Tungsten wire-array Z-pinch experiments at 200 TW and 2 MJ

Spielman, R. B.; Deeney, C.; Chandler, G. A.; Douglas, M. R.; Fehl, D. L.; Matzen, M. K.; McDaniel, D. H.; Nash, T. J.; Porter, J. L.; Sanford, T.W.L.; Seamen, J. F.; Stygar, W. A.; Struve, K.W.; Breeze, S. P.; McGurn, J.; Torres, J. A.; Žagar, Drago; Gilliland, T. L.; Jobe, D.; McKenney, J. L.; Mock, R. C.; Vargas, M.; Wagoner, T. C.; Peterson, Darrell L.

doi:10.1063/1.872881

Cited by 574 publications

(180 citation statements)

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“…(10) and (11) reveals that l a=b s scales inversely with n b . This is most likely to be the scaling that causes the change in the collisionality observed in the 16 wire array data in Fig.…”

Section: -9mentioning

confidence: 99%

“…6,7 Once the wires are broken the array undergoes a snowplough like implosion, 8,9 followed by the stagnation of the accrued kinetic energy as an intense pulse of soft x-ray radiation. 10,11 This paper presents the results of a series of experiments conducted in order to investigate the dynamics of wire array plasmas during the ablation phase. In particular, it focuses on the azimuthal ablation flow structures formed in aluminium wire arrays.…”

Section: Introductionmentioning

confidence: 99%

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Oblique shock structures formed during the ablation phase of aluminium wire array z-pinches

et al. 2013

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A series of experiments has been conducted in order to investigate the azimuthal structures formed by the interactions of cylindrically converging plasma flows during the ablation phase of aluminium wire array Z pinch implosions. These experiments were carried out using the 1.4 MA, 240 ns MAGPIE generator at Imperial College London. The main diagnostic used in this study was a two-colour, end-on, Mach-Zehnder imaging interferometer, sensitive to the axially integrated electron density of the plasma. The data collected in these experiments reveal the strongly collisional dynamics of the aluminium ablation streams. The structure of the flows is dominated by a dense network of oblique shock fronts, formed by supersonic collisions between adjacent ablation streams. An estimate for the range of the flow Mach number (M ¼ 6.2-9.2) has been made based on an analysis of the observed shock geometry. Combining this measurement with previously published Thomson Scattering measurements of the plasma flow velocity by Harvey-Thompson et al. [Physics of Plasmas 19, 056303 (2012)] allowed us to place limits on the range of the ZT e of the plasma. The detailed and quantitative nature of the dataset lends itself well as a source for model validation and code verification exercises, as the exact shock geometry is sensitive to many of the plasma parameters. Comparison of electron density data produced through numerical modelling with the Gorgon 3D MHD code demonstrates that the code is able to reproduce the collisional dynamics observed in aluminium arrays reasonably well. V C 2013 American Institute of Physics. [http://dx

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Section: -9mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Oblique shock structures formed during the ablation phase of aluminium wire array z-pinches

et al. 2013

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“…Experiments on the 20 MA Z pulsed power generator [1] have achieved peak powers of 280-300 TW with a >2 MJ yield at 20% efficiency [2] by imploding cylindrical arrays consisting of hundreds of fine metallic wires. It was found [3][4] [5] that in wire array Z pinches the wires remain stationary for the first 60-80% of the implosion time and steadily ablate plasma which is accelerated by the j×B force.…”

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confidence: 99%

Optical Thomson Scattering Measurements of Plasma Parameters in the Ablation Stage of Wire ArrayZPinches

et al. 2012

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A Thomson scattering diagnostic has been used to measure the parameters of cylindrical wire array Z pinch plasmas during the ablation phase. The scattering operates in the collective regime (α>1) allowing spatially localised measurements of the ion or electron plasma temperatures and of the plasma bulk velocity. The ablation flow is found to accelerate towards the axis reaching peak velocities of 1.2-1.3×10 7 cm/s in aluminium and ∼1×10 7 cm/s in tungsten arrays. Precursor ion temperature measurements made shortly after formation are found to correspond to the kinetic energy of the converging ablation flow.Wire array Z pinch implosions can efficiently convert stored electrical energy into powerful bursts of soft xrays. Experiments on the 20 MA Z pulsed power generator [1] have achieved peak powers of 280-300 TW with a >2 MJ yield at 20% efficiency [2] by imploding cylindrical arrays consisting of hundreds of fine metallic wires. It was found [3][4][5] that in wire array Z pinches the wires remain stationary for the first 60-80% of the implosion time and steadily ablate plasma which is accelerated by the j×B force. This ablation flow distributes mass in the array interior which sets the initial conditions for the implosion phase. The ablation mass distribution depends on the ablation rate, dm/dt, and on the flow velocity, which are related via force -momentum balance. However, the flow velocity was not measured in past experiments apart from the velocity of the initial part of the flow which was inferred from the time of plasma appearance on the array axis and from end-on interferometry measurements, giving V∼1.5×10 7 cm/s [6] [7]. The velocity of the ablation flow in the later stages, when the majority of the ablated material is moving into the array interior, is not known. Instead, the ablation rate and mass redistribution is often discussed using the so-called 'ablation velocity', introduced in the rocket model [3] via momentum balance arguments, which is inferred from the implosion dynamics or from unfolds of x-ray radiography measurements of mass distribution in the array interiorNumerical simulations [10][11] show that velocity is changing both with time and with the radial position of the flow, indicating that the flow is accelerated by the j×B force acting on the plasma in the array interior. However, these simulations do not model the initial heating of the wires and the process of conversion of initially cold metallic wires into a plasma. Instead, simulations start from wire material already converted into plasma at some initial temperature and density, and these initial conditions are adjusted to produce agreement of the simulated implosion dynamics with experimental observations. Direct measurements of the ablation flow velocity and density are needed to allow verification of these numerical models. Knowledge of the flow velocity is also important for other applications of different wire array Z pinch configurations, used e.g. in laboratory astrophysics [12] and other HEDP basic science research.In th...

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“…This wire-number dkcovery represented a breakthrough (1O, 11) in controlling z-pinch instabilities and was a major step forward in z-pinch load design for large pulsed- power generators [12][13][14][15]. Combined with the conversion of the PBFA-11generator to a z-pinch driver [7], the successful application of this breakthrough on Z [16] reopened interest in the field of fast z-pinches [17] as xray sources for fbsion [18,19]. At Sandia National Laboratories, for example, three hohlraum concepts that take advantage of the high x-ray powers generated with thk new pulsed-power capability are under development to investigate the feasibility of z-pinches to drive ICF targets [18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

“…research facilities -the Omega laser at the University of Rochester [6] and the Zfacility at Sandia National Laboratories [7] -are currently employed in pre-NIF hohlraum experiments to test various aspects of the indirect-drive ICF concept. The Omega hohlraums are used to generate high-temperature short-pulses in small-scale hohlraums, while Z can be used for complementary studies involving lower-temperature longerpulses in full NfF-scale hohlraums.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of a Z-pinch x-ray source for heating inertial-confinement-fusion relevant hohlraums to 120–160 eV

et al. 2000

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JU@ /-72&')(j 0s7/ 'AbstractA z-pinch radiation source has been developed that generates 6W20 lc.1of x-rays with a peak power of 13*4 TW through a 4-mm diameter axial aperture on the Z facility. The source has heated ND? (National Ignition Facility)-scale (6-mm diameter by 7-mm high) hohlraums to 122&6 eV and reduced-scale (4-mm diameter by 4-mm high) hohlraurns to 155*8 eV --providing environments suitable for indirect-drive ICF (Inertial Confinement Fusion) studies.Eulerian-RMHC (radiation-hydrodynamics code) simulations that take into account the development of the Rayleigh-Taylor instability in the r-z plane provide integrated calculations of the implosion, x-ray generation, and hohlraurn heating, as well as estimates of wall motion and plasma fill within the hohlraums. Lagrangian-RMHC simulations su'ggestthat the addition of a 6 mg/cm3 C~fill in the reduced-scale hohlraum decreases hohlmum inner-wall velocity by -40% with only a 3-5 % decrease in peak temperature, in agreement with measurements.

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Tungsten wire-array Z-pinch experiments at 200 TW and 2 MJ

Cited by 574 publications

References 9 publications

Oblique shock structures formed during the ablation phase of aluminium wire array z-pinches

Oblique shock structures formed during the ablation phase of aluminium wire array z-pinches

Optical Thomson Scattering Measurements of Plasma Parameters in the Ablation Stage of Wire ArrayZPinches

Dynamics of a Z-pinch x-ray source for heating inertial-confinement-fusion relevant hohlraums to 120–160 eV

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