Fluctuations in the scrape-off layer and edge plasma of the COMPASS tokamak

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61389021%3A_____%2F18%3A00501889" target="_blank" >RIV/61389021:_____/18:00501889 - isvavai.cz</a>

Result on the web

<a href="http://ocs.ciemat.es/EPS2018PAP/pdf/P1.1103.pdf" target="_blank" >http://ocs.ciemat.es/EPS2018PAP/pdf/P1.1103.pdf</a>

DOI - Digital Object Identifier

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Result language

angličtina

Original language name

Fluctuations in the scrape-off layer and edge plasma of the COMPASS tokamak

Original language description

We have identified two distinct types of turbulent fluctuations in COMPASS plasmas, the high-frequency edge oscillations and low-frequency SOL blobs. The transition region is localized in the near SOL, where both types spatially overlap and interact and the radial particle transport gradually transfers from high to low frequencies. Even though skewness of isat fluctuations is positive even inside LCFS, distinguishable Gamma-distributed PDF, formed by the low-frequency fluctuations, arises in the near SOL. This supports, together with turbulence spreading rate being positive in the near SOL but negative in the edge, the picture presented in [3] that most of the fluctuations that form a positive skewness in the edge region disappear around LCFS and new blobs are formed in the near SOL. Further, we cannot confirm the assumption that the blobs are generated randomly according to a Poisson process. Oscillations of all measured quantities, incl. radial particle flux, in the near SOL are peaked around ∼13 kHz. This seems to correspond to a poloidally rotating structure with a rather large poloidal wave-length ∼ 15 − 20 cm, that at least partly modulates blob generation. Nevertheless, we note that time separation of blobs becomes more random further in the SOL, possibly due to differences in their individual propagation. These observations hold for diverted plasmas, but the situation may be different in limited low-elongation plasmas where the radius of zero skewness was observed to be shifted significantly (several cm) inwards, compared to diverted configuration, and Gamma-like PDF is detected even inside the LCFS. Study of these plasmas is ongoing.

Czech name

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Czech description

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Type

D - Article in proceedings

CEP classification

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OECD FORD branch

10305 - Fluids and plasma physics (including surface physics)

Project

Result was created during the realization of more than one project. More information in the Projects tab.

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2018

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Article name in the collection

45th EPS Conference on Plasma Physics

ISBN

9781510868441

ISSN

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e-ISSN

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Number of pages

4

Pages from-to

481-484

Publisher name

45th EPS Conference on Plasma Physics

Place of publication

Mulhouse

Event location

Praha

Event date

Jul 2, 2018

Type of event by nationality

WRD - Celosvětová akce

UT code for WoS article

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