论文标题
使用光束模型验证和优化多普勒反向散射测量的不匹配公差
Validating and optimising mismatch tolerance of Doppler backscattering measurements with the beam model
论文作者
论文摘要
我们使用以前源自光束跟踪和互惠定理的多普勒反向散射（DBS）的光束模型来阐明不匹配衰减。当探针梁的电场的波向量不在垂直于磁场的平面中时，会发生反向散射信号的衰减。纠正此效果对于确定实际密度波动的幅度很重要。模型与大型室球形托卡马克（桅杆）等离子体之间的先前初步比较是有希望的。在这项工作中，我们定量地说明了对传统Tokamak DIII-D的影响。我们比较了各种DIII-D，MAST和MAST-U等离子体中预测和测量的不匹配衰减，表明梁模型适用于多种情况。最后，我们进行了初步参数扫描，发现可以通过优化发射时优化探针梁的宽度和曲率来提高不匹配公差。对于新的DBS系统来说，这可能是设计考虑因素。
We use the beam model of Doppler backscattering (DBS), which was previously derived from beam tracing and the reciprocity theorem, to shed light on mismatch attenuation. This attenuation of the backscattered signal occurs when the wavevector of the probe beam's electric field is not in the plane perpendicular to the magnetic field. Correcting for this effect is important for determining the amplitude of the actual density fluctuations. Previous preliminary comparisons between the model and Mega-Ampere Spherical Tokamak (MAST) plasmas were promising. In this work, we quantitatively account for this effect on DIII-D, a conventional tokamak. We compare the predicted and measured mismatch attenuation in various DIII-D, MAST, and MAST-U plasmas, showing that the beam model is applicable in a wide variety of situations. Finally, we performed a preliminary parameter sweep and found that the mismatch tolerance can be improved by optimising the probe beam's width and curvature at launch. This is potentially a design consideration for new DBS systems.
