Observation of vortex-like coherent structures in the edge plasma of the ADITYA tokamak

Joseph, Biju K; Jha, Ratneshwar; Kaw, P. K.; Mattoo, S. K.; Rao, C. V. S.; Saxena, Y. C.; Team, Aditya

doi:10.1063/1.872611

Cited by 55 publications

(35 citation statements)

References 30 publications

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“…Additionally, characteristic power spectra of density and floating potential fluctuations are observed and spatio-temporally resolved measurements indicate the existence of large scale structures [9] - [13]. Although these findings support the existence of a dual cascade, an experimental verification is desired, which is a difficult task for hot and dense fusion plasmas.…”

Section: Introductionmentioning

confidence: 80%

Observation of Mode like Coherent Structures in Curved Magnetic Fields of a Simple Magnetized Torus

Greiner¹,

Block

Piel

2004

Contrib. Plasma Phys.

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The spatio-temporal dynamics of large-scale structures in curved magnetic field of simple magnetized torus (SMT) are presented. The experiments are performed in the SMT BLAAMANN and employ the techniques of conditional averaging (CA) and cross-correlation (CCF) of Langmuir probe data. By means of a detailed comparison of radio-frequency and thermionic discharges, it is shown that general features of the observed large-scale structures are independent of the discharge mechanism. Further, the observed large scale structures have a pronounced spatio-temporal periodicity, which suggests a description as mode-like. The conjectured relationship between the observed coherent structures and the inverse energy cascade is therefore questioned again.

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Section: Introductionmentioning

confidence: 80%

Observation of Mode like Coherent Structures in Curved Magnetic Fields of a Simple Magnetized Torus

Greiner¹,

Block

Piel

2004

Contrib. Plasma Phys.

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“…It should be noted that while non-Gaussian PDFs, intermittency, and motion of coherent structures has been well documented over a number of years [88,89,90,91,92,93,94,95,96,97], clear connections to a rapid cross-field transport mechanism in the far SOL and the potential impact on tokamak reactor operation have only recently been widely recognized.…”

Section: Particle Transport In the Solmentioning

confidence: 99%

Chapter 4: Power and particle control

Loarte¹,

et al. 2007

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Abstract.Progress, since the ITER Physics Basis publication, in understanding the processes that will determine the properties of the plasma edge and its interaction with material elements in ITER is described. Experimental areas where significant progress has taken place are : energy transport in the SOL in particular of the anomalous transport scaling, particle transport in the SOL that plays a major role in the interaction of diverted plasmas with the main chamber material elements, ELM energy deposition on material elements and the transport mechanism for the ELM energy from the main plasma to the plasma facing components, the physics of plasma detachment and neutral dynamics including the edge density profile structure and the control of plasma particle content and He removal, the erosion of low and high Z materials in fusion devices, their transport to the core plasma and their migration at the plasma edge including the formation of mixed materials, the processes determining the size and location of the retention of tritium in fusion devices and methods to remove it and the processes determining the efficiency of the various fuelling methods as well as their development towards the ITER requirements. This experimental progress has been accompanied by the development of modelling tools for the physical processes at the edge plasma and plasma-materials interaction and the further validation of these models by comparing their predictions with the new experimental results. Progress in the modelling development and validation has been mostly concentrated in the following areas : refinement of the predictions for ITER with plasma edge modelling codes by inclusion of detailed geometrical features of the divertor and the introduction of physical effects, which can play a 2 major role in determining the divertor parameters at the divertor for ITER conditions such as hydrogen radiation transport and neutral-neutral collisions, modelling of the ion orbits at the plasma edge, which can play a role in determining power deposition at the divertor target, models for plasma-materials and plasma dynamics interaction during ELMs and disruptions, models for the transport of impurities at the plasma edge to describe the core contamination by impurities and the migration of eroded materials at the edge plasma and its associated tritium retention and models for the turbulent processes that determine the anomalous transport of energy and particles across the SOL. The implications for the expected performance of the reference regimes in ITER, the operation of the ITER device and the lifetime of the plasma facing materials are discussed. Introduction.This chapter outlines the significant progress achieved since the ITER Physics Basis in understanding basic scrape-off layer (SOL) and divertor processes in a tokamak. The interaction of plasma with first-wall surfaces will have considerable impact on the performance of fusion plasmas, the lifetime of plasma facing components, and the retention of tritium in next step Burning Plasma E...

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“…A candidate for the additional edge/SOL transport, intermittency in the fluctuations corresponding to a significant number of events above the standard deviation, has been extensively documented in linear devices, 6,7 stellarators 8 and tokamaks [9][10][11] and its statistical properties examined 12 via the probability distribution function 13 ͑PDF͒. The essential result is that the fluctuations depart from a Gaussian distribution, featuring skewness 13 and kurtosis 13 that correspond to the presence of a significant number of events above the standard deviation.…”

Section: Introductionmentioning

confidence: 99%

Transport by intermittent convection in the boundary of the DIII-D tokamak

et al. 2001

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Intermittent plasma objects ͑IPOs͒ featuring higher pressure than the surrounding plasma, and responsible for ϳ50% of the EϫB T radial transport, are observed in the scrape off layer ͑SOL͒ and edge of the DIII-D tokamak ͓J. Watkins et al., Rev. Sci. Instrum. 63, 4728 ͑1992͔͒. Conditional averaging reveals that the IPOs, produced at a rate of ϳ3ϫ10 3 s Ϫ1 , are positively charged and also polarized, featuring poloidal electric fields of up to 4000 V/m. The IPOs move poloidally at speeds of up to 5000 m/s and radially with EϫB T /B 2 velocities of ϳ2600 m/s near the last closed flux surface ͑LCFS͒, and ϳ330 m/s near the wall. The IPOs slow down as they shrink in radial size from 4 cm at the LCFS to 0.5 cm near the wall. The IPOs appear in the SOL of both L and H mode discharges and are responsible for nearly 50% of the SOL radial EϫB transport at all radii; however, they are highly reduced in absolute amplitude in H-mode conditions.

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Observation of vortex-like coherent structures in the edge plasma of the ADITYA tokamak

Cited by 55 publications

References 30 publications

Observation of Mode like Coherent Structures in Curved Magnetic Fields of a Simple Magnetized Torus

Observation of Mode like Coherent Structures in Curved Magnetic Fields of a Simple Magnetized Torus

Chapter 4: Power and particle control

Transport by intermittent convection in the boundary of the DIII-D tokamak

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