: ISSN 1070-664X; 663137
Grant/Contract Number:
AC04-94AL85000; NA0003525; 195306; 200269
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 25; Journal Issue: 5; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Shipley, Gabriel A., Awe, Thomas James, Hutsel, Brian Thomas, Slutz, Stephen A., Lamppa, Derek C., Greenly, John B., and Hutchinson, Trevor M. Megagauss-level magnetic field production in cm-scale auto-magnetizing helical liners pulsed to 500 kA in 125 ns. United States: N. p., 2018. Web. doi:10.1063/1.5028142.
Shipley, Gabriel A., Awe, Thomas James, Hutsel, Brian Thomas, Slutz, Stephen A., Lamppa, Derek C., Greenly, John B., & Hutchinson, Trevor M. Megagauss-level magnetic field production in cm-scale auto-magnetizing helical liners pulsed to 500 kA in 125 ns. United States. doi:10.1063/1.5028142.
Shipley, Gabriel A., Awe, Thomas James, Hutsel, Brian Thomas, Slutz, Stephen A., Lamppa, Derek C., Greenly, John B., and Hutchinson, Trevor M. Thu . "Megagauss-level magnetic field production in cm-scale auto-magnetizing helical liners pulsed to 500 kA in 125 ns". United States. doi:10.1063/1.5028142.
@article{osti_1441474,
title = {Megagauss-level magnetic field production in cm-scale auto-magnetizing helical liners pulsed to 500 kA in 125 ns},
author = {Shipley, Gabriel A. and Awe, Thomas James and Hutsel, Brian Thomas and Slutz, Stephen A. and Lamppa, Derek C. and Greenly, John B. and Hutchinson, Trevor M.},
abstractNote = {We present Auto-magnetizing (AutoMag) liners [Slutz et al., Phys. Plasmas 24, 012704 (2017)] are designed to generate up to 100 T of axial magnetic field in the fuel for Magnetized Liner Inertial Fusion [Slutz et al., Phys. Plasmas 17, 056303 (2010)] without the need for external field coils. AutoMag liners (cylindrical tubes) are composed of discrete metallic helical conduction paths separated by electrically insulating material. Initially, helical current in the AutoMag liner produces internal axial magnetic field during a long (100 to 300 ns) current prepulse with an average current rise rate dI/dt=5 kA/ns. After the cold fuel is magnetized, a rapidly rising current (200 kA/ns) generates a calculated electric field of 64 MV/m between the helices. Such field is sufficient to force dielectric breakdown of the insulating material after which liner current is reoriented from helical to predominantly axial which ceases the AutoMag axial magnetic field production mechanism and the z-pinch liner implodes. Proof of concept experiments have been executed on the Mykonos linear transformer driver to measure the axial field produced by a variety of AutoMag liners and to evaluate what physical processes drive dielectric breakdown. Lastly, a range of field strengths have been generated in various cm-scale liners in agreement with magnetic transient simulations including a measured field above 90 T at I = 350 kA. By varying the helical pitch angle, insulator material, and insulator geometry, favorable liner designs have been identified for which breakdown occurs under predictable and reproducible field conditions.},
doi = {10.1063/1.5028142},
journal = {Physics of Plasmas},
number = 5,
volume = 25,
place = {United States},
year = {Thu May 03 00:00:00 EDT 2018},
month = {Thu May 03 00:00:00 EDT 2018}
}

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