Isotope dependence of the type I ELMy H-mode pedestal in JET-ILW hydrogen and deuterium plasmas. (9th March 2021)

• Record Type: Journal Article
• Authors: 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,
• Is Part Of: Nuclear fusion. Volume 61:Number 4(2021)
• Publication Date: 2021-03-09
• Subjects: tokamak -- isotope effect -- H-mode -- pedestal -- confinement -- JET-ILW; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/1741-4326/abdd77
• Languages: English
• ISSNs: 0029-5515

Abstract

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.