Fluctuation induced inward particle transport in the tokamak SOL plasma

Jha, Ratneshwar; Kaw, P. K.; Mattoo, S. K.; Rao, C. V. S.; Saxena, Y. C.; Singh, Raghvendra

doi:10.1088/0029-5515/33/8/i08

Cited by 20 publications

(14 citation statements)

References 12 publications

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“…Inward-directed, fluctuation-produced particle fluxes have been observed in several tokamak experiments [18,33], both inside and outside the separatrix. Ionization-driven drift wave instabilities have been considered as potential candidates to explain inward-directed particle fluxes [34].…”

Section: Discussionmentioning

confidence: 99%

Effect of the radial electric field on the fluctuation-produced transport in the H-1 heliac

Shats

1999

Plasma Phys. Control. Fusion

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Abstract. Highly coherent low-frequency fluctuations are studied experimentally in the low electron temperature plasma in the H-1 toroidal heliac. The fluctuations, presumably pressuregradient-driven resistive MHD modes, produce considerable radial particle transport. A build-up of strong sheared radial electric field leads to dramatic modifications in the fluctuation-driven transport. These modifications correlate with sudden changes in the plasma confinement, resembling low-tohigh transitions in other machines. Strong negative shear in the radial electric field eventually leads to the suppression of the fluctuations, while the onset of the strong positive shear correlates with the reversal of the fluctuation-driven particle flux, leading to the inward-directed pinch. It is concluded that the radial electric field modifies radial profiles of the fluctuation propagation velocity due to the Doppler shift, and it is this velocity shear which is important for the transport modifications.

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Section: Discussionmentioning

confidence: 99%

Effect of the radial electric field on the fluctuation-produced transport in the H-1 heliac

Shats

1999

Plasma Phys. Control. Fusion

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“…6 Furthermore, it should be noted that in the framework of the influence of probe's pre-sheath zone on local transport, fluctuation flux must be always in the same direction (there is no way for flow reversal), but this prediction seems to be in contradiction with previous experimental observations which have shown local flow reversal. [8][9][10] Measurements in stellarator devices have shown that the absolute value of the measured local E ϫ B transport is similar in both cases with inward and outward transport. 8,10 These changes seem to be related to magnetic topology and the structure of radial electric fields.…”

Section: Resultsmentioning

confidence: 89%

“…In some cases flow reversal can be inwards for some low frequencies and outwards at higher frequencies. 9 There are few experimental results of E ϫ B transport well inside the location of the velocity shear layer. In this respect, it is worth noting that experiments carried out in the Reversed Field Experiment device have shown a clear maximum in the fluctuation flux near the velocity shear layer location and then a decrease towards the inner plasma.…”

Section: Resultsmentioning

confidence: 99%

On the interpretation of fluctuation and E×B turbulent transport measured by Langmuir probes in fusion plasmas

Calderón¹,

Hidalgo²,

Pedrosa³

et al. 2004

Review of Scientific Instruments

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Plasma fluctuations and fluctuation-induced particle fluxes have been investigated in the plasma edge of the TJ-II stellarator using Langmuir probes. Simultaneous measurements of plasma fluctuations carried out by probes located in and out of the probe body sheath show similar results in the normalized level of fluctuations in the ion saturation current. However, floating potential fluctuations measured in the co and counter direction of the magnetic field on the sheath probe body show slight but significant differences. The local radial electrostatic turbulent driven transport measured in and out of the probe body sheath shows consistent results, within the errors bars due to uncertainties in the determination of the effective probe collecting area; the normalized local radial transport to the average ion saturation current (the effective velocity which is not affected by uncertainties in the probe area) show consistent results. These results and previous findings call into question the recent interpretation of probe measurements on the basis of the influence of the probe's pre-sheath zone [B. Labombard, Phys. Plasmas. 9, 1300 (2002)].

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“…Such models are expected to be important for future advanced tokamak control design. The effects of unsymmetrical toroidal magnetic fields and toroidal structure of tokamaks play important role in plasma shape [4,5]. The present work describes a non-rigid plasma base on analyzing of Mirnov oscillations in a MHD behavior.…”

Section: Introductionmentioning

confidence: 99%

MHD Instabilities and Toroidal Field Effects on Plasma Column Behavior in Tokamak

Khorshid

Wang

Ghoranneviss

et al. 2006

AIP Conference Proceedings

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Fluctuation induced inward particle transport in the tokamak SOL plasma

Cited by 20 publications

References 12 publications

Effect of the radial electric field on the fluctuation-produced transport in the H-1 heliac

Effect of the radial electric field on the fluctuation-produced transport in the H-1 heliac

On the interpretation of fluctuation and E×B turbulent transport measured by Langmuir probes in fusion plasmas

MHD Instabilities and Toroidal Field Effects on Plasma Column Behavior in Tokamak

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