Observation of the bulk ion density peaking in a discharge with an impurity hole in the LHD

Nuclear Fushion

article

A. Perek¹  K. Ida²  M. Yoshinuma²  M. Goto²  Y. Nakamura²  M. Emoto²  R. Jaspers¹  LHD Experiment Group² 

[1] Eindhoven University of Technology;National Institute for Fusion Science

关键词: LHD;    charge exchange spectroscopy;    helium exhaust;    impurity transport;    impurity hole;   

DOI  :  10.1088/1741-4326/aa6c51

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

Radial profiles of bulk ion and impurity ions density are simultaneously measured and quantified using charge exchange spectroscopy and peaking parameter, {{C}_{ext{v}}} . The peaking parameter is positive for inward and negative for outward convection in a plasma with an impurity hole in the Large Helical Device. Following the formation of an impurity hole associated with the transition from L-mode to ion ITB plasma, the bulk ion becomes peaked by the inward convection 0right)$ " align="top">left({{C}_{ext{v}}}>0right) , while impurities (helium and carbon) become hollow due to the outward convection left({{C}_{ext{v}}}<0right) . In contrast to the ion ITB plasma, in the L-mode plasma the impurity profiles are peaked 0right)$ " align="top">left({{C}_{ext{v}}}>0right) , where the bulk ion density profile remains flat left({{C}_{ext{v}}}sim 0right) . Understanding of the impurity behavior in the ion ITB plasma could lead to a self cleaning plasma reactor concept, with an efficient impurity exhaust.

【 授权许可】

Unknown