Interpretation of the observed radial electric field inversion in the TUMAN-3M tokamak during MHD activity

Rozhansky, V.; Тендлер, М.

doi:10.1088/0029-5515/48/7/075003

Cited by 30 publications

(49 citation statements)

References 13 publications

(43 reference statements)

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“…1). Note a significant positive perturbation in the potential during the MHD activity burst in the interval between t = 38 and 45 ms, which was considered in detail previously [8,9]. The MHD oscillation frequency during the MHD activity burst amounts to 5-12 kHz and is significantly differ ent from the GAM frequency (~28-32 kHz).…”

Section: Evolution Of Geodesic Acoustic Mode In Ohmic H Mode In Tumanmentioning

confidence: 63%

Evolution of geodesic acoustic mode in ohmic H-mode in TUMAN-3M tokamak

et al. 2012

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The concept of geodesic acoustic mode (GAM) was introduced in 1968 by Winsor et al. [1] in order to explain strong low frequency oscillations observed in the Model C stellarator. Since then, similar oscilla tions have been observed in many toroidal installa tions. In recent years, GAMs and other zonal flows (GAMs being a particular kind of these) attracted much attention and have been extensively studied both experimentally and theoretically [2,3] in respect of their influence on the plasma confinement. While not participating directly in the radial transport of energy and particles, GAMs can nevertheless influence the level of turbulence, the intensity of turbulent transport in plasma, and eventually the efficiency of plasma and energy confinement. Interrelation of the background turbulence, GAMs, and confinement regime was demonstrated by experiments on many toroidal devices and, in particular, in recent experiments on the AUG tokamak [4].This Letter presents the results of experiments on the TUMAN 3M tokamak [5] in a regime with the ohmic LH transition for the following parameters of plasma: minor radius, 22 cm; major radius, 52 cm; tor oidal magnetic field, 0.7 T; plasma current, 130 kA; safety factor, 2.5-3.3; average plasma density: from (0.8-0.9) × 10 19 m -3 in L mode to (3-4) × 10 19 m -3 in H mode. Figure 1 shows the temporal variation of some parameters in the H mode. Oscillations of the plasma potential at the GAM frequency were observed at the initial stage of discharge using the heavy ion beam probing (HIBP) techniques [6,7]. In these experi ments, the HIBP measurements were performed using 70 keV K + probing ions. The point of secondary ion ization of the injected ions was situated near the plasma column center and shifted relative to the initial position as a result of the temporal variation of the tor oidal magnetic field: r HIBP ~ 2.7 cm at t = 35 ms;Abstract-The behavior of a geodesic acoustic mode (GAM) in the TUMAN 3M tokamak has been exper imentally studied using the heavy ion beam probing technique. Oscillations of the electric potential under the action of a GAM localized at the plasma periphery have been detected. The GAM was observed in the regime of low confinement (L mode) with low plasma density (~0.8 × 10 19 m -3 ) and disappeared upon the transition to a high confinement regime (H mode). The possible role of GAM as a precursor of the improved confine ment (LH transition) is discussed.

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Section: Evolution Of Geodesic Acoustic Mode In Ohmic H Mode In Tumanmentioning

confidence: 63%

Evolution of geodesic acoustic mode in ohmic H-mode in TUMAN-3M tokamak

et al. 2012

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“…The electron conductivity is connected with the Rechester-Rosenbluth heat conductivity χ RR [81] by the Einstein relation σ St = 2i σ (e 2 n e /T e )χ RR . The radial electric field is determined by the ambipolarity condition j e = −j i and, therefore, the radial electric field in the presence of RMPs should be [82][83][84][85][86] …”

Section: Impact Of Resonant Magnetic Perturbations (Rmps)mentioning

confidence: 99%

Drifts, Currents, and Radial Electric Field in the Edge Plasma with Impact on Pedestal, Divertor Asymmetry and RMP Consequences

Rozhansky

2014

Contrib. Plasma Phys.

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Methanol is considered a promising liquid fuel in context with electrochemical energy conversion and storage for mobile applications. It is shown here that a direct methanol fuel cell can be used for spontaneous charging and discharging a supercapacitor (SC) for intermediate storage of chemical energy. Thereby, protons and electrons of the methanol‐derived hydrogen are stored separately in the electrical double layer of the SC electrode. The charging and discharging of this fuel cell–SC hybride device is investigated in experiments of spontaneous conditions (closed circuit) and also under externally enforced constant voltage sweep rate (cyclic voltammetry) and under constant current conditions. Alternatively, gas phase hydrogen is generated from methanol in an electro‐reforming process. When more efficient anode electrocatalysts become available this may become the method of choice for on‐board and on demand hydrogen production in mobile applications.

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“…In the presence of stochastization the jB force exerts a permanent toroidal torque on the plasma (see e.g. [9,10]). The resulting toroidal momentum is a measurable quantity (but requires measurements at different poloidal locations).…”

Section: Plasma Flows and In-out Asymmetries At The Core Edgementioning

confidence: 99%

The role of drifts in the plasma transport at the tokamak core–SOL interface

Chankin¹,

Coster²

2013

Journal of Nuclear Materials

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The interface between the core (inside the magnetic separatrix in X-point configurations) and the scrape-off layer (SOL) of tokamaks is a delicate region of the magnetic topology transition from closed to open field lines where neither the standard neoclassical theory nor the SOL physics fully apply. Sharp gradients of plasma parameters in the outer core, caused by the proximity of divertor sinks in the near SOL, invalidate some ordering assumptions of the neoclassical theory. At the same time, the existence of closed flux surfaces in the core enforces ambipolarity of radial plasma flows, in difference to the situation in the SOL where the current loop may close through the divertor. Detailed analysis of the plasma transport and flows with the emphasis on the outer core region, just inside the separatrix, is carried out in the paper, based on EDGE2D modelling and analytical formulas.

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Interpretation of the observed radial electric field inversion in the TUMAN-3M tokamak during MHD activity

Cited by 30 publications

References 13 publications

Evolution of geodesic acoustic mode in ohmic H-mode in TUMAN-3M tokamak

Evolution of geodesic acoustic mode in ohmic H-mode in TUMAN-3M tokamak

Drifts, Currents, and Radial Electric Field in the Edge Plasma with Impact on Pedestal, Divertor Asymmetry and RMP Consequences

The role of drifts in the plasma transport at the tokamak core–SOL interface

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