The role of ETG modes in JET–ILW pedestals with varying levels of power and fuelling

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Chapman-Oplopoiou, B. and Ben Yaala, M., JET Contributors (2022) The role of ETG modes in JET–ILW pedestals with varying levels of power and fuelling. Plasma Physics and Controlled Fusion, 62 (8). 086028. ISSN 0741-3335 (https://doi.org/10.1088/1741-4326/ac7476)

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Abstract

We present the results of GENE gyrokinetic calculations based on a series of JET–ITER-like-wall (ILW) type I ELMy H-mode discharges operating with similar experimental inputs but at different levels of power and gas fuelling. We show that turbulence due to electron-temperature-gradient (ETGs) modes produces a significant amount of heat flux in four JET–ILW discharges, and, when combined with neoclassical simulations, is able to reproduce the experimental heat flux for the two low gas pulses. The simulations plausibly reproduce the high-gas heat fluxes as well, although power balance analysis is complicated by short ELM cycles. By independently varying the normalised temperature gradients and normalised density gradients around their experimental values, we demonstrate that it is the ratio of these two quantities that determines the location of the peak in the ETG growth rate and heat flux spectra. The heat flux increases rapidly as ηe increases above the experimental point, suggesting that ETGs limit the temperature gradient in these pulses. When quantities are normalised using the minor radius, only increases in produce appreciable increases in the ETG growth rates, as well as the largest increases in turbulent heat flux which follow scalings similar to that of critical balance theory. However, when the heat flux is normalised to the electron gyro-Bohm heat flux using the temperature gradient scale length , it follows a linear trend in correspondence with previous work by different authors.

ORCID iDs

Chapman-Oplopoiou, B. and Ben Yaala, M. ORCID logoORCID: https://orcid.org/0000-0002-6754-0875;
  • Item type:Article
    ID code:86588
    Dates:
    Date
    Event
    22 June 2022
    Published
    30 May 2022
    Accepted
    Subjects:Science > Physics
    Department:Faculty of Engineering > Biomedical Engineering
    Depositing user: Pure Administrator
    Date deposited:29 Aug 2023 15:13
    Last modified:11 Nov 2024 14:04
    URI:https://strathprints.strath.ac.uk/id/eprint/86588
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