Implosion of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">D</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>temperature-controlled cryogenic foam targets with plastic ablators

Richard, A.; Tanaka, K. A.; Nishihara, Katsunobu; Nakai, M.; Katayama, M.; Fukuda, Y.; Kanabe, T.; Kitagawa, Yoneyoshi; Norimatsu, T.; Nakatsuka, Masahiro; Yamanaka, Tatsuhiko; Kado, M.; Kawashima, Takayuki; Chen, C.; Tsukamoto, Masahiro; Nakai, S.

doi:10.1103/physreve.49.1520

Cited by 9 publications

(7 citation statements)

References 13 publications

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“…The maximum x-ray emission takes place at the end of the maximum compression phase at the contact surface between the first and second layers just before it expands [6]. The minimum hot core radius is typically 24 p, m, close to the calculated contact surface radius; R -AR/2 = 18 p, m. The experimental convergence ratio was 12.4 at the contact surface.…”

supporting

confidence: 51%

“…, 15 K, could hardly produce either detectable protons or neutrons. Even for such could targets, however, x-ray streak cameras (XSC) and x-ray framing cameras (XFC) caught hot core images as reported [6], yielding hot core initial Fuel Temperature 6 is the core areal density from XSC and 7 from XFC.…”

mentioning

confidence: 96%

“…The foam layer contains a liquid or solid D2 fuel, making a hollow shell cryogenic fuel target [5,6]. The foam is made of trimethlylolpropanetrimethacrylate (typically H, 4C, OO4) of 10~1.3 p, m thickness and 220~28 mg/cm density (20% weight of solid plastics) and is coated with a 4 pm thick polyvinylphenol ablator, both to increase laser absorption and to reduce preheating [7].…”

mentioning

confidence: 99%

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Areal Density Measurement of Imploded Cryogenic Target by Energy Peak Shift of DD-Produced Protons

et al. 1995

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DD-produced protons are used to measure the imploded fuel-shell areal density pAR. Twelve green beams of the GEKKO XII laser directly imploded a cryogenic foam-shell target containing a liquid or solid D2 fuel. The proton emission is detected through a dipole magnet on a CR-39 plate, whose energy shift from 3.02 MeV yielded the maximum pAR of 10 mg/cm' or the density of 6 g/cm', in agreement with that from the secondary neutron method within a factor of 2. The proton energy spread is sensitive to the laser energy imbalance. PACS numbers: 52.70.Nc, 52.25.Tx, 52.50.Jm, 52.58.Ns If fuel is compressed to about 1000 times the DT liquid density and a central region is heated more than 5 keV during the final implosion stage, a fuel ignition and a net energy gain will occur. Directly driven targets have reached imploded density of 200 times the liquid DT with glass microballoons [1] and 600 times with plastic hollow shell targets [2]. A high gain target will be a cryogenic DT hollow shell with a central cavity [3]. Since a central cavity of the cryogenic target has no residual gases, it achieves high density compression.We are studying density and areal density of imploded cryogenic D2 targets. Very light plastic foam shell is used to help liquid or solid fuel make a uniform hollow shell. The secondary neutron method is used to determine the compressed density [4]. Neutrons from our cryogenic target, however, are few so we developed the other method to cross-check the areal density of the compressed shell. Fusion produced protons are used to measure the areal density.The target that we used is a low density plastic foam hollow shell sphere. The foam layer contains a liquid or solid D2 fuel, making a hollow shell cryogenic fuel target [5,6]. The foam is made of trimethlylolpropanetrimethacrylate (typically H, 4C, OO4) of 10~1.3 p, m thickness and 220~28 mg/cm density (20% weight of solid plastics) and is coated with a 4 pm thick polyvinylphenol ablator, both to increase laser absorption and to reduce preheating [7]. The shell radius is within RQ 303~24 p, m. The mass is 7.9~1.4 p, g. D2 density at 21 K is 170 mg/cm'. The target is sustained vertically with 7 p, m thick glass fiber at the center of the vacuum chamber and is cooled down to a presumed temperature in a retractable liquid-He-cooled shroud [8].Once D2 gas becomes liquid or solid in the foam layer, the shroud is retracted, and in 10 ms, 12 laser beams illuminate the target. At each exit of beams from the GEKKO XII system, there are a random phase plate and a single potassium dihydrogen phosphate crystal for second harmonics.The beams of 32 cm in diameter are focused in tetrahedral configuration on the target by f/3 15 asph. eric lenses. The focusing depth d/Ro = The total energy (527 nm) on target is from 3.5 to 12.1 kJ in 2.05~0.25 ns quasi-Hat-top pulse with 0.94~0.014 ns rise. Energy imbalance o ", between 12 beams is (3.7~1.7)% rms for all of the shots.In the final stage of implosion, a colder but denser main fuel-plastic mixed plasma layer (the second la...

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confidence: 51%

mentioning

confidence: 96%

mentioning

confidence: 99%

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Areal Density Measurement of Imploded Cryogenic Target by Energy Peak Shift of DD-Produced Protons

et al. 1995

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“…A deuterium and tritium mixture used as the fuel in these experiments are very difficult to control because it has cryogenic boiling and melting temperatures of about 19 K. High quality shells with foam layers inside act as a container for the tritium/deuterium mixture. [27][28][29][30][31] The foam layer on the inner surface of the capsule acts as a wick to make the cryogenic fuel disperse as uniformly as possible. Since the foam thickness is constant, the thickness of the cryogenic fuel remains at a constant thickness.…”

Section: Shell Structure Of Low Density Materialsmentioning

confidence: 99%

“…25,26 Additionally, low density foams have been utilized as a mold of cryogenic targets. [27][28][29][30][31] There have been several review papers on laser targets, [32][33][34][35][36] however, this paper is the first review focusing on low density materials used as laser targets. The authors believe that this review could be a good introduction to scientists that are starting to work in this field.…”

Section: Introductionmentioning

confidence: 99%

A review of low density porous materials used in laser plasma experiments

2018

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This review describes and categorizes the synthesis and properties of low density porous materials, which are commonly referred to as foams and are utilized for laser plasma experiments. By focusing a high-power laser on a small target composed of these materials, high energy and density states can be produced. In the past decade or so, various new target fabrication techniques have been developed by many laboratories that use high energy lasers and consequently, many publications and reviews followed these developments. However, the emphasis so far has been on targets that did not utilize low density porous materials. This review therefore, attempts to redress this balance and endeavors to review low density materials used in laser plasma experiments in recent years. The emphasis of this review will be on aspects of low density materials that are of relevance to high energy laser plasma experiments. Aspects of low density materials such as densities, elemental compositions, macroscopic structures, nanostructures, and characterization of these materials will be covered. Also, there will be a brief mention of how these aspects affect the results in laser plasma experiments and the constrictions that these requirements put on the fabrication of low density materials relevant to this field. This review is written from the chemists' point of view to aid physicists and the new comers to this field.

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Stimulated Raman scattering from symmetrically illuminated two-layered spherical targets with 527 nm laser light

et al. 1995

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Spectrally shifted Raman light with time was observed from two-layered spherical targets irradiated with 527 nm random phased laser light. The target was composed of a foam shell and an outer thin plastic layer. The Raman spectrum shifted rapidly to the short-wavelength side during the laser pulse. The start timing was earlier than that of the usually observed Raman light at an experiment with a single-layered plastic shell target. It was inferred that a plasma shoulder with a long scale length moved outward on the expanding plasma, consistent with the observed Raman light.

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Implosion ofD2temperature-controlled cryogenic foam targets with plastic ablators

Cited by 9 publications

References 13 publications

Areal Density Measurement of Imploded Cryogenic Target by Energy Peak Shift of DD-Produced Protons

Areal Density Measurement of Imploded Cryogenic Target by Energy Peak Shift of DD-Produced Protons

A review of low density porous materials used in laser plasma experiments

Stimulated Raman scattering from symmetrically illuminated two-layered spherical targets with 527 nm laser light

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