Effects of Radially Sheared Electric Field on Turbulence Reduction Analyzed with End-Loss Analysing Systems

• Published in: Plasma and Fusion Research 2007, Vol.2, pp.S1077-S1077
• Main Authors: HIRATA, Mafumi, CHO, Teruji, KOHAGURA, Junko, NUMAKURA, Tomoharu, KIMINAMI, Serina, ITO, Marie, MORIMOTO, Naoyuki, HIRAI, Katsuaki, YAMAGISHI, Tooru, IKUNO, Toshinori, NAMIKI, Shohei, MIYATA, Yoshiaki, MINAMI, Ryutaro, OGURA, Kazuo, KONDOH, Takashi, KARIYA, Tsuyoshi, IMAI, Tsuyoshi, MIYOSHI, Syoichi
• Format: Article
• Language: English
• Subjects: electron-cyclotron heating; end-loss analyzer; radially sheared electric field; tandem mirror; transport-barrier
• ISSN: 1880-6821; 1880-6821
• DOI: 10.1585/pfr.2.S1077

Mirror devices, having open-ended regions, provide intrinsic important advantages in terms of the control of radial-potential or Er shear profiles on the basis of axial particle loss control for ambipolar potential formation. From the viewpoint of the mechanism investigation of radially localized transport-barrier formation, an idea of off-axis-resonant electron-cyclotron heating (ECH) is proposed and applied in the tandem mirror GAMMA 10, by the use of the aforementioned intrinsic advantage of mirror devices. The off-axis ECH produces a cylindrical layer with energetic electrons and facilitates the formation for a localized bumped ambipolar potential with a strong shear of radial electric fields Er. Remarkable effects of dEr/dr on the suppression of turbulent fluctuations with plasma confinement improvement are found by the use of signals of end-loss currents flowing from the central cell as well as the central-cell soft x ray. In association with the reduction of the fluctuations due to strong Er shear formation, increases in ion and electron temperatures are found.