Ultrafast millimeter-wave frequency-modulated continuous-wave reflectometry for NSTX
Ultrafast millimeter-wave frequency-modulated continuous-wave reflectometry for NSTX
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DOI：
10.1063/1.2351894
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发表时间：
2006-10
影响因子：
1.6
通讯作者：
S. Kubota;W. Peebles;X. V. Nguyen;N. Crocker;A. Roquemore
中科院分区：
文献类型：
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作者：
S. Kubota;W. Peebles;X. V. Nguyen;N. Crocker;A. Roquemore
NSTX 上的毫米波调频连续波 (FM-CW) 反射计是一个多通道系统，提供电子密度剖面测量，频率覆盖范围为 13–53GHz [相应的 O 模密度范围为 (0.21–3.5)×1013cm−3]。最近，该系统经过修改，可实现超快全频段扫描，重复间隔低至 10μs。为了使该系统发挥波动诊断的作用，消除由频率扫描中的非线性引起的相位导数中的伪影至关重要；我们引入了一种简单的硬件技术，可以将这些伪影减少到 ≃0.3%。对于 NSTX，额外的带宽 (⩽100kHz) 极大地增强了 FM-CW 反射计诊断低频磁流体动力学不稳定性（例如，内部扭结、电阻壁模式、新古典撕裂模式以及快速粒子驱动鱼骨和低频环形阿尔芬本征模式）的能力。
The millimeter-wave frequency-modulated continuous-wave (FM-CW) reflectometer on NSTX is a multichannel system providing electron density profile measurements with a frequency coverage of 13–53GHz [corresponding O-mode density range of (0.21–3.5)×1013cm−3]. Recently, this system has been modified to allow ultrafast full-band sweeps for repetition intervals down to 10μs. For this system to function as a fluctuation diagnostic it is crucial to eliminate artifacts in the phase derivative caused by nonlinearities in the frequency sweep; we introduce a simple hardware technique for reducing these artifacts to ≃0.3%. For NSTX, the additional bandwidth (⩽100kHz) greatly enhances the capability of the FM-CW reflectometer as a diagnostic for low frequency magnetohydrodynamics instabilities (e.g., internal kinks, resistive wall modes, neoclassical tearing modes, as well as fast-particle driven fishbones and low frequency toroidal Alfven eigenmodes).