Cross-field and parallel dynamics of SOL filaments in TCV

Nuclear Fushion

article

D. Mancini¹  N. Offeddu²  W. Han³  C. Theiler²  T. Golfinopoulos³  J.L. Terry³  E. Marmar³  C. Wüthrich²  C.K. Tsui⁴  H. de Oliveira²  B.P. Duval²  D. Galassi²  D.S. Oliveira² 

[1] Università degli Studi della Tuscia, Largo dell’Università s.n.c.;Ecole Polytechnique Fédérale de Lausanne ,(EPFL), Swiss Plasma Center;MIT, Plasma Science and Fusion Center;UCSD, Center for Energy Research

关键词: filamentary turbulence;    SOL turbulence;    cross-field transport;    blobs;    two-regionmodel;    turbulent transport regime;    parallel dynamics;   

DOI  :  10.1088/1741-4326/ac7ed7

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

Using recently installed scrape-off layer diagnostics on the tokamak à configuration variable, we characterise the poloidal and parallel properties of turbulent filaments. We access both attached and detached divertor conditions across a wide range of core densities ( f _G ∈ [0.09, 0.66]) in diverted L-mode plasma configurations. With a gas puff imaging (GPI) diagnostic at the outer midplane we observed filaments with a monotonic increase in radial velocity (from 390 m s⁻¹ to 800 m s⁻¹) and cross-field radii (from 8.5 mm to 13.4 mm) with increasing core density. Interpreting the filament behaviour in the context of the two-region model by Myraet al(2006Phys. Plasmas13112502), we find that they populate the ideal-interchange regime ( C _i) in discharges at very low densities, and the resistiveX( RX )-point regime for all other discharges. The scaling of filament velocity versus size shows good agreement with this interpretation. These results are discussed and compared with previous probe-based measurements for similar conditions, which mostly placed filaments in TCV in the resistive ballooning ( RB ) regime (Tsuiet al2018Phys. Plasmas25072506). In addition, for the first time in TCV, the parallel filament extension is studied by magnetically aligning the GPI measurements at the outboard midplane with a reciprocating probe in the divertor. In agreement with the filaments being in the ideal-interchange and the RX-point regimes, they are found to extend beyond the X-point into the outer divertor leg.

【 授权许可】

Unknown