ELM temperature in JET and COMPASS tokamak divertors

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A21340%2F23%3A00381527" target="_blank" >RIV/68407700:21340/23:00381527 - isvavai.cz</a>

Alternative codes found

RIV/61389021:_____/23:00572762

Result on the web

<a href="https://doi.org/10.1088/1741-4326/acbf68" target="_blank" >https://doi.org/10.1088/1741-4326/acbf68</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1088/1741-4326/acbf68" target="_blank" >10.1088/1741-4326/acbf68</a>

Result language

angličtina

Original language name

ELM temperature in JET and COMPASS tokamak divertors

Original language description

Analysis of the divertor edge localized mode (ELM) electron temperature at a uniquely high temporal resolution (10(-5) s) was reported at the JET tokamak (Guillemaut et al 2018 Nucl. Fusion 58 066006). By collecting divertor probe data obtained during many dozens of ELMs, the conditional-average (CAV) technique yields surprisingly low peak electron temperatures, far below the pedestal ones (70%-99% reduction!) which we, however, question. This result was interpreted through the collisional free-streaming kinetic model of ELMs, by a transfer of most of the electron energy to ions, implying a high tungsten sputtering for unmitigated ELMs in future fusion devices like ITER. Recently, direct microsecond temperature measurements on the COMPASS tokamak, however, showed that the electron temperature peak of ELM filaments measured in the divertor is reduced by less than a third with respect to the pedestal one. This was further confirmed by a dedicated 1D particle-in-cell (PIC) simulation and tends to prove that the pedestal electrons can transfer only their parallel energy to ions (due to low collisionality), thus less than a third, as is predicted by the collisionless free-streaming model. This finding strongly contradicts the JET observations. We have therefore compared the CAV to the direct (microsecond) ball-pen and Langmuir probes measurements in COMPASS and found very good agreement between them. Revisiting the aforementioned JET CAV analysis indeed shows that the electron temperatures are much higher than previously reported, close to those predicted by the PIC simulation, and thus the ion energy seems to not significantly increase in the scrape-off layer.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10305 - Fluids and plasma physics (including surface physics)

Project

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Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2023

Confidentiality

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

Name of the periodical

Nuclear Fusion

ISSN

0029-5515

e-ISSN

1741-4326

Volume of the periodical

63

Issue of the periodical within the volume

5

Country of publishing house

AT - AUSTRIA

Number of pages

11

Pages from-to

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UT code for WoS article

000960232600001

EID of the result in the Scopus database

2-s2.0-85151555439