Schmitz L, Wang G, Hillesheim J C, Rhodes T L, Peebles W A, White A E, Zeng L, Carter T A, Solomon W
UCLA Physics and Astronomy Department, Los Angeles, California 90095-1547, USA.
Rev Sci Instrum. 2008 Oct;79(10):10F113. doi: 10.1063/1.2953675.
Doppler backscattering (DBS) has been successfully used to measure the E x B flow velocity and local intermediate wavenumber density fluctuation levels in the DIII-D tokamak. Depending on the launch angle and the frequency of the probing beam, the signal backscattered from the plasma cut-off layer is sensitive to density fluctuations at a specific perpendicular wavenumber (1 < or = k(perpendicular rho(s)) < or = 4). Due to the localization and high time resolution for poloidal flow measurements, DBS is well suited to detect stationary and time-dependent shear flows [zonal flows (ZFs)]. We present a novel scheme to measure ZF spectra using a dual-channel DBS system capable of simultaneously probing two minor radii separated by a distance of 0.2 cm < Delta r < 3 cm. Frequency spectra of geodesic acoustic modes and low frequency ZFs (f or = 10 kHz) have been obtained for 0.6 < r/a < 0.95.
多普勒背散射（DBS）已成功用于测量DIII-D托卡马克中的E×B流速度和局部中间波数密度涨落水平。根据探测光束的发射角度和频率，从等离子体截止层反向散射的信号对特定垂直波数（1≤k⊥ρs≤4）处的密度涨落敏感。由于其在极向流测量中的局域性和高时间分辨率，DBS非常适合检测稳态和随时间变化的剪切流[带状流（ZF）]。我们提出了一种新颖的方案，使用双通道DBS系统测量ZF谱，该系统能够同时探测两个相距0.2 cm＜Δr＜3 cm的小半径。对于0.6＜r/a＜0.95，已获得测地声模和低频ZF（f≤10 kHz）的频谱。
