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Oct 13 – 18, 2014
Hotel Park Inn Pribaltiyskaya
Europe/Moscow timezone

Attainment of High Electron Poloidal Beta in Axisymmetric State and Two Routes to Self-Organized Helical State in Low-Aspect-Ratio RFP

Oct 15, 2014, 8:30 AM
4h
Green 8-9 (Hotel Park Inn Pribaltiyskaya)

Green 8-9

Hotel Park Inn Pribaltiyskaya

Saint Petersburg, Russian Federation
Poster Poster 3

Speaker

Prof. Sadao Masamune (Kyoto Institute of Technology)

Description

Improvement of plasma performance has been advanced in the low-aspect-ratio (low-A) reversed field pinch (RFP) RELAX, whose main objectives include exploring the low-A RFP configuration. In axisymmetric RFP states in deep-reversal region, it is found that central electron poloidal beta, beta_p (=p_e0/(B_pa^2/(2mu_0))), which almost equals the electron beta in the RFP, has reached to 5~10%. Feedback control using saddle coil array is applied to stabilize a single resistive wall mode (RWM). As a result, fine tuning of the equilibrium becomes effective in achieving the resultant beta_p of higher than 10%. The attained parameter region is close to where we expect sizable fraction of the bootstrap current which is characteristic to low-A RFP configuration. In shallow-reversal region characterized by relaxation to the quasi-single helicity (QSH) state, soft-X ray (SXR) computed tomography (CT) technique has revealed helically deformed m/n=1/4 structure of SXR emissivity profile. 3-D MHD simulation using the MIPS code has shown two possible routes to the self-organized helical state depending on the initial equilibrium; one through core-resonant tearing mode, and the other through internally non-resonant kink mode. The self-organized helical structure agrees well with experimental results.
Country or International Organisation Japan
Paper Number EX/P3-52

Primary author

Prof. Sadao Masamune (Kyoto Institute of Technology)

Co-authors

Dr Akio Sanpei (Kyoto Institute of Technology) Dr Daniel Den Hartog (University of Wisconsin-Madison) Mr Go Ishii (Kyoto Institute of Technology) Dr Haruhiko Himura (Kyoto Institute of Technology) Dr Haruhisa Koguchi (AIST) Mr Hiroyuki Tanaka (Kyoto Institute of Technology) Ms Kanae Nishimura (Kyoto Institute of Technology) Prof. Katsuji ICHIGUCHI (National Institute for Fusion Science) Dr Naoki Mizuguchi (National Institute for Fusion Science) Dr Roberto Paccagnella (Consorzio RFX and Consiglio Nazionale delle Ricerche (CNR)) Mr Ryosuke Kodera (Kyoto Institute of Technology) Mr Ryota Ueba (Kyoto Institute of Technology) Dr Tsuyoshi Akiyama (National Institute for Fusion Science) Prof. kazuo kawahata (National Institute for Fusion Science)

Presentation materials