Plasma evolution and dynamics in high-power vacuum-transmission-line post-hole convolutes

Vacuum-post-hole convolutes are used in pulsed high-power generators to join several magnetically insulated transmission lines (MITL) in parallel. Such convolutes add the output currents of the MITLs, and deliver the combined current to a single MITL that, in turn, delivers the current to a load. Ma...

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Main Authors: D. V. Rose, D. R. Welch, T. P. Hughes, R. E. Clark, W. A. Stygar
Format: Article
Language:English
Published: American Physical Society 2008-06-01
Series:Physical Review Special Topics. Accelerators and Beams
Online Access:http://doi.org/10.1103/PhysRevSTAB.11.060401
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author D. V. Rose
D. R. Welch
T. P. Hughes
R. E. Clark
W. A. Stygar
author_facet D. V. Rose
D. R. Welch
T. P. Hughes
R. E. Clark
W. A. Stygar
author_sort D. V. Rose
collection DOAJ
description Vacuum-post-hole convolutes are used in pulsed high-power generators to join several magnetically insulated transmission lines (MITL) in parallel. Such convolutes add the output currents of the MITLs, and deliver the combined current to a single MITL that, in turn, delivers the current to a load. Magnetic insulation of electron flow, established upstream of the convolute region, is lost at the convolute due to symmetry breaking and the formation of magnetic nulls, resulting in some current losses. At very high-power operating levels and long pulse durations, the expansion of electrode plasmas into the MITL of such devices is considered likely. This work examines the evolution and dynamics of cathode plasmas in the double-post-hole convolutes used on the Z accelerator [R. B. Spielman et al., Phys. Plasmas 5, 2105 (1998)PHPAEN1070-664X10.1063/1.872881]. Three-dimensional particle-in-cell (PIC) simulations that model the entire radial extent of the Z accelerator convolute—from the parallel-plate transmission-line power feeds to the z-pinch load region—are used to determine electron losses in the convolute. The results of the simulations demonstrate that significant current losses (1.5 MA out of a total system current of 18.5 MA), which are comparable to the losses observed experimentally, could be caused by the expansion of cathode plasmas in the convolute regions.
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spelling doaj.art-b465bbf2d741437e8d7840cbf803c5ab2022-12-21T17:56:59ZengAmerican Physical SocietyPhysical Review Special Topics. Accelerators and Beams1098-44022008-06-0111606040110.1103/PhysRevSTAB.11.060401Plasma evolution and dynamics in high-power vacuum-transmission-line post-hole convolutesD. V. RoseD. R. WelchT. P. HughesR. E. ClarkW. A. StygarVacuum-post-hole convolutes are used in pulsed high-power generators to join several magnetically insulated transmission lines (MITL) in parallel. Such convolutes add the output currents of the MITLs, and deliver the combined current to a single MITL that, in turn, delivers the current to a load. Magnetic insulation of electron flow, established upstream of the convolute region, is lost at the convolute due to symmetry breaking and the formation of magnetic nulls, resulting in some current losses. At very high-power operating levels and long pulse durations, the expansion of electrode plasmas into the MITL of such devices is considered likely. This work examines the evolution and dynamics of cathode plasmas in the double-post-hole convolutes used on the Z accelerator [R. B. Spielman et al., Phys. Plasmas 5, 2105 (1998)PHPAEN1070-664X10.1063/1.872881]. Three-dimensional particle-in-cell (PIC) simulations that model the entire radial extent of the Z accelerator convolute—from the parallel-plate transmission-line power feeds to the z-pinch load region—are used to determine electron losses in the convolute. The results of the simulations demonstrate that significant current losses (1.5 MA out of a total system current of 18.5 MA), which are comparable to the losses observed experimentally, could be caused by the expansion of cathode plasmas in the convolute regions.http://doi.org/10.1103/PhysRevSTAB.11.060401
spellingShingle D. V. Rose
D. R. Welch
T. P. Hughes
R. E. Clark
W. A. Stygar
Plasma evolution and dynamics in high-power vacuum-transmission-line post-hole convolutes
Physical Review Special Topics. Accelerators and Beams
title Plasma evolution and dynamics in high-power vacuum-transmission-line post-hole convolutes
title_full Plasma evolution and dynamics in high-power vacuum-transmission-line post-hole convolutes
title_fullStr Plasma evolution and dynamics in high-power vacuum-transmission-line post-hole convolutes
title_full_unstemmed Plasma evolution and dynamics in high-power vacuum-transmission-line post-hole convolutes
title_short Plasma evolution and dynamics in high-power vacuum-transmission-line post-hole convolutes
title_sort plasma evolution and dynamics in high power vacuum transmission line post hole convolutes
url http://doi.org/10.1103/PhysRevSTAB.11.060401
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