Grant-in-Aid for Scientific Research (A).
|Allocation Type||Single-year Grants|
Nuclear fusion studies
|Research Institution||Nagoya University|
TAKAMURA Shuichi Nagoya University, Graduate School of Engineering, Professor, 工学研究科, 教授 (40023254)
YE Miyou Nagoya University, Fraduate School of Engineering, Research Associate, 工学研究科, 助手 (10270985)
OHNO Noriyasu Nagoya University, Fraduate School of Engineering, Lecturer, 工学研究科, 講師 (60203890)
UESUGI Yoshihiko Nagoya University, Center for Integrated Research in Science and Engineering, Asociate Professor, 理工科学総合研究センター, 助教授 (90213339)
|Project Period (FY)
1997 – 2000
Completed(Fiscal Year 2000)
|Budget Amount *help
¥31,700,000 (Direct Cost : ¥31,700,000)
Fiscal Year 2000 : ¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1999 : ¥5,400,000 (Direct Cost : ¥5,400,000)
Fiscal Year 1998 : ¥8,600,000 (Direct Cost : ¥8,600,000)
Fiscal Year 1997 : ¥15,600,000 (Direct Cost : ¥15,600,000)
|Keywords||Fusion plasma / Engafic divertor / Magnetic island / Stachastic magnetic field / Ratating helical field / tearing mode / Magnetic Rayonlds number / Hydigen recycling / 磁気レイノルズ数 / トカマク / 統計電磁場構造 / 核融合 / 回転ヘリカル磁場 / 統計的磁場 / プラズマ回転 / プラズマ粘性|
1. Hydrogen recycling in long-pulse tokamak discharge
By applying the static or rotating helical magnetic field, the surface area contacting with the plasma was found to increase so that the fresh wall surface enhances the wall pumping.
2. Magnetic island formation due to rotating helical magnetic perturbation
When the relative poloidal velocity between the tokamak plasma and the rotating helical field is relatively small, the growth of tearing-mode by magnetic reconnection produces finally the formation of magnetic island. It deforms the equilibrium magnetic flux surface so that the plasma current may be modulated in radial and poloidal directions. Such a modulation has been detected through an amplification of perturbed radial magnetic field. The redistribution of plasma current due to magnetic island development has been clearly observed at the main resonance layer of magnetic helicity.
3. Enhanced attenuation of penetrating perturbed magnetic field
When the relative poloidal velocity me
ntioned in the previous section is large and the electron temperature at the resonance layer is relatively high, the screening current flows at this resonance layer so that a strong attenuation of penetrating external magnetic perturbation has been observed. The magnetic perturbation with a fixed frequency produces either a magnetic island formation or an attenuation of helical field, depending on the direction of field rotation. Such an attenuation has been thought not only by a main resonance at m/n=6/1 but also by some contributions from the side-band modes of m/n=7/1, 8/1 generated by the toroidal effect, which has been investigated numerical modelling.
4. Temporal modulation of electron temperature profile
The deformation of magnetic flux surface due to island formation generates temporal modulation of the radial profile of electron temperature. The effect with and without magnetic island formation may produces different behaviors, which has been investigated now.
5. Excitation of shear Alfven waves and other phenomena
The shear Alfven resonance is located at very close to the magnetic resonance layer. The magnetic field enhancement due to Alfven resonance has been tried to be detected by observing the radial component of perturbed magnetic field at a toroidal section without local helical winding. There have been observed some enhancement close to the Alfven resonance layer. The phase information on the 2-D poloidal cross-section has been investigated to make clear the contribution of Alfven resonance. Less