Mechanical Properties of Thin GDP Shells Used as Cryogenic Direct Drive Targets at OMEGA

Nikroo, A.; Czechowicz, D. G.; Chen, K. C.; Dicken, Matthew J.; Andrews, R.; Greenwood, A.; Castillo, E. R.

doi:10.13182/fst45-2-229

Cited by 14 publications

(7 citation statements)

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“…Over the same period, there have been key advances in the production of highly-polarized H and D, driven by Nuclear and Particle Physics (NP) experiments [14][15][16], as well as in the production of hyper-polarized 3 He gas for use both as a contrast agent in medical imaging [17][18][19] and in high-energy spin physics. ICF polymer shell technology has also been developed [20], and can now be used to contain polarized fuel (section 5). Finally, cryogenic injection guns have been demonstrated to convey pellets into the core of tokamak plasmas with high efficiencies [21].…”

Section: Introductionmentioning

confidence: 99%

Polarized fusion and potential in situ tests of fuel polarization survival in a tokamak plasma

et al. 2023

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The use of spin-polarized fusion fuels would provide a significant boost towards the ignition of a burning plasma. The cross section for D+T→ α+n, would be increased by 1.5 if the fuels were injected with parallel polarization. Furthermore, our simulations demonstrate additional non-linear power gains in large-scale machines such as ITER, due to increased alpha heating. Such benefits require the survival of spin polarizations for periods comparable to the particle confinement time. During the 1980s, calculations predicted that polarizations could survive a plasma environment, although concerns persisted regarding the cumulative impacts of wall recycling. In that era, technical challenges prevented direct tests and left the large scale fueling of a power reactor beyond reach. Over the last decades, this situation has dramatically changed. Detailed simulations of ITER have predicted negligible wall recycling in a high-power reactor, and recent advances in laser-driven sources project the capability of producing large quantities of ~100% polarized D and T. The remaining crucial step is an in-situ demonstration of polarization survival in a plasma. For this, we outline a measurement strategy using the isospin-mirror reaction, D+3He→ α+p. Polarized 3He avoids the complexities of handling tritium, while encompassing the same spin-physics. We evaluate two methods of delivering deuterium, using dynamically polarized Lithium-Deuteride (with vector polarization PV D of 70%) or frozen-spin Hydrogen-Deuteride (with PV D of 40%), together with a method of injecting optically-pumped 3He (with 65% polarization). Pellets of these materials all have long polarization decay times (~6 minutes for LiD at 2K, ~2 months for HD at 2K, and ~3 days for 3He at 77K), all far greater than a plasma shot in a research tokamak such as DIII-D. Both species can be propelled from a single cryogenic injection gun. We review plasma requirements and strategies for detecting polarization survival. Polarization alters both fusion yields and the angular distribution of fusion products, and each of these provides a potential signal. In this paper we simulate a selection of shots with similar characteristics in a future high-Tion H plasma, and find ratios of yields from shots with fuel spins parallel and antiparallel reaching 1.3 (HD+3He) to 1.6 (LiD+3He) over a wide range of poloidal angles. (A companion paper finds sensitivity to fusion product angular distributions as reflected in the pitch angles of protons and alphas reaching the plasma facing wall.)

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Section: Introductionmentioning

confidence: 99%

Polarized fusion and potential in situ tests of fuel polarization survival in a tokamak plasma

et al. 2023

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“…For these reasons, and the lack of capabilities to build high density carbon (HDC) capsules of the desired size at the time, we based our point design on glow discharge polymer (GDP) ablators, which necessitated capsules of ∼20 µm thickness for the desired fill pressure. [5] The initial shots were thus fielded using 3 mm diameter GDP capsules with thicknesses of 18-20 µm and ∼8 atm gas fill. The inflight implosion self-emission measurements and post-shot simulations from these initial shots (N160920-003, N160920-005, N160921-001, N170212-003, and N170212-004) indicated slight inflight asymmetry early in the implosion and a very asymmetric shell at bang time.…”

Section: Introductionmentioning

confidence: 99%

“…Such an ablator could potentially enable the use of a shorter pulse, and the higher thermal conductivity of a higher density material could help to mitigate the nonuniformity of the laser energy deposition. Due to the linear relation between tensile strength and capsule burst pressure, [5] materials such as boron (B), high density carbon (HDC), boron carbide (B 4 C), and boron nitride (BN), which have tensile strength 5-10 times higher than that of GDP, could presumably support the 8-10 atm fill pressures of the nominal PDXP point design at substantially reduced thickness relative to GDP. While HDC is now a common capsule material, our interest in boron-containing materials is motivated by the possibility of collecting data to help constrain simulation models of the PDXP platform.…”

Section: Introductionmentioning

confidence: 99%

Comparison of ablators for the polar direct drive exploding pusher platform

Whitley,

Kemp,

Yeamans

et al. 2020

Preprint

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We examine the performance of pure boron, boron carbide, high density carbon, and boron nitride ablators in the polar direct drive exploding pusher (PDXP) platform. The platform uses the polar direct drive configuration at the National Ignition Facility to drive high ion temperatures in a room temperature capsule and has potential applications for plasma physics studies and as a neutron source. The higher tensile strength of these materials compared to plastic enables a thinner ablator to support higher gas pressures, which could help optimize its performance for plasma physics experiments, while ablators containing boron enable the possiblity of collecting addtional data to constrain models of the platform. Applying recently developed and experimentally validated equa-$ Manuscript prepared for the proceedings of IFSA2019.

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“…The glow discharge polymer (GDP) films have the properties of low atomic number, low density, and superior optical property, as well as the ability to effectively reduce the Rayleigh‐Taylor instability of mixed interface caused by the superthermal electrons in inertial confinement fusion (ICF) experiments . In view of these advantages, the GDP films have been widely used as the major nominal ablator material in ICF experiments .…”

Section: Introductionmentioning

confidence: 99%

Chemical structure and surface morphology evolution of glow discharge polymer films by Ar‐ions intermittent etching

Zhang

Chen

et al. 2018

Surface & Interface Analysis

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The Ar-ions intermittent-etching technique was successfully incorporated during the deposition of glow discharge polymer (GDP) films. The ionic components and ion energy distributions (IEDs) of C 4 H 8 /H 2 and C 4 H 8 /H 2 /Ar plasma were diagnosed by an energy-resolved mass spectrometer, respectively. The Fourier transform infrared spectroscopy, scanning electron microscope, and white-light interferometer were used to studying the chemical structure, surface morphology, and roughness of the GDP films, which are deposited with the various time of Ar-ions intermittent etching. With the introduction of Ar into the chamber, the intensity of the C-H absorption peaks becomes weak and the large-mass C-H species were ionized and dissociated from the mass spectrometer results. The surface roughness of GDP films are decreased with Ar-ions intermittent etching, the lowest surface roughness (Rq) is only 33.6 nm when the intermittent cycle is 60 minutes/15 minutes. The highest sp 3 CH 3 (sym) absorption peaks are attributed to samples also with 60-minute/15-minute intermittent cycle, which shortens the length of the carbon chain and reduces the probability of the cluster formations.

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Mechanical Properties of Thin GDP Shells Used as Cryogenic Direct Drive Targets at OMEGA

Abstract: Thin glow discharge polymer (GDP)

Cited by 14 publications

References 0 publications

Polarized fusion and potential in situ tests of fuel polarization survival in a tokamak plasma

Polarized fusion and potential in situ tests of fuel polarization survival in a tokamak plasma

Comparison of ablators for the polar direct drive exploding pusher platform

Chemical structure and surface morphology evolution of glow discharge polymer films by Ar‐ions intermittent etching

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