Fully Kinetic Particle-in-Cell Simulations of a Deuterium Gas Puff<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>z</mml:mi></mml:math>Pinch

Welch, D. R.; Rose, D. V.; Clark, Robert E.; Mostrom, C. B.; Stygar, W. A.; Leeper, R. J.

doi:10.1103/physrevlett.103.255002

Cited by 41 publications

(18 citation statements)

References 14 publications

(19 reference statements)

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“…In 15 MA experiments, the dominant mechanism for fusion has been shown to be thermonuclear [12]. Estimations of the fractional yield by thermonuclear fusion from fully kinetic simulations of gas puff pinches by Welch et al [13] support this hypothesis.…”

supporting

confidence: 58%

“…In the kinetic phase, simulations require that the electron gyro-frequency be resolved (∆t < 10 − 100 fs) for stability. The kinetic phase of the simulations closely followed the fully kinetic simulations in Welch et al [13], and specific details of the computational setup for this work are described therein. Use of the hybrid model substantially reduced the computational time required, enabling a thorough study to be performed.…”

mentioning

confidence: 99%

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Transition from Beam-Target to Thermonuclear Fusion in High-Current DeuteriumZ-Pinch Simulations

et al. 2016

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supporting

confidence: 58%

mentioning

confidence: 99%

Transition from Beam-Target to Thermonuclear Fusion in High-Current DeuteriumZ-Pinch Simulations

et al. 2016

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“…For the reasons discussed in the last paragraph of Sec. V, it would be of interest to couple TL to a 2D or 3D magnetohydrodynamic (MHD) or PIC model of a z-pinch load [69][70][71][72][73][74], which would calculate more accurately the time-dependent pinch inductance. Present MHD and PIC codes use a highly idealized accelerator-circuit model to drive a pinch implosion; in principle, it is possible to replace such a model with a more complete TL model.…”

Section: Discussion and Suggestions For Future Workmentioning

confidence: 99%

55-TW magnetically insulated transmission-line system: Design, simulations, and performance

Stygar¹,

Corcoran²,

Ives³

et al. 2009

Phys. Rev. ST Accel. Beams

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We describe herein a system of self-magnetically insulated vacuum transmission lines (MITLs) that operated successfully at 20 MA, 3 MV, and 55 TW. The system delivered the electromagnetic-power pulse generated by the Z accelerator to a physics-package load on over 1700 Z shots. The system included four levels that were electrically in parallel. Each level consisted of a water flare, vacuum-insulator stack, vacuum flare, and 1.3-m-radius conical outer MITL. The outputs of the four outer MITLs were connected in parallel by a 7.6-cm-radius 12-post double-post-hole vacuum convolute. The convolute added the currents of the four outer MITLs, and delivered the combined current to a single 6-cm-long inner MITL. The inner MITL delivered the current to the load. The total initial inductance of the stack-MITL system was 11 nH. A 300-element transmission-line-circuit model of the system has been developed using the TL code. The model accounts for the following: (i) impedance and electrical length of each of the 300 circuit elements, (ii) electron emission from MITL-cathode surfaces wherever the electric field has previously exceeded a constant threshold value, (iii) Child-Langmuir electron loss in the MITLs before magnetic insulation is established, (iv) MITL-flow-electron loss after insulation, assuming either collisionless or collisional electron flow, (v) MITL-gap closure, (vi) energy loss to MITL conductors operated at high lineal current densities, (vii) time-dependent self-consistent inductance of an imploding z-pinch load, and (viii) load resistance, which is assumed to be constant. Simulations performed with the TL model demonstrate that the nominal geometric outer-MITL-system impedance that optimizes overall performance is a factor of $3 greater than the convolute-load impedance, which is consistent with an analytic model of an idealized MITL-load system. Power-flow measurements demonstrate that, until peak current, the Z stack-MITL system performed as expected. TL calculations of the peak electromagnetic power at the stack, stack energy, stack voltage, outer-MITL current, and load current, as well as the pinch-implosion time, agree with measurements to within 5%. After peak current, TL calculations and measurements diverge, which appears to be due in part to the idealized pinch model assumed by TL. The results presented suggest that the design of the Z accelerator's stack-MITL system, and the TL model, can serve as starting points for the design of stack-MITL systems of future superpower accelerators.

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“…24) and particle-in-cell (Ref. 25) simulations showed that there is a hope of a large thermonuclear component but only a few experimental results were accumulated during several shots.…”

Section: Introductionmentioning

confidence: 98%

Deuterium gas puff Z-pinch at currents of 2 to 3 mega-ampere

et al. 2012

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Deuterium gas-puff experiments have been carried out on the GIT-12 generator at the Institute of High Current Electronics in Tomsk. The emphasis was put on the study of plasma dynamics and neutron production in double shell gas puffs. A linear mass density of deuterium (D2) varied between 50 and 85 μg/cm. Somewhat problematic was a spread of the D2 gas at a large diameter in the central anode–cathode region. The generator operated in two regimes, with and without a plasma opening switch (POS). When the POS was used, a current reached a peak of 2.7 MA with a 200 ns rise time. Without the POS, a current rise time approached 1500 ns. The influence of different current rise times on neutron production was researched. Obtained results were important for comparison of fast deuterium Z-pinches with plasma foci. Average DD neutron yields with and without the POS were about 1011. The neutron yield seems to be dependent on a peak voltage at the Z-pinch load. In all shots, the neutron emission started during stagnation. At the beginning of the neutron production, the neutron emission correlated with soft x-rays and a significant fraction of neutrons could be explained by the thermonuclear mechanism. Nevertheless, a peak of the neutron emission occurred 40 ns after a soft x-ray peak. At this very moment, hard x-rays above 1 MeV were detected and a rapid expansion with a velocity of 3×105 m/s was observed. In the case of the POS, 1 MeV widths of radial neutron spectra implied that there are deuterons with the energy above 200 keV moving in the radial direction. On the basis of D2 gas puff experiments in the 0.3–17 MA region, the neutron yield dependence on a current as Y∝I3.0±0.2 was proposed.

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Fully Kinetic Particle-in-Cell Simulations of a Deuterium Gas PuffzPinch

Cited by 41 publications

References 14 publications

Transition from Beam-Target to Thermonuclear Fusion in High-Current DeuteriumZ-Pinch Simulations

Transition from Beam-Target to Thermonuclear Fusion in High-Current DeuteriumZ-Pinch Simulations

55-TW magnetically insulated transmission-line system: Design, simulations, and performance

Deuterium gas puff Z-pinch at currents of 2 to 3 mega-ampere

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