Abstract
The Large Helical Device (LHD) is the largest heliotron‐type super‐conducting fusion experimental device. One of the features of the heliotron configuration is its unique edge magnetic field topology. There exist an intrinsic stochastic layer just outside of the last closed flux surface (LCFS), residual islands embedded in the stochastic layer, whisker structures, laminar layers and intrinsic divertor structure (helical divertor). That contrasts to ‘onion‐skin’ like magnetic field structure in poloidal divertor tokamaks scrape‐off layer (SOL). The edge field line structure can be characterized by Kolmogorov length and field line connection length from wall to the other wall. In the stochastic layer, Kolmogorov length is much longer than connection length. Typical connection length of field lines in the stochastic layer and laminar layers are several kilometers and below several tens of meters, respectively, and these structures co‐exist. Therefore, the radial profile of field lines connection length becomes complex contrasting to that in poloidal divertor tokamaks SOL. Plasma transport in the LHD edge region has been studied experimentally by using Langmuir probes and Thomson scattering method, and numerically by using three dimensional plasma and neutral transport codes. In this paper, the physical basis of the heliotron configuration, especially the characteristics of the edge magnetic field topology is presented. Understandings of plasma transport in such a unique magnetic field structure are discussed.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
