On the role of spectral resolution in velocity shear layer measurements by Doppler reflectometry.
On the role of spectral resolution in velocity shear layer measurements by Doppler reflectometry.
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DOI：
10.1063/1.3464475
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发表时间：
2010-10
期刊：
影响因子：
--
通讯作者：
T. Happel;E. Blanco;T. Estrada
中科院分区：
文献类型：
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作者：
T. Happel;E. Blanco;T. Estrada
多普勒反射仪的信号质量很大程度上取决于其光谱分辨率，而光谱分辨率又受微波光束特性和等离子体截止层曲率半径的影响。如果在强垂直速度剪切层附近测量，背向散射信号的频谱会受到不同速度的影响。这会在光谱中产生两个多普勒频移的峰，就像在TJ-II H模等离子体中观察到的那样。二维全波模拟表明，在系统的光谱分辨率足够的情况下，两个峰是可分离的。然而，如果光谱分辨率很低，两个峰会混合成一个峰，并产生一个中间的和不正确的速度。
The signal quality of a Doppler reflectometer depends strongly on its spectral resolution, which is influenced by the microwave beam properties and the radius of curvature of the cutoff layer in the plasma. If measured close to a strong perpendicular velocity shear layer, the spectrum of the backscattered signal is influenced by different velocities. This can give rise to two Doppler shifted peaks in the spectrum as observed in TJ-II H-mode plasmas. It is shown by two-dimensional full wave simulations that the two peaks are separable provided the spectral resolution of the system is sufficient. However, if the spectral resolution is poor, the two peaks blend into one and yield an intermediate and incorrect velocity.