High repetition rate exploration of the Biermann battery effect in laser produced plasmas over large spatial regions

Abstract

In this paper we present a high-repetition-rate experimental platform for examining the spatial structure and evolution of Biermann generated magnetic fields in laser-produced plasmas. We have extended the work of prior experiments, which spanned over millimeter scales, by spatially measuring magnetic fields in multiple planes on centimeter scales over thousands of laser shots. Measurements with magnetic flux probes show azimuthally symmetric magnetic fields that range from 60 G at 0.7 cm from the target to 7 G at 4.2 cm from the target. The expansion rate of the magnetic fields and evolution of current density structures are also mapped and examined. Electron temperature and density of the laser-produced plasma are measured with optical Thomson scattering and used to directly calculate a magnetic Reynolds number of 1.4 × 10 4 , confirming that magnetic advection is dominant ≥ 1.5 cm from the target surface. The results are compared to FLASH simulations, which show qualitative agreement with the data.

The structure of 3-D collisional magnetized bow shocks in pulsed-power-driven plasma flows

“…2019; Pilgram et al. 2022) their perturbative nature leads to questions about how reliably they can reconstruct the magnetic field in plasma flows. These experiments additionally tackle this question by careful comparison between numerical simulations and experimental data.…”

“…Thus, the probe provides more information about the plasma than a passive obstacle. Although inductive probes are widely used in HEDP experiments, (Everson et al 2009;Suttle et al 2019;Pilgram et al 2022) their perturbative nature leads to questions about how reliably they can reconstruct the magnetic field in plasma flows. These experiments additionally tackle this question by careful comparison between numerical simulations and experimental data.…”

“…A simple way to quantify the perturbative effect of a probe is to calculate L probe /L plasma , where L probe is the probe size, and L plasma is the characteristic plasma size. In previous HEDP experiments, values of L probe /L plasma range from ∼0.1 (Suttle et al 2019;Pilgram et al 2022), to ∼ 0.05 (Everson et al 2009). In this paper, we use an inductive probe with a L probe /L plasma ∼ 1 mm/5 mm ∼ 0.2.…”

Two-Dimensional Thomson Scattering in Laser-Produced Plasmas

“…Measurements of the spatial variation of density and temperature in laser-produced plasmas (LPP) are crucial for the interpretation of laboratory experiments on perpendicular [8,9] and parallel [10,11] collisionless shocks [12,13] and related instabilities [14], diamagnetic cavities [15], magnetic reconnection [16], collisionless momentum transfer [17,18], artificial magnetospheres [19], or the generation of spontaneous magnetic fields via the Biermann battery [20,21]. However, with conventional Thomson scattering setups, only limited data points can be obtained for each configuration of the experiment.…”

First Results from the Thomson Scattering Diagnostic on the Large Plasma Device

“…The instrument has several advantages compared to other available diagnostics such as swept Langmuir probes [4], microwave interferometers [5], or selfemission spectroscopy [6,7], as it overcomes some of their limitations including model dependence, integration over the line-of-sight, or refraction at density gradients. Most importantly, TS allows measurements in transient plasmas with lifetimes of less than a microsecond, such as exploding laser-produced plasmas used in experiments on laboratoryscaled collisionless shocks [8,9], magnetospheres [10], ion-ion beam instabilities [11,12], diamagnetic cavities [13,14], magnetic reconnection [15], or magnetic field generation and amplification [16].…”