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Magnetic Reynolds Number and Neon Current Sheet Structure in the Axial Phase of a Plasma Focus

Abstract

The Magnetic Reynolds Number (MRN) in neon is computed as a function of Neon shock speed. The magnetic field profiles at various positions in the axial run down phase of the INTI Plasma Focus device are measured over a range of pressures from 2 to 20 Torr. These profiles are assessed for good electromagnetic coupling including measuring the current per unit current sheet thickness as a comparative measure of current sheet diffusion. It was found that at an axial current sheet speed of over 3.5 cm/μs (corresponding to MRN > 15), the current sheet has a compact profile with current density of 55 kA/cm of sheet thickness whereas at speeds below 2.8 cm/μs (corresponding to MRN < 10) the profile is more diffuse with current density less than 30 kA/cm of sheet thickness. Based on these studies it is proposed to take a speed of 3 cm/μs corresponding to an MRN of 10 as the minimum speed of neon current sheet below which the electromagnetic coupling begins to weaken.

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Correspondence to R. S. Rawat.

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Lee, S., Saw, S.H., Lee, P. et al. Magnetic Reynolds Number and Neon Current Sheet Structure in the Axial Phase of a Plasma Focus. J Fusion Energ 32, 50–55 (2013). https://doi.org/10.1007/s10894-012-9521-9

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Keywords

  • Magnetic Reynold Number
  • Shock speed
  • Plasma focus device
  • Current sheet diffusion