2005 Fiscal Year Final Research Report Summary
Generalized Physics Mechanisms of Plasma Confinement with Radially Sheared Electric Field Formation by High Power ECH and Verification of Newly Developed Plasma Stabilization Method
Grant-in-Aid for Scientific Research (B)
|Allocation Type||Single-year Grants |
Nuclear fusion studies
|Research Institution||University of Tsukuba |
CHO Teruji Univ.Tsukuba, Graduate School of Pure and Applied Sciences, Professor -> 筑波大学, 大学院・数理物質科学研究科, 教授 (80171958)
YASAKA Yasuyoshi Kobe Univ., Faculty of Engineering, Professor, 工学部・電気電子工学科, 教授 (30109037)
IMAI Tsuyoshi Univ.Tsukuba, Graduate School of Pure and Applied Sciences, Professor, 大学院・数理物質科学研究科, 教授 (80354637)
SAKAMOTO Keishi Japan Atomic Energy Agency, Fusion Research and Development Directorate, Group Leader, 核融合研究開発部門, 主任研究員 (90343904)
KOHAGURA Junko Univ.Tsukuba, Graduate School of Pure and Applied Sciences, Assistant Professor, 大学院・数理物質科学研究科, 講師 (60302345)
HIRATA Mafumi Univ.Tsukuba, Graduate School of Pure and Applied Sciences, Assistant Professor, 大学院・数理物質科学研究科, 講師 (70222247)
|Project Period (FY)
2004 – 2005
|Keywords||tandem mirror / plasma / nulcear fusion / potential / x-ray / high power ECH / plasma confinement / stabilization|
1.Four-time progress in ion-confining potential height (φ_c) through these years is achieved in the hot-ion mode with an ion temperature of several keV having the favorably increasing scaling of φ_c with plug electron-cyclotron heating (ECH) powers.
2.The advance in the potential formation leads to a finding of remarkable effects of radially sheared electric fields on turbulence suppression and transverse-loss reduction.
3.A preferable dependence of a weak decrease in φ_c with increasing density ranging to 〜10^<19> m^<-3> along with the recovery of φ_c with increasing plug ECH powers is obtained.
4.A transverse energy-transport barrier is produced by off-axis ECH in a barrier mirror for the first time, with the formation of a cylindrical layer having energetic electrons flowing through the whole device. This leads to suppress intermittent turbulent vortex-like structures near the layer, and results in electron temperature and ion temperature rises surrounded by the layer having a localized bumped ambipolar potential Φ_c. The radial transport barrier is explained by the formation of a strong E_r shear or peaked vorticity W with the direction reversal of E_r×B sheared flow near the Φ_c peak for the turbulence suppression.
5.Preliminary central ECH (170kW,20ms) in a standard tandem-mirror operation raises T_<eO> from 70 to 300 eV together with T_<i⊥O> from 4.5 to 6.1 keV, and T_<i//O> from 0.5 to 1.2 keV with τ_<pO>=95 ms for φ_c(=1.4 kV) trapped ions. The on-axis particle to energy confining ratio of τ_<pO>/τ_<EO> is observed to be 1.7 for φ_c trapped ions (consistent with Pastukhov's theory) and 2.4 for central mirror-trapped ions with 240-kW plug ECH and 90-kW ICH (η_<ICH>〜0.3;nl_c=4.5×10^<17>m^<-2>).
Research Products (13 results)