skip to main content

SciTech ConnectSciTech Connect

Title: Characterisation of the current switch mechanism in two-stage wire array Z-pinches

In this paper, we describe the operation of a two-stage wire array z-pinch driven by the 1.4 MA, 240 ns rise-time Magpie pulsed-power device at Imperial College London. In this setup, an inverse wire array acts as a fast current switch, delivering a current pre-pulse into a cylindrical load wire array, before rapidly switching the majority of the generator current into the load after a 100–150 ns dwell time. A detailed analysis of the evolution of the load array during the pre-pulse is presented. Measurements of the load resistivity and energy deposition suggest significant bulk heating of the array mass occurs. The ∼5 kA pre-pulse delivers ∼0.8 J of energy to the load, leaving it in a mixed, predominantly liquid-vapour state. The main current switch occurs as the inverse array begins to explode and plasma expands into the load region. Electrical and imaging diagnostics indicate that the main current switch may evolve in part as a plasma flow switch, driven by the expansion of a magnetic cavity and plasma bubble along the length of the load array. Analysis of implosion trajectories suggests that approximately 1 MA switches into the load in 100 ns, corresponding to a doubling of the generator dI/dt. Potential scaling of themore » device to higher current machines is discussed.« less
Authors:
; ; ; ; ; ; ; ; ; ; ;  [1] ;  [2]
  1. Blackett Laboratory, Imperial College, London SW7 2BW (United Kingdom)
  2. Sandia National Laboratories, Albuquerque, New Mexico 87185-1106 (United States)
Publication Date:
OSTI Identifier:
22489852
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 22; Journal Issue: 11; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; BUBBLES; CYLINDRICAL CONFIGURATION; ELECTRIC CURRENTS; ENERGY ABSORPTION; ENERGY LOSSES; HEATING; IMPLOSIONS; LIQUIDS; PLASMA; PULSE RISE TIME; PULSES; SWITCHES; TRAJECTORIES; VAPORS; WIRES