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Title: Effect of driver impedance on dense plasma focus Z-pinch neutron yield

The Z-pinch phase of a dense plasma focus (DPF) heats the plasma by rapid compression and accelerates ions across its intense electric fields, producing neutrons through both thermonuclear and beam-target fusion. Driver characteristics have empirically been shown to affect performance, as measured by neutron yield per unit of stored energy. We are exploring the effect of driver characteristics on DPF performance using particle-in-cell (PIC) simulations of a kJ scale DPF. In this work, our PIC simulations are fluid for the run-down phase and transition to fully kinetic for the pinch phase, capturing kinetic instabilities, anomalous resistivity, and beam formation during the pinch. The anode-cathode boundary is driven by a circuit model of the capacitive driver, including system inductance, the load of the railgap switches, the guard resistors, and the coaxial transmission line parameters. It is known that the driver impedance plays an important role in the neutron yield: first, it sets the peak current achieved at pinch time; and second, it affects how much current continues to flow through the pinch when the pinch inductance and resistance suddenly increase. Here we show from fully kinetic simulations how total neutron yield depends on the impedance of the driver and the distributedmore » parameters of the transmission circuit. Direct comparisons between the experiment and simulations enhance our understanding of these plasmas and provide predictive design capability for neutron source applications.« less
Authors:
; ;  [1] ;  [2]
  1. Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States)
  2. Voss Scientific, Albuquerque, NM 87108 (United States)
Publication Date:
OSTI Identifier:
22390820
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1639; Journal Issue: 1; Conference: 9. International Conference on Dense Z Pinches, Napa, CA (United States), 3-7 Aug 2014; Other Information: (c) 2014 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; ANODES; CATHODES; COMPARATIVE EVALUATIONS; ELECTRIC FIELDS; IMPEDANCE; INDUCTANCE; LINEAR Z PINCH DEVICES; NEUTRON SOURCES; NEUTRONS; PLASMA DENSITY; PLASMA FOCUS; PLASMA SIMULATION; POWER TRANSMISSION LINES; RESISTORS; STORED ENERGY; YIELDS