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Title: Losses at magnetic nulls in pulsed-power transmission line systems

Abstract

Pulsed-power systems operating in the terawatt regime must deal with large electron flows in vacuum transmission lines. In most parts of these transmission lines the electrons are constrained by the self-magnetic field to flow parallel to the conductors. In very low impedance systems, such as those used to drive Z-pinch radiation sources, the currents from multiple transmission lines are added together. This addition necessarily involves magnetic nulls that connect the positive and negative electrodes. The resultant local loss of magnetic insulation results in electron losses at the anode in the vicinity of the nulls. The lost current due to the magnetic null might or might not be appreciable. In some cases the lost current due to the null is not large, but is spatially localized, and may create a gas and plasma release from the anode that can lead to an excessive loss, and possibly to catastrophic damage to the hardware. In this paper we describe an analytic model that uses one geometric parameter (aside from straightforward hardware size measurements) that determines the loss to the anode, and the extent of the loss region when the driving source and load are known. The parameter can be calculated in terms ofmore » the magnetic field in the region of the null calculated when no electron flow is present. The model is compared to some experimental data, and to simulations of several different hardware geometries, including some cases with multiple nulls, and unbalanced feeds.« less

Authors:
; ; ; ; ;  [1];  [2]
  1. Sandia National Laboratories, Albuquerque, New Mexico 87185-1152 (United States)
  2. (France)
Publication Date:
OSTI Identifier:
20782760
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 13; Journal Issue: 4; Other Information: DOI: 10.1063/1.2192731; (c) 2006 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; ANODES; COMPUTERIZED SIMULATION; ELECTRIC CONDUCTORS; ELECTRIC CURRENTS; ELECTRONS; GEOMETRY; IMPEDANCE; LINEAR Z PINCH DEVICES; LONGITUDINAL PINCH; MAGNETIC FIELDS; MAGNETIC INSULATION; PLASMA; PLASMA SIMULATION; POWER TRANSMISSION LINES; RADIATION SOURCES

Citation Formats

Mendel, C.W. Jr., Pointon, T.D., Savage, M.E., Seidel, D.B., Magne, I., Vezinet, R., and Centre d'Etudes de Gramat, Gramat. Losses at magnetic nulls in pulsed-power transmission line systems. United States: N. p., 2006. Web. doi:10.1063/1.2192731.
Mendel, C.W. Jr., Pointon, T.D., Savage, M.E., Seidel, D.B., Magne, I., Vezinet, R., & Centre d'Etudes de Gramat, Gramat. Losses at magnetic nulls in pulsed-power transmission line systems. United States. doi:10.1063/1.2192731.
Mendel, C.W. Jr., Pointon, T.D., Savage, M.E., Seidel, D.B., Magne, I., Vezinet, R., and Centre d'Etudes de Gramat, Gramat. Sat . "Losses at magnetic nulls in pulsed-power transmission line systems". United States. doi:10.1063/1.2192731.
@article{osti_20782760,
title = {Losses at magnetic nulls in pulsed-power transmission line systems},
author = {Mendel, C.W. Jr. and Pointon, T.D. and Savage, M.E. and Seidel, D.B. and Magne, I. and Vezinet, R. and Centre d'Etudes de Gramat, Gramat},
abstractNote = {Pulsed-power systems operating in the terawatt regime must deal with large electron flows in vacuum transmission lines. In most parts of these transmission lines the electrons are constrained by the self-magnetic field to flow parallel to the conductors. In very low impedance systems, such as those used to drive Z-pinch radiation sources, the currents from multiple transmission lines are added together. This addition necessarily involves magnetic nulls that connect the positive and negative electrodes. The resultant local loss of magnetic insulation results in electron losses at the anode in the vicinity of the nulls. The lost current due to the magnetic null might or might not be appreciable. In some cases the lost current due to the null is not large, but is spatially localized, and may create a gas and plasma release from the anode that can lead to an excessive loss, and possibly to catastrophic damage to the hardware. In this paper we describe an analytic model that uses one geometric parameter (aside from straightforward hardware size measurements) that determines the loss to the anode, and the extent of the loss region when the driving source and load are known. The parameter can be calculated in terms of the magnetic field in the region of the null calculated when no electron flow is present. The model is compared to some experimental data, and to simulations of several different hardware geometries, including some cases with multiple nulls, and unbalanced feeds.},
doi = {10.1063/1.2192731},
journal = {Physics of Plasmas},
number = 4,
volume = 13,
place = {United States},
year = {Sat Apr 15 00:00:00 EDT 2006},
month = {Sat Apr 15 00:00:00 EDT 2006}
}
  • Pulsed-power systems operating in the terawatt regime must deal with large electron flows in vacuum transmission lines. In most parts of these transmission lines the electrons are constrained by the self-magnetic field to flow parallel to the conductors. In very low impedance systems, such as those used to drive Z-pinch radiation sources, the currents from multiple transmission lines are added together. This addition necessarily involves magnetic nulls that connect the positive and negative electrodes. The resultant local loss of magnetic insulation results in electron losses at the anode in the vicinity of the nulls. The lost current due to themore » magnetic null might or might not be appreciable. In some cases the lost current due to the null is not large, but is spatially localized, and may create a gas and plasma release from the anode that can lead to an excessive loss, and possibly to catastrophic damage to the hardware. In this paper we describe an analytic model that uses one geometric parameter (aside from straightforward hardware size measurements) that determines the loss to the anode, and the extent of the loss region when the driving source and load are known. The parameter can be calculated in terms of the magnetic field in the region of the null calculated when no electron flow is present. The model is compared to some experimental data, and to simulations of several different hardware geometries, including some cases with multiple nulls, and unbalanced feeds.« less
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