Modeling Variable-Impedance, Magnetically Insulated, Transmission Lines

Journal Article · Sat Jun 01 00:00:00 EDT 2019 · IEEE Pulsed Power Conference (Online)

DOI:https://doi.org/10.1109/ppps34859.2019.9009993· OSTI ID:1724571

Spielman, R. B. ^[1]; Sefkow, A. B. ^[2]

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1. Univ. of Rochester, NY (United States). Lab. for Laser Energetics; Laboratory for Laser Energetics, University of Rochester
2. Univ. of Rochester, NY (United States). Lab. for Laser Energetics

Coupling generator current to electron-beam loads and dynamic-inductance loads (z pinches) is greatly improved with low-inductance vacuum transmission lines. Typically, magnetically insulated transmission lines (MITLs) utilize nearly constant impedance geometries where the minimum impedance (anode-cathode gap) is limited by electron loss during the setup of magnetic insulation. Constant-impedance MITL designs are not optimized for low inductance (Zτ) when given a constraint on vacuum electron flow. We describe the design and the modeling of MITLs that have a nonconstant impedance. The baseline variable-impedance MITL designs are based on equilibrium vacuum-electron flow models [1] that are incorporated into the Screamer circuit code [2]. Such designs satisfy the MITL limits in the areal density of the loss current and have magnetically insulated flow that is stable everywhere along the MITL. Different MITL designs are then modeled analytically and with a 2-D particle-in-cell computer code in order to quantify subtle electron losses driven by changes to the vacuum impedance as a function of distance along the transmission line. We present a variable-impedance MITL design that delivers more current with a lower inductance than found in constant-impedance MITL designs.

• Research Organization: Univ. of Rochester, NY (United States). Lab. for Laser Energetics
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Fusion Energy Sciences (FES)
• Grant/Contract Number: NA0001944; NA0003856; SC0017951
• OSTI ID: 1724571
• Report Number(s): 2019--256,1598,2553; 2019-256, 1598, 2553
• Journal Information: IEEE Pulsed Power Conference (Online), Journal Name: IEEE Pulsed Power Conference (Online) Vol. 2019; ISSN 2158-4923
• Publisher: IEEE
• Country of Publication: United States
• Language: English

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