Boronization with trimethylboron in the reversed field pinch RFX

Sonato, P.; Antoni, V.; Baker, William R.; Bertoncello, Renzo; Buffa, A.; Carraro, L.; Costa, S.; Mea, G. Della; Marrelli, L.; Murari, A.; Puiatti, M. E.; Rigato, V.; Scarin, P.; Tramontin, L.; Valisa, M.; Zandolin, S.

doi:10.1016/0022-3115(95)00161-1

Cited by 16 publications

(14 citation statements)

References 22 publications

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“…No significant erosion of the boronized layer was observed due to the exposure of the main discharges. The atomic ratio of boron to carbon, B/C, was approximately 1/3, which was similar to that of the boron film prepared by helium discharge using trimethylboron in RFX [10]. After the boronization followed by the exposure to the deuterium main discharges and the helium glow discharges ( fig.2(d)), the thickness of boronized layer after the exposure of the helium glow discharges was approximately 30 nm, which was slightly thinner than that before the exposure.…”

Section: 1supporting

confidence: 65%

Deuterium retention of low activation ferritic steel and boronized wall in JFT-2M

Yamauchi

Yamaguchi

Hirohata

et al. 2006

Fusion Engineering and Design

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JAPAN AbstractDeuterium retention and erosion of F82H exposed to JFT-2M plasmas and the effect of boronization on the deuterium retention were examined based on material probe analysis. The amount of retained deuterium almost saturated after 300 main discharges of deuterium. The retention of helium was clearly observed after helium glow discharge. The desorption temperature was approximately 600 K. While no significant change in the surface atomic composition was observed after the exposure of main discharges, the mixture layer of carbon, iron and oxygen was observed after the helium glow discharge due to surface erosion and redeposition of eroded particles.After the boronization using trimethylboron, both carbon and boron deposited at the surface. The atomic ratio of B to C was 1/3. The amount of retained deuterium significantly increased, three times larger than that before the boronization, owing to that a large amount of deuterium is trapped in the carbon content.

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Section: 1supporting

confidence: 65%

Deuterium retention of low activation ferritic steel and boronized wall in JFT-2M

Yamauchi

Yamaguchi

Hirohata

et al. 2006

Fusion Engineering and Design

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“…The dependence of the total emitted radiation on plasma purity has been confirmed by comparing the γ ratio for reproducible low current discharges (from 0.5 to 0.7 MA) at various densities before and after the deposition of a thin film containing boron [21] on the graphite first wall. The boronization was performed with a radiofrequency assisted glow discharge cleaning (GDC) in a throughflow of a mixture of helium and trimethylboron.…”

Section: Inversion Algorithm and Experimental Resultsmentioning

confidence: 89%

Total radiation losses and emissivity profiles in RFX

Marrelli¹,

Martin

Murari

et al. 1998

Nucl. Fusion

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Abstract.The radiation emitted by RFX plasmas has been investigated using a 8 chord-bolometric camera, whose detectors have been calibrated absolutely. From the experimental data the emissivity profiles have been reconstructed by means of a generalized tomography reconstruction algorithm. This analysis confirms that the emitted radiation in RFX is systematically concentrated at the edge. The emitted power dependence on the plasma density shows that the radiation increases approaching the high density regime, but it rarely goes beyond 30% of the input power for stationary discharges. This behaviour is strongly dependent on the concentration of impurities, but in any case in RFX there is no evidence of disruptions. A simple local energy balance allows to obtain a preliminary evaluation of the radial heat flux profile.

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“…To overcome the described limitation inner shot wall conditioning treatments and hot wall operation have been tested. Sessions of He discharges, helium glow discharge cleanings (HeGDCs), wall boronization [13] and wall baking are routinely used, but none of them provided a solution stationary over many discharges. Boronization coating is the most effective in controlling hydrogen influx over about 100 discharges [14] (the exact number depends on discharge characteristics: plasma current, duration, density value) but it is ineffective in modifying the density profiles or improving the plasma performance significantly.…”

Section: Introductionmentioning

confidence: 99%

RFX-mod wall conditioning by lithium pellet injection

et al. 2012

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Plasma–wall interaction is one of the most important issues that present magnetic confinement devices have to face. In the RFX-mod reversed field pinch experiment plasma–wall interaction has become a hard point increasing plasma current up to the RFX-mod maximum design value of 2 MA, since in this case local power deposition can be as high as 10 MW m−2. Since the first wall of RFX-mod is entirely covered by graphite tiles different techniques have been tested to control hydrogen wall influx: He glow discharges cleaning, He discharges at high plasma currents, wall boronization and baking. With the best results obtained by boronization, at high plasma currents all such techniques improve the situation but do not allow a complete and stationary hydrogen influx reduction. Furthermore, in the presence of localized high power load the wall still responds providing very high influxes. In order to improve this situation wall conditioning by lithium has been tested. As a first lithization method to deposit a controllable amount of lithium on the wall, a room temperature pellet injector has been used (maximum pellet diameter of 1.8 mm and maximum length of 5 mm). Lithium coatings with a theoretical thickness of about 10 nm have been applied both to clean graphite tiles and over boronized ones. Lithization demonstrated to be effective in lowering hydrogen wall recycling to a value smaller than that of boronized graphite, with the effect lasting 20–30% more than in the boronized case. Compared with boronization, lithization slightly improves (by about 30%) particle confinement time and also clearly affects edge particle transport providing a lower edge density and more peaked density profiles. Lithization also reduces carbon content by about 10% over boronization but still no clear improvement has been observed in terms of energy confinement. Similar results have been obtained performing lithization over boronized graphite.

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Boronization with trimethylboron in the reversed field pinch RFX

Cited by 16 publications

References 22 publications

Deuterium retention of low activation ferritic steel and boronized wall in JFT-2M

Deuterium retention of low activation ferritic steel and boronized wall in JFT-2M

Total radiation losses and emissivity profiles in RFX

RFX-mod wall conditioning by lithium pellet injection

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