Pulse width dependence of magnetic field generation using laser-powered capacitor coils

Abraham Chien, Lan Gao, Shu Zhang, Hantao Ji, Eric Blackman, Hui Chen, Gennady Fiksel, Kenneth Hill, Philip Nilson

Research output: Contribution to journalArticlepeer-review

Abstract

Megagauss magnetic fields were generated by a current flowing through a U-shaped coil connecting two parallel copper foils. Two kJ-class lasers at various pulse widths from 2 ns to 9.9 ns passed through holes in the front foil and were focused on the back foil with an intensity of ∼1.7×1016 W/cm2. The coil current and resulting magnetic fields were characterized using ultrafast proton radiography, timed at the end of the laser pulses. The measurements show that magnetic field strength decays with increasing laser pulse width. A lumped-circuit model was developed and showed consistency with the experimental measurements, demonstrating an ion shorting effect: as the ion current neutralizes the electron current contribution to interplate voltage, the coil current peaks on a timescale close to the ion transit time ti=d/vion. FLASH simulations of the coil current are performed, and the calculated resistance values are used to constrain ion speed as a function of hot electron temperature.

Original languageEnglish (US)
Article number052105
JournalPhysics of Plasmas
Volume28
Issue number5
DOIs
StatePublished - May 1 2021

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics

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