Effect of boronization on ohmic plasmas in NSTX

Skinner, C.H.; Kugel, H.; Maingi, R.; Wampler, W.R.; Blanchard, W.; Bell, M.G.; Bell, R.E.; Gates, D.; Kaye, S. M.; LaMarche, P. H.; LeBlanc, B.P.; Ménard, J.; Mueller, D.; Na, H.K.; Nishino, Norikazu; Paoletti, F.; Paul, S. F.; Sabbagh, S.A.; Soukhanovskii, V.; Stutman, D.

doi:10.1088/0029-5515/42/3/313

Cited by 40 publications

(19 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…11,19,[43][44][45][46][47][48] The degree of reduction varies, however, strongly from machine to machine, from 2 to 9 for carbon and from 3 to 15 for oxygen, depending on particular conditions, e.g., the gas composition used for boronization, the quality of covering produced, etc. Henceforth, we assume in our calculation that the erosion yields Y C and Y O are reduced after boronization by an averaged factor of 5, however, the results do not noticeably change if the reduction factor is 4 or larger.…”

Section: Edge Radiative Instability In the Noncoronal Approximationmentioning

confidence: 99%

The role of plasma–wall interactions in thermal instabilities at the tokamak edge

Tokar

Kelly

2003

Physics of Plasmas

View full text Add to dashboard Cite

Plasma-wall interaction leads to the release of impurities and neutrals of the working gas, which contribute significantly to the energy losses from the plasma edge, and therefore, crucially affects the development of thermal instabilities in fusion devices. An analytical model for impurity radiation is proposed, which takes into account the erosion mechanisms of wall material and the motion of impurity particles across magnetic surfaces. The temperature dependence of radiation losses is found to be very different from that predicted by the coronal approximation often used in considering thermal instabilities. The consequences for the development of poloidally symmetric detachment and multi-faceted asymmetric radiation from the edge ͑MARFE͒ are analyzed. It is demonstrated that the MARFE threshold principally depends on the mechanism by which working gas neutrals are released from the wall and on the neutral's properties, e.g., their ionization rate.

show abstract

Section: Edge Radiative Instability In the Noncoronal Approximationmentioning

confidence: 99%

The role of plasma–wall interactions in thermal instabilities at the tokamak edge

Tokar

Kelly

2003

Physics of Plasmas

View full text Add to dashboard Cite

show abstract

“…During this time room temperature air was blown through the QMB cooling lines to limit the temperature rise. During the campaign the vessel was periodically boronized using a glow discharge of trimethyl boron B(CD 3 ) 3 and helium [9].…”

Section: Introductionmentioning

confidence: 99%

Mass changes in NSTX surface layers with Li conditioning as measured by quartz microbalances

Skinner

Kugel

Roquemore

et al. 2009

Journal of Nuclear Materials

View full text Add to dashboard Cite

Abstract:Dynamic retention, lithium deposition, and the stability of thick deposited layers were measured by three quartz crystal microbalances (QMB) deployed in plasma shadowed areas at the upper and lower divertor and outboard midplane in the National Spherical Torus Experiment (NSTX).Deposition of 185 µg/cm 2 over 3 months in 2007 was measured by a QMB at the lower divertor while a QMB on the upper divertor, that was shadowed from the evaporator, received an order of magnitude less deposition. During helium glow discharge conditioning both neutral gas collisions and the ionization and subsequent drift of Li + interrupted the lithium deposition on the lower divertor. We present calculations of the relevant mean free paths. Occasionally strong variations in the QMB frequency were observed of thick lithium films suggesting relaxation of mechanical stress and/or flaking or peeling of the deposited layers.

show abstract

“…A recent machine upgrade permits baking at 350 º C, supplementing boronization [5] and helium glow to condition the first-wall surfaces, all of which were crucial to attaining high confinement reproducibility. H-mode access reproducibility is significantly enhanced with the use of center stack fueling [6].…”

Section: Introductionmentioning

confidence: 99%

Confinement studies of auxiliary heated NSTX plasmas

et al. 2004

Self Cite

View full text Add to dashboard Cite

Abstract:The confinement of auxiliary heated NSTX discharges is discussed. The energy confinement time in plasmas with either L-mode or H-mode edges is enhanced over the values given by the ITER97L and ITER98Pby(2) scalings, being up to 2-3 times L-mode and 1.5 times H-mode. TRANSP calculations based on the kinetic profile measurements reproduce the magnetics-based determination of stored energy and the measured neutron production rate. Power balance calculations reveal that, in a high power neutral beam heated H-mode discharge, the ion thermal transport is near neoclassical levels, and well below the electron thermal transport, which is the main loss channel. Perturbative impurity injection techniques indicate the particle diffusivity to be slightly above the neoclassical level in discharges with L-mode edge. High-harmonic fast-wave (HHFW) bulk electron heating is described and thermal transport is discussed. Thermal ion transport is found to be above neoclassical level, but thermal electron transport remains the main loss mechanism. Evidences of an electron thermal internal transport barrier obtained with HHFW heating are presented. A description of H-mode discharges obtained during HHFW heating is presented.

show abstract

Effect of boronization on ohmic plasmas in NSTX

Cited by 40 publications

References 27 publications

The role of plasma–wall interactions in thermal instabilities at the tokamak edge

The role of plasma–wall interactions in thermal instabilities at the tokamak edge

Mass changes in NSTX surface layers with Li conditioning as measured by quartz microbalances

Confinement studies of auxiliary heated NSTX plasmas

Contact Info

Product

Resources

About