Raster Thomson scattering in large-scale laser plasmas produced at high repetition rate

Kaloyan, Marietta; Ghazaryan, Sofiya; Constantin, Carmen; Dorst, R. S.; Heuer, Peter; Pilgram, Jessica; Schaeffer, D. B.; Niemann, C.

doi:10.1063/5.0059244

Cited by 10 publications

(8 citation statements)

References 28 publications

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“…A notch mask is placed in between the double-subtractive spectrometers to remove light at λ i . A 0.75 mm wide and 50 µm thick stainless steel mask blocks a wavelength range of 1.5 nm with an extinction ratio of 2.0 ×10 4 integrated over the entire spectrum [30,31]. The notch mask also acts to reduce the intensity of the broad Lorentzian wings of the instrument-broadened laser line outside of the 1.5 nm blocking width, since the 532 nm signal is removed before light reaches and scatters off of the second and third gratings (DG2 and DG3).…”

Section: Methodsmentioning

confidence: 99%

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

et al. 2022

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We present the first Thomson scattering measurements of electron density and temperature in the Large Plasma Device (LAPD), a 22 m long magnetized linear plasma device at the University of California Los Angeles (UCLA). The diagnostic spectrally resolves the Doppler shift imparted on light from a frequency-doubled Nd:YAG laser when scattered by plasma electrons. A fiber array coupled to a triple-grating spectrometer is used to obtain high stray light rejection and discriminate the faint scattering signal from a much larger background. In the center of the plasma column, the measured electron density and temperature are about ne≈1.5×1013 cm−3 and Te≈ 3 eV, respectively, depending on the discharge parameters and in good agreement with Langmuir probe data. Optical design considerations to maximize photon count while minimizing alignment sensitivity are discussed in detail and compared to numerical calculations. Raman scattering off of a quartz crystal probe is used for an absolute irradiance calibration of the system.

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Section: Methodsmentioning

confidence: 99%

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

et al. 2022

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“…The small secondary laser plasma created by this probe laser reaches the B-dot probe and Thomson scattering volume hundreds of ns after the time of data collection and thus does not affect the results. A detailed description of the Thomson scattering setup and measurements has been published separately [ 35 ] .…”

Section: Experimental Designmentioning

confidence: 99%

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

Pilgram

Adams

Constantin

et al. 2022

High Pow Laser Sci Eng

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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.

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Section: Experimental Designmentioning

confidence: 99%

“…In a forthcoming companion paper we perform an intensity calibration to match a subset of the experimental results and use the remaining data to validate the simulations. We have developed a campaign to validate against both the velocity and the magnetic fields as captured by the 10-J-drive case, but also the plasma properties using the 5-J-drive Thomson data 37 , as they provide more validation points. From there we can initiate a double-blind test in order to determine if FLASH can predict experimentally obtained values.…”

Section: Numerical Modeling With Flashmentioning

confidence: 99%

High Repetition Rate Exploration of the Biermann Battery Effect in Laser Produced Plasmas Over Large Spatial Regions

Pilgram,

Adams,

Constantin

et al. 2021

Preprint

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Self-generated magnetic fields occur in astrophysical systems throughout our universe. The Biermann battery is one possible source of such magnetic fields. This effect is caused by non-parallel temperature and density gradients within a plasma, represented in the magnetohydrodynamic framework by the baroclinic term in the induction equation, c en e ∇T e × ∇n e . In this paper we present a high repetition rate laboratory astrophysics experiment 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 the millimeter scale, by measuring fields spatially at approximately 1.0 centimeter and larger. Our measurements show azimuthally symmetric magnetic fields with peak values of 60 G in our closest measurements, 0.7 cm from the target surface. Optical Thomson scattering measurements give values for the electron temperature and density of the laser produced plasma (LPP) on axis, of T e = 10 ± 2 eV, and (5.5 ± 1) × 10 16 cm −3 , respectively. The velocity of the LPP's front has been estimated to be ∼ 330 km s −1 by measuring the time and position of the maximum magnetic fields measured. The expansion rate of the magnetic fields, and current density within the system are also mapped and examined. Furthermore, we have initiated a simulation campaign using the FLASH code to determine the veracity of the Biermann mechanism in our experiments, as well as the plasma's characteristics.

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Raster Thomson scattering in large-scale laser plasmas produced at high repetition rate

Cited by 10 publications

References 28 publications

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

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

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

High Repetition Rate Exploration of the Biermann Battery Effect in Laser Produced Plasmas Over Large Spatial Regions

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