Isotope dependence of the type i ELMy H-mode pedestal in JET-ILW hydrogen and deuterium plasmas

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2021-04

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Mcode

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en

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Nuclear Fusion, Volume 61, issue 4

Abstract

The pedestal structure, edge transport and linear MHD stability have been analyzed in a series of JET with the ITER-like wall hydrogen (H) and deuterium (D) type I ELMy H-mode plasmas. The pedestal pressure is typically higher in D than in H at the same input power and gas rate, with the difference mainly due to lower density in H than in D (Maggi et al (JET Contributors) 2018 Plasma Phys. Control. Fusion 60 014045). A power balance analysis of the pedestal has shown that higher inter-ELM separatrix loss power is required in H than in D to maintain a similar pedestal top pressure. This is qualitatively consistent with a set of interpretative EDGE2D-EIRENE simulations for H and D plasmas, showing that higher edge particle and heat transport coefficients are needed in H than in D to match the experimental profiles. It has also been concluded that the difference in neutral penetration between H and D leads only to minor changes in the upstream density profiles and with trends opposite to experimental observations. This implies that neutral penetration has a minor role in setting the difference between H and D pedestals, but higher ELM and/or inter-ELM transport are likely to be the main players. The interpretative EDGE2D-EIRENE simulations, with simultaneous upstream and outer divertor target profile constraints, have indicated higher separatrix electron temperature in H than in D for a pair of discharges at low fueling gas rate and similar stored energy (which required higher input power in H than in D at the same gas rate). The isotope dependence of linear MHD pedestal stability has been found to be small, but if a higher separatrix temperature is considered in H than in D, this could lead to destabilization of peeling-ballooning modes and shrinking of the stability boundary, qualitatively consistent with the reduced pedestal confinement in H.

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| openaire: EC/H2020/633053/EU//EUROfusion

Keywords

confinement, H-mode, isotope effect, JET-ILW, pedestal, tokamak

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Citation

Horvath, L, Maggi, C F, Chankin, A, Saarelma, S, Field, A R, Aleiferis, S, Belonohy, E, Boboc, A, Corrigan, G, Delabie, E G, Flanagan, J, Frassinetti, L, Giroud, C, Harting, D, Keeling, D, King, D, Maslov, M, Matthews, G F, Menmuir, S, Silburn, S A, Simpson, J, Sips, A C C, Weisen, H, Gibson, K J & JET Contributors 2021, ' Isotope dependence of the type i ELMy H-mode pedestal in JET-ILW hydrogen and deuterium plasmas ', Nuclear Fusion, vol. 61, no. 4, 046015 . https://doi.org/10.1088/1741-4326/abdd77