YASAKA Yasuyoshi FACULTY ENG., KYOTO UNIV., ASSOC.PROFESSOR, 工学部, 助教授 (30109037)
犬竹 正明 筑波大学, 物理工学系, 助教授 (90023738)
SAITO Teruo INSTITUTE OF PHYSICS,ASSOC.PROFESSOR, 物理学系, 助教授 (80143163)
KIWAMOTO Yasuhito INST.OF APPLIED PHYSICS,ASSOC.PROFESSOR, 物理工学系, 助教授 (50018040)
|Budget Amount *help
¥20,500,000 (Direct Cost : ¥20,500,000)
Fiscal Year 1994 : ¥2,500,000 (Direct Cost : ¥2,500,000)
Fiscal Year 1993 : ¥18,000,000 (Direct Cost : ¥18,000,000)
The purpose of this research program is to investigate physical mechanisms of rapid energy transort along magnetic field lines in plasmas under controlled experimental conditions. This type of heat transport is observed in a variety of magnetized plasmas, and it is closely connected with the formation of potential distribution along the open field lines. The experiments are made in the large-scale west end plasma region in the GAMMA10 tandem mirror in PRC,Univ.of Tsukuba. The control knobs, developed for the experiment, are 2.45GHz Electron Cyclotron Resonance Heating (ECRH) system for THERMAL DIKE and MESH BIAS system. Special concern in this study lies in convective heat transport associated with particle exchange of hot electrons that hit end plates with cold electrons abundantly produced via secondary emissions. TD enhances magnetic mirror reflections and MB increases electrostatic reflection of the cold electrons so as to reduce the exchange rate of the two classes of electrons. M
B deepens the depth of floating potential of the endplates, so that the warm electron flux reaching the endplates decreases to about a half. The effective temperature of the electrons increases with MB.Most of the heat flux is attributed to the convective electron transport because the ion flux remains much smaller than the flux of impinging primary electrons. The reduction of the heat load to the plate is also observed with a thermo-couple arry and with infra-red camera. These results demonstrate the effectiveness of MB in reducing the heat flux in plasmas. But, since the decrement of the temperature-rise is smaller than that evaluated from the particle analyzes, further tests are required on the temperature diagnostics. It may also indicate that other heat channels are active than those watched with the particle analyzers.
TD deepens the endplate potential by about 10% while the primary electron flux does not always decrease. The endplate temperature tends to decrease as a whole, though under some plasma conditions it increases, These observations motivated detailed analyzes of dynamics of primary electrons under ECRH.Using newly developed theoretical tools of a potential model and heating response function, we found that these electrons are transformed to Yushmanov particles subject to multiple heating and partially driven to the endplates, increasing heat-load. Local tailoring of the magnetic field profile at the resonance is found to be effective in increasing the benefit of TD.