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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 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Potential impacts of liquid metal plasma facing components on heating and current drive actuators for a Fusion Nuclear Science Facility

This paper addresses the potential impact of liquid metal (LM) plasma facing components (PFCs) for the heating and current drive actuators (H&CD) on the Fusion Nuclear Science Facility (FNSF) fusion reactor. Fulfilling the high neutron fluence mission of the FSNF requires steady-state operation for extremely long pulses (months to years) between maintenance opportunities. The use of liquid metal as a surface material is one strategy for extending the lifetime of the PFCs for long pulse operation in a high heat flux, high neutron flux environment like that of the FNSF. Liquid metal PFCs provide possible pathways forward on many difficult aspects of a fusion reactor, however the LM PFCs also bring new challenges and unknowns with respect to the H&CD actuators needed to provide steady-state operation. The development of LM compatible materials for RF antennas will be critical, as well as strategies for minimizing contamination of antenna surfaces and the core plasma. Successful deployment of LM PFCs on the FNSF will require operational experience with RF in a liquid metal environment both on test stands and in an integrated toroidal environment.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Effect of boronization on plasma-facing graphite surfaces and its correlation with the plasma behavior in NSTX-U

Boronization is a Plasma Facing Component (PFC) conditioning technique widely used in tokamak machines. The National Spherical Torus Experiment-Upgrade (NSTX-U) applied this conditioning, using a plasma glow with a deuterated Trimethyl-boron (d-TMB) and He mixture. The use of boronization during the campaign improved the plasma performance, allowing longer plasma discharges and H-mode access. The chemical state of an ATJ graphite sample, used as a proxy for the NSTX-U PFCs, was monitored in-situ using the Materials Analysis Particle Probe (MAPP) diagnostic and X-ray Photoelectron Spectroscopy (XPS). The XPS data showed a progressive rise (from + fluence increased. Filterscopes were used to measure the light emitted by oxygen impurities in the plasma near the surface of the PFC. An increase in the registered magnitude of the OII line, normalized to the Dγ intensity, was observed as the concentration of O on the ATJ surface increased. The plasma performance was found to be strongly correlated to oxygen impurity concentrations at the plasma edge and on the PFC surface, as measured by the discharge length and access to the H-mode regime. In this work, we present a quantitative analysis of the evolution of the chemistry of the ATJ surface, and the oxygen presence in the plasma-material interface, and report relevant plasma parameters observed during the same period of time.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗