First experimental tests of a new small angle slot divertor on DIII-D

Nuclear Fushion

article

H.Y. Guo¹  H.Q. Wang¹  J.G. Watkins²  L. Casali¹  B. Covele¹  A.L. Moser¹  T. Osborne¹  C.M. Samuell³  M.W. Shafer⁴  P.C. Stangeby⁵  D.M. Thomas¹  J. Boedo⁶  R.J. Buttery¹  R. Groebner¹  D.N. Hill¹  L. Holland¹  A.W. Hyatt¹  A.E. Jaervinen³  A. Kellman¹  L.L. Lao¹  C.J. Lasnier³  A.W. Leonard¹  C. Murphy¹  J. Ren⁷  C.F. Sang⁸  A.C. Sontag⁴  T.S. Taylor¹ 

[1] General Atomics;Sandia National Laboratory;Lawrence Livermore National Laboratory;Oak Ridge National Laboratory;University of Toronto;University of California at San Diego;University of Tennessee;Dalian University of Technology

关键词: advanced divertor;    plasma-material interactions;    tokamak;    DIII-D;   

DOI  :  10.1088/1741-4326/ab26ee

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

A new small angle slot (SAS) divertor concept has been developed to enhance neutral cooling across the divertor target by coupling a closed slot structure with appropriate target shaping. Initial tests on DIII-D find a strong interplay between such anticipated 'SAS' effects and cross-field drifts, favouring operation with the ionB    ×   ∇ Bdrift away from theX -point, as currently employed for advanced tokamaks. This offers the following key improvements relative to DIII-D's open lower divertor or partially-closed upper divertor: (i) SAS allows for transition to low temperature moderately detached divertor conditions withT _e  ≲  10 eV at very low main plasma densities, lower than are usually attainable at all in DIII-D high confinement (H-mode) plasmas as used in these tests; (ii) Pedestal performance and core confinement are significantly improved with SAS. The final confinement collapse associated with the onset ofX -point MARFE (multifaceted asymmetric radiation from the edge) following deep detachment occurs at significantly higher pedestal densities, thus widening the window of H-mode operation compatible with a dissipative divertor. For operation with the ionB    ×   ∇ Bdrift toward theX -point, the divertor plasma transitions to a bifurcative detached state at much higher densities, similar to other divertor configurations in DIII-D. These results highlight the strong interplay between divertor closure and drifts, and point to an interesting divertor optimization path to explore that offers potential for future fusion reactors.

【 授权许可】

Unknown