A multichannel, frequency-modulated, tunable Doppler backscattering and reflectometry system.
A multichannel, frequency-modulated, tunable Doppler backscattering and reflectometry system.
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DOI：
10.1063/1.3205449
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发表时间：
2009-08
期刊：
影响因子：
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通讯作者：
J. Hillesheim;W. Peebles;T. Rhodes;L. Schmitz;T. Carter;P. Gourdain;G. Wang
中科院分区：
文献类型：
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作者：
J. Hillesheim;W. Peebles;T. Rhodes;L. Schmitz;T. Carter;P. Gourdain;G. Wang
本文介绍了一种新的多通道多普勒后向散射系统的设计和试验。Luxon，Fusion Sci. Technol.48，828（2005）]和国家球形环实验（NSTX）[M. Ono等人，Nucl. Fusion 40，557（2000）]融合等离子体装置。多普勒反向散射测量局部中间波数（k（垂直）rho（i）约1-4，k（垂直）约2-15 cm（-1））密度波动和湍流结构的传播速度。微波辐射以接近等离子体中的截止层的频率并且以倾斜于截止层的角度发射。布拉格背散射发生在截止层附近，对于k（垂直）约为-2k（i）的波动，其中k（i）是散射位置处的入射探测波矢量。湍流传播速度可以从返回信号中的多普勒频移以及散射波数的知识来确定。光线跟踪模拟用于确定k（垂直）和散射位置。电压控制的固态微波源的频率调制，然后由频率倍增被用来创建一个阵列的精细间隔（Δ f=350 MHz）的频率跨越1.4 GHz。阵列带宽的中心在大约53-78 GHz的范围内是可调谐的。本文详细介绍了系统设计，实验室测试，并提出了DIII-D等离子体的初始数据。
A novel multichannel Doppler backscattering system has been designed and tested for application on the DIII-D [J. L. Luxon, Fusion Sci. Technol. 48, 828 (2005)] and National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40, 557 (2000)] fusion plasma devices. Doppler backscattering measures localized intermediate wavenumber (k(perpendicular)rho(i) approximately 1-4,k(perpendicular) approximately 2-15 cm(-1)) density fluctuations and the propagation velocity of turbulent structures. Microwave radiation is launched at a frequency that approaches a cutoff layer in the plasma and at an angle that is oblique to the cutoff layer. Bragg backscattering occurs near the cutoff layer for fluctuations with k(perpendicular) approximately -2k(i), where k(i) is the incident probe wave vector at the scattering location. The turbulence propagation velocity can be determined from the Doppler shift in the return signal together with knowledge of the scattering wavenumber. Ray tracing simulations are used to determine k(perpendicular) and the scattering location. Frequency modulation of a voltage-controlled solid state microwave source followed by frequency multiplication is used to create an array of finely spaced (Delta f=350 MHz) frequencies spanning 1.4 GHz. The center of the array bandwidth is tunable within the range of approximately 53-78 GHz. This article details the system design, laboratory tests, and presents initial data from DIII-D plasmas.