科研之友
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摘要
The poloidal correlation reflectometry diagnostic operated in ordinary mode with additional radial correlation channel is applied in this paper to investigate the correlation of the turbulent density fluctuations. The perpendicular and radial correlation lengths, l(perpendicular to) and l(r), the perpendicular velocity v(perpendicular to) and the dissipation (mutation) time tau(d) are measured simultaneously from the outer core to edge in the L-mode plasmas of ASDEX Upgrade. It is shown that in the outer core region (0.6 < rho(pol) < 0.9) the measured correlation lengths scale with the drift wave length, l(perpendicular to) approximate to 5 rho(s) and l(r) approximate to 10 rho(s), while the dissipation time is inversely correlated with the velocity tau(d) approximate to 40/v(perpendicular to) (tau(d) is in mu s and v(perpendicular to) in km s(-1)). In the pedestal region (0.925 < rho(pol) < 0.98), where the E x B shear flows are present, a loss of measured correlation is observed which can be explained by a combination of small propagation velocity and an additional reduction of tau(d). In the E-r well region (rho(pol) approximate to 0.99), the measured perpendicular correlation length increases l(perpendicular to) approximate to 13 rho(s) and the radial correlation length decreases l(r) approximate to 4 rho(s) compared to the outer core values. The correlation measurements are interpreted in the frame of the linear regime of reflectometry (applied only to rho(pol) < 0.9). Using the Born approximation we show that the finite wavenumber sensitivity of the reflectometer increases the measured l(perpendicular to) and l(r), but does not affect the measured tau(d). By the including diagnostic correction the real correlation lengths l(perpendicular to) approximate to l(r) approximate to 3 rho(s) are estimated.
- 出版日期2018-7
