Role of the separatrix density in the pedestal performance in deuterium low triangularity JET-ILW plasmas and comparison with JET-C

Nuclear Fushion

article

L. Frassinetti¹  C. Perez von Thun²  B. Chapman³  A. Fil³  J.C. Hillesheim³  L. Horvath³  G.T.A. Huijsmans⁴  H. Nyström¹  V. Parail³  S. Saarelma³  G. Szepesi³  B. Viola³  R. Bianchetti Morales³  M. Dunne⁵  A.R. Field³  J. Flanagan³  J.M. Fontdecaba⁶  D. Hatch⁷  B. Lomanowski⁸  C.F. Maggi³  S. Menmuir³  S. Pamela³  C.M. Roach³  E. Rachlew¹  E.R. Solano⁶  JET Contributors⁹ 

[1] Division of Fusion Plasma Physics;Institute of Plasma Physics and Laser Microfusion;CCFE, Culham Science Centre;CEA;Max-Planck-Institut für Plasmaphysik;Laboratorio Nacional de Fusión;Institute for Fusion Studies, University of Texas at Austin;Oak Ridge National Laboratory;EUROfusion Consortium, JET, Culham Science Centre

关键词: pedestal;    JET;    peeling-ballooning stability;    EPED;    Europed;    separatrix density;   

DOI  :  10.1088/1741-4326/ac3363

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

A reduction of the pedestal pressure with increasing separatrix density over pedestal density ( n _e^sep/ n _e^ped) has been observed in JET. The physics behind this correlation is investigated. The correlation is due to two distinct mechanisms. The increase ofn _e^sep/ n _e^ped till ≈0.4 shifts the pedestal pressure radially outwards, decreasing the peeling-balloning stability and reducing the pressure height. The effect of the position saturates aboven _e^sep/ n _e^ped ≈ 0.4. For higher values, the reduction of the pedestal pressure is ascribed to increased turbulent transport and, likely, to resistive MHD effects. The increase ofn _e^sep/ n _e^ped above ≈0.4 reduces ∇ n _e /n _e, increasingη _e and the pedestal turbulent transport. This reduces the pressure gradient and the pedestal temperature, producing an increase in the pedestal resistivity. The work suggests that the increase in resistivity might destabilize resistive balloning modes, further reducing the pedestal stability.

【 授权许可】

Unknown