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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 955 records · Page 53
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Multimodal Options for Materials Research to Advance the Basis for Fusion Energy in the ITER Era

Well-coordinated international fusion materials research on multiple fundamental feasibility issues can serve an important role during the next ten years. An overview is given of the current state-of-the-art of major materials systems that are candidates for next-step fusion reactors, including a summary of existing knowledge regarding operating temperature and neutron irradiation fluence limits due to high temperature strength and radiation damage considerations, coolant compatibility information, and current industrial manufacturing capabilities. There are two inter-related overarching objectives of fusion materials research to be performed in the next decade: 1) understanding materials science phenomena in the demanding DT fusion energy environment, and 2) Using this improved understanding to develop and qualify materials to provide the basis for next-step facility construction authorization by funding agencies and public safety licensing authorities. The critical issues and prospects for development of high performance fusion materials are discussed along with recent research results and planned activities of the international materials research community.

Zinkle, Steven J↗
DOE OSTI2017

Gyrokinetic projection of the divertor heat-flux width from present tokamaks to ITER

Here, the XGC1 edge gyrokinetic code is used to study the width of the heat-flux to divertor plates in attached plasma condition. The flux-driven simulation is performed until an approximate power balance is achieved between the heat-flux across the steep pedestal pressure gradient and the heat-flux on the divertor plates.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

Investigation into the formation of the scrape-off layer density shoulder in JET ITER-like wall L-mode and H-mode plasmas

The low temperature boundary layer plasma (scrape-off layer or SOL) between the hot core and the surrounding vessel determines the level of power loading, erosion and implantation of material surfaces, and thus the viability of tokamak-based fusion as an energy source. Here, this study explores mechanisms affecting the formation of flattened density profiles, so-called 'density shoulders', in the low-field side (LFS) SOL, which modify ion and neutral fluxes to surfaces—and subsequent erosion. There is evidence against local enhancement of ionization inducing shoulder formation. We find that increases in SOL parallel resistivity, Λ div (=[ L || ν ei Ω i ]/ c s Ω e ), postulated to lead to shoulder growth through changes in SOL turbulence characteristics, correlates with increases in SOL shoulder amplitude, A s , but only under a subset of conditions (D 2 -fuelled L-mode density scans with outer strike point on the horizontal target). Λ div fails to correlate with A s for cases of N 2 seeding or during sweeping of the strike point across the horizontal target. The limited correlation of Λ div and A s is also found for H-mode discharges. Thus, while it may be necessary for Λ div to be above a threshold of ~1 for shoulder formation and/or growth, another mechanism is required. More significantly, we find that in contrast to parallel resistivity, outer divertor recycling, as quantified by the total outer divertor Balmer D α emission, I – D α , does scale with A s where Λ div does and even where Λ div does not. Divertor recycling could lead to SOL density shoulder formation through: (a) reducing the parallel to the field flow (loss) of ions out of the SOL to the divertor; and (b) changes in radial electric fields which lead to E × B poloidal flows as well as potentially affecting SOL turbulence birth characteristics. Therefore, changes in divertor recycling may be the sole process involved in bringing about SOL density shoulders or it may be that it acts in tandem with parallel resistivity.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗