发表机构
Agency for Science, Technology and Research (A*STAR); Nanyang Technological University; University of California, Los Angeles (UCLA)（科学与技术研究局; 南洋理工大学; 加州大学洛杉矶分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究比较用垂直位移和极向角扫描进行湍流谱的DBS测量，借助Scotty合成诊断评估两种方法异同，发现垂直位移扫描有优势，能提供可比覆盖范围且减少对放电重复性依赖，确立其为单次DBS波数谱实用途径。
AI 中文摘要
多普勒背散射（DBS）测量电子密度波动。通常通过改变探测束的极向发射角来改变测量的波数。由于大多数DBS系统在一次放电期间无法转向，因此需要重复放电并在每次放电之间改变极向角。另一种方法是保持DBS发射角固定，而是上下移动等离子体，从而在单次放电内测量一系列波数。我们称之为弹跳球方法。我们使用Scotty合成诊断（Hall-Chen，2022）来评估这两种方法之间的异同。两种方法都能够测量相似范围的波动波数以及径向位置。然而，垂直位移扫描的测量极向位置范围比极向角扫描更大。使用相同的合成湍流谱作为输入，我们表明由于不同的仪器功能，这两种方法预计具有不同的背向散射功率。当通过合成诊断考虑失配衰减时，垂直位移扫描可以提供可比的径向和波数覆盖范围，同时减少对逐次放电重复性的依赖。这些结果确立了垂直位移扫描作为单次DBS波数谱的实用途径。
英文摘要
Doppler backscattering (DBS) measures electron density fluctuations. The measured wavenumber is typically varied by changing the probe beam poloidal launch angle. As most DBS systems are unable to steer during a shot, the shot is repeated and the poloidal angle is changed intershot. An alternative method is to keep the DBS launch angle fixed and move the plasma up and down instead, enabling a range of wavenumbers to be measured within a single shot. We call this the bouncing ball method. We use the Scotty synthetic diagnostic (Hall-Chen, 2022) to evaluate the similarities and differences between these two approaches. Both approaches are capable of measuring a similar range of fluctuation wavenumbers as well as radial locations. However, the vertical-displacement scan has a larger range of measured poloidal locations than the poloidal-angle scan. Using the same synthetic turbulence spectrum as input, we show that the two approaches are expected to have different backscattered powers due to different instrumentation functions. When mismatch attenuation is accounted for via a synthetic diagnostic, the vertical-displacement scan can provide comparable radial and wavenumber coverage while reducing reliance on shot-to-shot repeatability. These results establish vertical-displacement scan as a practical route to single-shot DBS wavenumber spectra.
