Dynamic and static deuterium inventory in ASDEX Upgrade with tungsten first wall

Rohde, V.; Mayer, M.; Mertens, V.; Neu, R.; Sugiyama, K.

doi:10.1088/0029-5515/49/8/085031

Cited by 40 publications

(40 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The deuterium retention was investigated by post-mortem surface analysis [15] as well as in gas balance measurements [18]. Both analysis methods result in a strong reduction (≈ factor 10) compared to the results with C PFCs, in line with expectations from laboratory measurements on the deuterium retention in W. Detailed TDS, NRA and SIMS investigation reveal however, that the diffusion in bulk W is deeper than observed in similar samples from D irradiation in the laboratory [19].…”

supporting

confidence: 62%

Ten years of W programme in ASDEX Upgrade—challenges and conclusions

Neu¹,

Bobkov²,

Dux³

et al. 2009

Phys. Scr.

View full text Add to dashboard Cite

Abstract. Since 1999 ASDEX Upgrade increased its tungsten plasma facing components and finally reached a full W coverage in 2007. Most of the initial goals of the investigations were successfully achieved. A highlight of the investigations were multiple start-ups and operation without any boronisation demonstrating that performance and confinement similar to boronised operation with carbon PFCs can be reached in high power, high density discharges. This also allowed the investigation of the hydrogen retention without disturbing effects from the low-Z coating. A strong reduction of hydrogen retention was found in gas balance measurements as well as in post mortem analyses. On the other hand, an almost complete suppression of low-Z divertor radiation was achieved after boronisation, providing valuable information on the control requirements of radiative cooling by artificially introduced impurities. Among the challenges remains the strong increase of the W source and W concentration resulting from ICRH. At the same time it helped to identify the underlying physics and may lead to solutions superior to the presently used ones.

show abstract

supporting

confidence: 62%

Ten years of W programme in ASDEX Upgrade—challenges and conclusions

Neu¹,

Bobkov²,

Dux³

et al. 2009

Phys. Scr.

View full text Add to dashboard Cite

show abstract

“…This low value is compatible to in situ gas balance measurements. For a well analysed high density H-mode pulse [6], about 10 % of the gas input is remaining in the vessel directly when the plasma current ends. Subsequent outgassing in the following minutes leads to zero retention within the uncertainty of the gas balance measurement of £ 3 %.…”

Section: Campaign Integrated Deposited Layers and Fuel Retentionmentioning

confidence: 99%

Non-boronized compared with boronized operation of ASDEX Upgrade with full-tungsten plasma facing components

Kallenbach¹,

Dux²,

Mayer³

et al. 2009

Nucl. Fusion

Self Cite

112

114

View full text Add to dashboard Cite

Abstract. After completion of the tungsten coating of all plasma facing components, ASDEX Upgrade has been operated without boronization for 1 1/2 experimental campaigns. This has allowed the study of fuel retention under conditions of relatively low D co-deposition with low-Z impurities as well as the operational space of a full-tungsten device for the unfavourable condition of a relatively high intrinsic impurity level. Restrictions in operation were caused by central accumulation of tungsten in combination with density peaking, resulting in H-L backtransitions induced by too low separatrix power flux. Most important control parameters have been found to be the central heating power, as delivered predominantly by ECRH, and the ELM frequency, most easily controlled by gas puffing. Generally, ELMs exhibit a positive impact, with the effect of impurity flushing out of the pedestal region overbalancing the ELM induced W source. The restrictions of plasma operation in the unboronized W machine occured predominantly under low or medium power conditions. Under medium-high power conditions, stable operation with virtually no difference between boronized and unboronized discharges was achieved. Due to the reduced intrinsic radiation with boronization and the limited power handling capability of VPS coated divertor tiles ( 10 MW/m 2 ), boronized operation at high heating powers was possible only with radiative cooling. To enable this, a previously developed feedback system using (thermo-)electric current measurements as approximate sensor for the divertor power flux was introduced into the standard AUG operation. To avoid the problems with reduced ELM frequency due to core plasma radiation, nitrogen was selected as radiating species since its radiative characteristic peaks at lower electron temperatures in comparison to Ne and Ar, favouring SOL and divertor radiative losses. Nitrogen seeding resulted not only in the desired divertor power load reduction, but also in improved energy confinement, as well as in smaller ELMs.

show abstract

“…[38,39,40] • D-retention in refractory metals is low from laboratory experiments and observations in AUG with W films [41,42,43], as illustrated in Fig. 18; however, the high D retention observed in C-Mod with bulk Mo [44] has yet to be understood.…”

Section: Plasma Materials Interactionmentioning

confidence: 99%

High heat flux components—Readiness to proceed from near term fusion systems to power plants

Raffray¹,

Nygren²,

Whyte³

et al. 2010

Fusion Engineering and Design

Self Cite

125

View full text Add to dashboard Cite

A present topic of high interest in magnetic fusion is the "gap" between near-term and longterm concepts for high heat flux components (HHFC), and in particular their application in divertors. This paper focuses on this issue with the aim of characterizing the international status of current HHFC design concepts for ITER and describing the different technologies needed in the designs being developed for fusion power plants. Critical corresponding material and physics aspects are highlighted while evaluating the current readiness level of long-term concepts, identifying the design and R&D gaps, and discussing ways to bridge them.2

show abstract

Dynamic and static deuterium inventory in ASDEX Upgrade with tungsten first wall

Cited by 40 publications

References 24 publications

Ten years of W programme in ASDEX Upgrade—challenges and conclusions

Ten years of W programme in ASDEX Upgrade—challenges and conclusions

Non-boronized compared with boronized operation of ASDEX Upgrade with full-tungsten plasma facing components

High heat flux components—Readiness to proceed from near term fusion systems to power plants

Contact Info

Product

Resources

About