K-shell radiation physics in low- to moderate-atomic-number z-pinch plasmas on the Z accelerator

Jones, B.; Deeney, C.; Coverdale, C. A.; LePell, P.D.; McKenney, J. L.; Apruzese, J. P.; Thornhill, J. W.; Whitney, K. G.; Clark, Robert W.; Velikovich, A. L.; Davis, J.; Maron, Y.; Kantsyrev, V.L.; Safronova, A.S.; Oreshkin, V. I.

doi:10.1016/j.jqsrt.2005.05.027

Cited by 64 publications

(14 citation statements)

References 26 publications

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“…The present analysis is likely relevant to high-current implosions, like z-pinch experiments on the Z machine [46]. Indeed, based on the plasma parameters given in [7], Re is also high (∼ 10 4 ), and M is similar to the case analyzed here.…”

Section: Experimental Datasupporting

confidence: 59%

Turbulent stagnation in a Z -pinch plasma

et al. 2018

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The ion kinetic energy in a stagnating plasma was previously determined by Kroupp et al. [Phys. Rev. Lett. 107, 105001 (2011)PRLTAO0031-900710.1103/PhysRevLett.107.105001] from Doppler-dominated line shapes augmented by measurements of plasma properties and assuming a uniform-plasma model. Notably, the energy was found to be dominantly stored in hydrodynamic flow. Here we advance a new description of this stagnation as supersonically turbulent. Such turbulence implies a nonuniform density distribution. We demonstrate how to reanalyze the spectroscopic data consistent with the turbulent picture and show that this leads to better concordance of the overconstrained spectroscopic measurements, while also substantially lowering the inferred mean density.

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Section: Experimental Datasupporting

confidence: 59%

Turbulent stagnation in a Z -pinch plasma

et al. 2018

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“…[29][30][31][32], and references therein) have been consistently successful in predicting the radiative yields and guiding the load design. 33 The same can be said about predicting K-shell yields from, and guiding the design of, Ne and Ar gas-puff Z pinches, [34][35][36] as well as prediction of thermal neutron yields from deuterium gas-puff Z-pinch loads. [37][38][39] Very recently, Maron et al 40 found good agreement between a 1D analytical shock model and experimental data obtained both in $0.5 MA gas-puff implosions observed at the Weizmann Institute of Science and in $20 MA wire-array implosions at Sandia National Laboratories.…”

Section: Introductionmentioning

confidence: 99%

Application of one-dimensional stagnation solutions to three-dimensional simulation of compact wire array in absence of radiation

Velikovich

Maron

2014

Physics of Plasmas

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We investigate the stagnation phase of a three-dimensional (3D), magnetohydrodynamic simulation of a compact, tungsten wire-array Z pinch, under the simplifying assumption of negligible radiative loss. In particular, we address the ability of one-dimensional (1D) analytic theory to describe the time evolution of spatially averaged plasma properties from 3D simulation. The complex fluid flows exhibited in the stagnated plasma are beyond the scope of 1D theory and result in centrifugal force as well as enhanced thermal transport. Despite these complications, a 1D homogeneous (i.e., shockless) stagnation solution can capture the increase of on-axis density and pressure during the initial formation of stagnated plasma. Later, when the stagnated plasma expands outward into the imploding plasma, a 1D shock solution describes the decrease of on-axis density and pressure, as well as the growth of the shock accretion region. V

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“…Wire arrays for producing K-shell x-rays are typically larger diameter than the compact ICF loads, placing the mass at large initial diameter so that high implosion velocities and thus plasma temperatures can be achieved for ionizing to the K shell [18]. It is arguably even less intuitive that planar wire arrays would benefit K-shell x-ray production, as the mass is radially distributed rather than initiated at large diameter, but this is another topic that can be addressed on Saturn.…”

Section: Chapter 1 Introductionmentioning

confidence: 99%

Compact wire array sources: power scaling and implosion physics.

Serrano¹,

Chuvatin

Jones³

et al. 2008

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A series of ten shots were performed on the Saturn generator in short pulse mode in order to study planar and small-diameter cylindrical tungsten wire arrays at ∼5 MA current levels and 50-60 ns implosion times as candidates for compact z-pinch radiation sources. A new vacuum hohlraum configuration has been proposed in which multiple z pinches are driven in parallel by a pulsed power generator. Each pinch resides in a separate return current cage, serving also as a primary hohlraum. A collection of such radiation sources surround a compact secondary hohlraum, which may potentially provide an attractive Planckian radiation source or house an inertial confinement fusion fuel capsule. Prior to studying this concept experimentally or numerically, advanced compact wire array loads must be developed and their scaling behavior understood. The 2008 Saturn planar array experiments extend the data set presented in Ref.[1], which studied planar arrays at ∼3 MA, 100 ns in Saturn long pulse mode. Planar wire array power and yield scaling studies now include current levels directly applicable to multi-pinch experiments that could be performed on the 25 MA Z machine. A maximum total x-ray power of 15 TW (250 kJ in the main pulse, 330 kJ total yield) was observed with a 12-mm-wide planar array at 5.3 MA, 52 ns. The full data set indicates power scaling that is sub-quadratic with load current, while total and main pulse yields are closer to quadratic; these trends are similar to observations of compact cylindrical tungsten arrays on Z. We continue the investigation of energy coupling in these short pulse Saturn experiments using zero-dimensional-type implosion modeling and pinhole imaging, indicating 16 cm/μs implosion velocity in a 12-mm-wide array. The same phenomena of significant trailing mass and evidence for resistive heating are observed at 5 MA as at 3 MA. 17 kJ of Al K-shell radiation was obtained in one Al planar array fielded at 5.5 MA, 57 ns and we compare this to cylindrical array results in the context of a K-shell yield scaling model. We have also performed an initial study of compact 3 mm diameter cylindrical wire arrays, which are alternate candidates for a multi-pinch vacuum hohlraum concept. These massive 3.4 and 6 mg/cm loads may have been impacted by opacity, producing a maximum x-ray power of 7 TW at 4.5 MA, 45 ns. Future research directions in compact x-ray sources are discussed. 4 AcknowledgmentWe thank M. Lopez (1675), G. T. Liefeste (1675), and J. L. Porter (1670) for providing load hardware and diagnostic support; L.B. Nielsen-Weber (1675) and D.S. Nielsen (1675) for extensive support of diagnostic installation, fielding, and film processing;

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K-shell radiation physics in low- to moderate-atomic-number z-pinch plasmas on the Z accelerator

Cited by 64 publications

References 26 publications

Turbulent stagnation in a Z -pinch plasma

Turbulent stagnation in a Z -pinch plasma

Application of one-dimensional stagnation solutions to three-dimensional simulation of compact wire array in absence of radiation

Compact wire array sources: power scaling and implosion physics.

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