Modification of the magneto-hydrodynamic equilibrium by the lower-hybrid wave driven fast electrons on the TST-2 spherical tokamak. (11th October 2021)

• Record Type: Journal Article
• Authors: Tsujii, N.; Takase, Y.; Ejiri, A.; Watanabe, O.; Yamazaki, H.; Peng, Y.; Iwasaki, K.; Aoi, Y.; Ko, Y.; Matsuzaki, K.; Rice, J.H.P.; Osawa, Y.; Moeller, C.P.; Yoshimura, Y.
• Is Part Of: Nuclear fusion. Volume 61:Number 11(2021)
• Publication Date: 2021-10-11
• Subjects: spherical tokamak -- lower-hybrid current drive -- fast electrons -- finite orbit effect -- extended magneto-hydrodynamics; Nuclear fusion -- Periodicals; 621.48405
• DOI: 10.1088/1741-4326/ac217d
• Languages: English
• ISSNs: 0029-5515

Abstract

Abstract: Presence of a large population of fast particles may qualitatively modify the tokamak equilibrium from the one that can be described by standard magneto-hydrodynamics (MHD). The kinetic modification of the MHD equilibrium was studied for a lower-hybrid (LH) wave driven plasma on the TST-2 spherical tokamak. The analysis was performed using an equilibrium reconstruction method based on an extended MHD model that considers a two-component plasma of bulk MHD fluid and kinetic fast electrons. Scrape-off-layer current appeared naturally in the extended MHD analysis because of the finite electron orbit excursion from the flux surfaces. This reduced the bulk pressure contribution to the toroidal current substantially. The resulting poloidal flux profile was more consistent with that inferred from the Thomson scattering measurement.