Effect of lithium wall conditioning on deuterium in-vessel retention in the TdeV tokamak

Terreault, B.; Guo, Heng; Kéroack, D.; Paynter, R.W.; Zuzak, W.; Abel, G.; Ennaceur, M.M; Gauvreau, J. L.; Haddad, E.; Leblanc, L.; Ross, G.G.; Mai, H.; Richard, Nicolas; Stansfield, B.L.; Team, TdeV; Caorlin, M.; Owens, D. K.; Mueller, D.; Pitcher, S.; Marche, P.H. La; Strachan, J.D.; Arps, James H.; Weller, Robert A.

doi:10.1016/0022-3115(94)00488-9

Cited by 18 publications

(4 citation statements)

References 7 publications

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“…In particular, no plasma disruptions were recorded. This result is in agreement with that from the TdeV tokamak experiment where a rather small amount of lithium was used [7]. Moreover, it is worth mentioning that the physics behind the droplets formation is not yet understood.…”

Section: E6idence Of a Large Number Of Small Lithium Dropletssupporting

confidence: 89%

“…Using lithium pellet in combination with high power neutral beam injection enabled the TFTR tokamak to achieve high plasma performance [6]. Evaporating lithium to getter the inside walls of a tokamak was also done in the TdeV [7] and JIPP T-IIU tokamaks [8]. However, unlike in TFTR, no significant confinement enhancement was reported in these devices, although the role of lithium to reduce impurities in the plasma was confirmed.…”

Section: Introductionmentioning

confidence: 99%

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Plasma–lithium interaction in the CDX-U spherical torus

Antar

Doerner

Kaita

et al. 2002

Fusion Engineering and Design

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Results on the interaction between plasma in the current drive experiment-upgrade (CDX-U) spherical torus and a liquid lithium limiter are reported. It is observed that macroscopic lithium droplets detach from the limiter head and fall towards the plasma core. However, no disruptions occurred during these discharges despite the fact that relatively large-scale blobs are observed entering the confined plasma. A multi-tip Langmuir probe measures the edge plasma properties. It is found that the average density and temperature and their fluctuations are unaffected by the presence of lithium within experimental error.

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Section: E6idence Of a Large Number Of Small Lithium Dropletssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Plasma–lithium interaction in the CDX-U spherical torus

Antar

Doerner

Kaita

et al. 2002

Fusion Engineering and Design

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“…The fluid character, as well as the magnetohydrodynamics (MHD) features of molten salts and liquid metals, especially liquid lithium, has been intensively investigated by the APEX team using simulation and laboratory experiments [7]. Also, related experiments were conducted in some tokamak devices, such as TFTR [8][9][10][11][12][13], TdV [12], CDX-U [14], FTU [15] and DIII-D [16]. The lithium divertor/wall showed a number of advantages for removing incident tritium and impurity effluxes, providing a self-healing plasma facing surface in a diverted high power DT reactor [7,17,18], and enabling a lithium wall fusion regime [19].…”

Section: Introductionmentioning

confidence: 99%

Characteristics of energy transport of Li-conditioned and non-Li-conditioned plasmas in the National Spherical Torus Experiment (NSTX)

Ding

Kaye

Bell

et al. 2009

Plasma Phys. Control. Fusion

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The transport properties of NSTX plasmas obtained during the 2008 experimental campaign have been studied and are reported here. Transport trends and dependences have been isolated, and it is found that both electron and ion energy transport coefficients have strong dependences on local values of n∇T , which in turn is strongly dependent on local current density profile. Without identifying this dependence, it is difficult to identify others, such as the dependence of transport coefficients on B p (or q), I p and P heat . In addition, a comparison between discharges with and without Lithium wall conditioning has been made. While the trends in the two sets of data are similar, the thermal transport loss, especially in the electron channel, is found to strongly depend on the amount of Lithium deposited, decreasing by up to 50% of its no-Lithium value.

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“…For the former, several techniques to control particle recycling have been developed in a number of magnetic fusion devices. For example, liquid lithium as a PFM (for plasma facing material) or lithium coatings to cover PFCs have been tested as one of the candidates of surface coating methods in TdeV [11], FTU [12], CDX-U [13] and NSTX [14]. It is understood that lithium absorbs hydrogen until it is fully saturated to form LiH, during which period reduced recycling, i.e.…”

Section: Introductionmentioning

confidence: 99%

Active particle control experiments and critical particle flux discriminating between the wall pumping and fuelling in the compact plasma wall interaction device CPD spherical tokamak

et al. 2009

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Two approaches associated with wall recycling have been performed in a small spherical tokamak device CPD (compact plasma wall interaction experimental device), that is, (1) demonstration of active particle recycling control, namely, ‘active wall pumping’ using a rotating poloidal limiter whose surface is continuously gettered by lithium and (2) a basic study of the key parameters which discriminates between ‘wall pumping and fuelling’. For the former, active control of ‘wall pumping’ has been demonstrated during 50 kW RF current drive discharges whose pulse length is typically ∼300 ms. Although the rotating limiter is located at the outer board, as soon as the rotating drum is gettered with lithium, hydrogen recycling measured with Hα spectroscopy decreases by about a factor of 3 not only near the limiter but also in the centre stack region. Also, the oxygen impurity level measured with O II spectroscopy is reduced by about a factor of 3. As a consequence of the reduced recycling and impurity level, RF driven current has nearly doubled at the same vertical magnetic field. For the latter, global plasma wall interaction with plasma facing components in the vessel is studied in a simple torus produced by electron cyclotron waves with I p < 1 kA. A static gas balance (pressure measurement) without external pumping systems has been performed to investigate the role of particle flux on a transition of ‘wall fuelling’ to ‘wall pumping’. It is found that a critical particle flux exists to discriminate between them. Beyond the critical value, a large fraction (∼80%) of pressure drop (‘wall pumping’) is found, suggesting that almost all injected particles are retained in the wall. Below it, a significant pressure rise (‘wall fuelling’) is found, which indicates that particles are fuelled from the wall during/just after the discharge. Shot history effects (integrated particle recycling behaviour from the plasma facing surfaces) are seen on that the critical particle flux is reducing from 0.8 × 10−4 to ∼0.1 × 10−4 Torr during the experimental campaign (∼3000 shots). In the wall pumping pressure range the wall pumping fraction is reduced with increasing surface temperature up to 150 °C.

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Effect of lithium wall conditioning on deuterium in-vessel retention in the TdeV tokamak

Cited by 18 publications

References 7 publications

Plasma–lithium interaction in the CDX-U spherical torus

Plasma–lithium interaction in the CDX-U spherical torus

Characteristics of energy transport of Li-conditioned and non-Li-conditioned plasmas in the National Spherical Torus Experiment (NSTX)

Active particle control experiments and critical particle flux discriminating between the wall pumping and fuelling in the compact plasma wall interaction device CPD spherical tokamak

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