Radial current in a tokamak caused by a biased electrode

Askinazi, L. G.; Golant, V.E.; Лебедев, С. В.; Rozhanskij, V.A.; Тендлер, М.

doi:10.1088/0029-5515/32/2/i07

Cited by 96 publications

(55 citation statements)

References 8 publications

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“…This result is not a surprise: many tokamak experiments have documented that the damping of flows in the symmetry direction ͑the toroidal direction in that case͒ is faster than neoclassical theory predicts. 45,[47][48][49][50][51][52] In this sense, the damping of flows in the quasisymmetric HSX is similar to that in axisymmetric tokamaks.…”

Section: Discussion Of Enhanced Flow Damping In Hsxmentioning

confidence: 99%

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Measurements and modeling of plasma flow damping in the Helically Symmetric eXperiment

et al. 2005

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Fusion Technology 27, 273 ͑1995͔͒ using a biased electrode to impulsively spin the plasma and Mach probes to measure the rotation. There is a distinct asymmetry between the spin-up when the bias is initiated and relaxation when the electrode current is broken. In each case, two time-scales are observed in the evolution of the plasma flow. These observations motivate the development of new neoclassical modeling techniques, including a new model where the fast increment of the electric field initiates the spin-up process. The flow in the quasisymmetric configuration rises more slowly and to a higher value than in a configuration with the quasisymmetry broken, and the rise time-scale is in reasonable agreement with the neoclassical spin-up model. The flows decay more slowly in the quasisymmetry configuration than in the configuration with the quasisymmetry broken, although the decay rates are significantly faster than the neoclassical prediction.

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Section: Discussion Of Enhanced Flow Damping In Hsxmentioning

confidence: 99%

“…45 Rozhansky and Tendler 46 have constructed a model that approximately predicts the radial conductivity in the L mode in TUMAN-3. This model assumes that there exists anomalous shear viscosity to damp the toroidal flow.…”

Section: ٌ͉͉͗͘mentioning

confidence: 99%

Measurements and modeling of plasma flow damping in the Helically Symmetric eXperiment

et al. 2005

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“…On several tokamaks (CCT [204,205], TUMAN-3 [206], TEXTOR [207] and others) biasing experiments were performed, where a biased electrode was inserted into the core plasma. Thus the potential of the order of few hundred eV was applied to the core flux surface with respect to the limiter, and the current-voltage characteristic was measured.…”

Section: Simulation Of Biasing Experimentsmentioning

confidence: 99%

Plasma Edge Physics with B2‐Eirene

Schneider

Bonnin

Borraß

et al. 2006

Contrib. Plasma Phys.

477

426

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The B2‐Eirene code package was developed to give better insight into the physics in the scrape‐off layer (SOL), which is defined as the region of open field‐lines intersecting walls. The SOL is characterised by the competition of parallel and perpendicular transport defining by this a 2D system. The description of the plasma‐wall interaction due to the existence of walls and atomic processes are necessary ingredients for an understanding of the scrape‐off layer. This paper concentrates on understanding the basic physics by combining the results of the code with experiments and analytical models or estimates. This work will mainly focus on divertor tokamaks, but most of the arguments and principles can be easily adapted also to other concepts like island divertors in stellarators or limiter devices. The paper presents the basic equations for the plasma transport and the basic models for the neutral transport. This defines the basic ingredients for the SOLPS (Scrape‐Off Layer Plasma Simulator) code package. A first level of understanding is approached for pure hydrogenic plasmas based both on simple models and simulations with B2‐Eirene neglecting drifts and currents. The influence of neutral transport on the different operation regimes is here the main topic. This will finish with time‐dependent phenomena for the pure plasma, so‐called Edge Localised Modes (ELMs). Then, the influence of impurities on the SOL plasma is discussed. For the understanding of impurity physics in the SOL one needs a rather complex combination of different aspects. The impurity production process has to be understood, then the effects of impurities in terms of radiation losses have to be included and finally impurity transport is necessary. This will be introduced with rising complexity starting with simple estimates, analysing then the detailed parallel force balance and the flow pattern of impurities. Using this, impurity compression and radiation instabilities will be studied. This part ends, combining all the elements introduced before, with specific, detailed results from different machines. Then, the effect of drifts and currents is introduced and their consequences presented. Finally, some work on deriving scaling laws for the anomalous turbulent transport based on automatic edge transport code fitting procedures will be described. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…Biased electrode experiments in tokamaks, [5]- [7] have shown that there is a sudden jump in the radial electric field during the L-H transition about a poloidal Mach number where is the speed of light, is the radial electric field, is poloidal magnetic field, and is the thermal velocity of ions) of unity. These experiments indicated that the viscosity in tokamaks is nonlinear.…”

Section: Introductionmentioning

confidence: 99%

Effects of plasma parameters on viscosity

Dahi

Talmadge²,

Shohet³

1998

IEEE Trans. Plasma Sci.

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Abstract-A numerical code is developed to study the effect of ion density and temperature (as well as ion pressure and temperature gradients) on the amplitude of the local maxima of the poloidal viscosity with respect to the poloidal Mach number using the model developed by Shaing [1]. The sum of the poloidal viscosity and ion-neutral collisions is determined from the dependence of the plasma radial current on the radial electric field in a biased electrode experiment. The experimental results in the interchangeable module stellarator agree qualitatively with the predictions of the numerical calculation regarding the effects of variation of ion density and temperature on viscosity.

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Radial current in a tokamak caused by a biased electrode

Cited by 96 publications

References 8 publications

Measurements and modeling of plasma flow damping in the Helically Symmetric eXperiment

Measurements and modeling of plasma flow damping in the Helically Symmetric eXperiment

Plasma Edge Physics with B2‐Eirene

Effects of plasma parameters on viscosity

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