| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 1999: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1998: ¥2,700,000 (Direct Cost: ¥2,700,000)
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| Research Abstract |
As a result of this investigation, we got more detailed data concerning the nonlinearly developing process of the plasma disruption caused by the sear of rotating angular velocity, which was obtained preliminary last year.
1. In order to test the method observing the behavior of the plasma density on the plane perpendicular to the magnetic field by the multi probes developed last year, we have applied this method to the drift waves, and succeeded to get the preliminary data of the drift-wave vortices drifting with the speed of the drift wave. Thus, we could show the high ability of this 2D measuring system. Unfortunately, we could not succeed the 2D observation of the sawtooth oscillation and the plasma disruption, although we observed the plasma diffusion in a shear of rotating angular velocity. This is because the lack of reproducibility as a results of insufficient controlling the sawtooth oscillation and the plasma disruption. Now, we are making an effort to improve this point.
2. Thus, we observed, not the 2D contour lines date, but the direct date from the multi probes by using the oscilloscope, and discussed the relation between the sawtooth oscillation and the plasma disruption in detail. As a results of investigation, it became clear that there exist 4 regions determined by the strength of radial electric field: 1) the region of linear m=2 mode excitation, 2) the region of simultaneously excited m=1 and m=2 modes, 3) the region of alternatively appearance of m=1 and m=2 modes, 4) the region that m=1 becomes sawtooth oscillation and the plasma disruption takes place. The region 4) considerably resembles the Tokamak behavior of the tearing instability and the plasma disruption. Our data show the importance of the nonlinear developing process where m=1 mode overcomes m=2 mode and induces the plasma disruption.
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