Impurity production and plasma performance in ASDEX discharges with ohmic and auxiliary heating

Fußmann, G.; Team, Asdex; Team, NI; Team, Icrh; Hofmann, J.; Janeschitz, G.; Lenoci, M.; Mast, F.; McCormick, K.; Mürmann, H.; Poschenrieder, W.; Roth, J.; Setzensack, C.; Staudenmaier, G.; Steuer, K.-H.; Taglauer, E.; Verbeek, H.; Wagner, F.; Becker, G.; Bosch, H.‐S.; Brocken, H.; Eberhagen, A.; Gehre, O.; Gernhardt, J.; Gierke, G. von; Clock, E.; Gruber, O.; Haas, G.; Izvozchikov, A.; Karger, F.; Kaufmann, Michael; Keilhacker, M.; Klüber, O.; Kornherr, M.; Lackner, K.; Lisitano, G.; Mayer, H. M.; Meisel, D.; Mertens, V.; Müller, E.; Neuhäuser, J.; Niedermeyer, H.; Noterdaeme, Jean-Marie; Pietrzyk, Z.A.; Rapp, H.; Riedler, H.; Röhr, H.; Ryter, F.; Schneider, F.; Siller, G.; Smeulders, P.; Söldner, F. X.; Speth, E.; Steinmetz, K.; Tsois, N.; Ugniewski, S.; Vollmer, O.; Wesner, F.; Zasche, D.

doi:10.1016/0022-3115(87)90314-x

Cited by 36 publications

(2 citation statements)

References 7 publications

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“…High performance and steady state operation is a crucial goal of current magnetic fusion research. However, it is always observed the impurity accumulates inevitably in H-mode discharges, which affects the performance of confinement and even leads to disruptions [39][40][41]. For EAST, efforts have been made to achieve the steady state H-mode discharge.…”

Section: The Confinement Characteristic Of High-enhanced-recycling (H...mentioning

confidence: 99%

Investigation of impurity confinement in lower hybrid wave heated plasma on EAST tokamak

Zhang

et al. 2017

Nucl. Fusion

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The transient perturbation method with metallic impurities such as iron (Fe, Z = 26) and copper (Cu, Z = 29) induced in plasma-material interaction (PMI) procedure is used to investigate the impurity confinement characters in lower hybrid wave (LHW) heated EAST sawtooth-free plasma. The dependence of metallic impurities confinement time on plasma parameters (e.g. plasma current, toroidal magnetic field, electron density and heating power) are investigated in ohmic and LHW heated plasma. It is shown that LHW heating plays an important role in the reduction of the impurity confinement time in L-mode discharges on EAST. The impurity confinement time scaling is given as 42I 0.32 P B 0.2 t n 0.43 e P −0.4 total on EAST, which is close to the observed scaling on Tore Supra and JET. Furthermore, the LHW heated high-enhanced-recycling (HER) H-mode discharges with ~25 kHz edge coherent modes (ECM), which have lower impurity confinement time and higher energy confinement time, provide promising candidates for high performance and steady state operation on EAST.

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Section: The Confinement Characteristic Of High-enhanced-recycling (H...mentioning

confidence: 99%

Investigation of impurity confinement in lower hybrid wave heated plasma on EAST tokamak

Zhang

et al. 2017

Nucl. Fusion

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“…The two essential impurity production processes occurring at the first wall are physical and chemical sputtering [1][2][3]. Many experiments on impurity behaviours and transport have been performed in tokamaks, and a well-known database for these various processes is described in [4][5][6][7][8][9]. The impurity content of the plasma for a given geometry and given operating conditions, the flux and energy distributions of the plasma arriving at the wall, and also the transport of the impurities from the source are investigated in JET [10].…”

Section: Introductionmentioning

confidence: 99%

Impurity and density behaviours during long pulse discharges in HT-7

Huang¹,

Wan²,

Gong³

et al. 2006

Plasma Phys. Control. Fusion

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Intrinsic plasma impurity behaviours are surveyed by passive spectroscopy in different operation conditions, but with emphasis on long pulse discharges in the HT-7 tokamak. Some complicated behaviours and time evolution are shown for carbon and oxygen impurities resulting from plasma-wall interactions. Uncontrollable increase in density is observed, correlated with impurity concentrations, injected energy and local heat flux on limiter. Under certain conditions, high impurity radiation and uncontrollable density can reduce LHCD efficiency and thus lead to discharge terminations. A major aim of RF wall conditioning is to reduce impurity levels in the plasma. Furthermore, a new operation mode has been successfully developed, by means of LHCD power feedback control, to obtain full non-inductive current driven and long duration plasma. As a result, the longest pulse discharge with a T e (0) ∼ 1.0 keV, n e (0) ∼ 0.75 × 10 19 m 3 has been achieved with a duration of over 306 s.

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The Relative Importance of Wall and Target Impurity Sources in Divertor Tokamaks

Stangeby

Elder

1992

Contrib. Plasma Phys.

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Experiments in JET operated with X-point discharges have shown that wallproduced impurity influxes can be significantly more effective at contaminating the core plasma than plate-produced influxes. The DlVlMP (Wertor b u r i t y ) Monte Carlo impurity productionfiransport code is used to study core contamination efficiency assuming a wide variety of models/assurnptions for the plasma edge behaviour, including forced fuel recirculation (pumped divertor mode) and spontaneous flow reversal. It is found that for an open (X-point) divertor geometry and for plasma conditions typical of low Tie operation that a wall source is -3-5x more effective at contaminating the core than a target source of equal strength. For high iie conditions the wall source is >lox more effective than the target source.

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Impurity production and plasma performance in ASDEX discharges with ohmic and auxiliary heating

Cited by 36 publications

References 7 publications

Investigation of impurity confinement in lower hybrid wave heated plasma on EAST tokamak

Investigation of impurity confinement in lower hybrid wave heated plasma on EAST tokamak

Impurity and density behaviours during long pulse discharges in HT-7

The Relative Importance of Wall and Target Impurity Sources in Divertor Tokamaks

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