Reliability of the two-point measurement of the spatial correlation length from Gaussian-shaped fluctuating signals in fusion-grade plasmas

被引：4

作者：

Kim, Jaewook ^{[1
]}

Nam, Y. U. ^{[2
]}

Lampert, M. ^{[3
]}

Ghim, Y. -C. ^{[1
]}

机构：

[1] Korea Adv Inst Sci & Technol, Dept Nucl & Quantum Engn, Daejeon 34141, South Korea

[2] Natl Fus Res Inst, Daejeon, South Korea

[3] Euratom Assoc HAS, Wigner RCP, Budapest, Hungary

来源：

NUCLEAR FUSION | 2016年 / 56卷 / 10期

基金：

新加坡国家研究基金会;

关键词：

turbulence; two-points correlation measurement; KSTAR; beam emission spectroscopy; WAVE-NUMBER; TURBULENCE; SPECTRUM;

D O I：

10.1088/0029-5515/56/10/106016

中图分类号：

O35 [流体力学]; O53 [等离子体物理学];

学科分类号：

070204 ; 080103 ; 080704 ;

摘要：

A statistical method for the estimation of the spatial correlation lengths of Gaussian-shaped fluctuating signals with two measurement points is examined to quantitatively evaluate its reliability (variance) and accuracy (bias error). The standard deviation of the correlation value is analytically derived for randomly distributed Gaussian shaped fluctuations satisfying stationarity and homogeneity, allowing us to evaluate, as a function of fluctuation-to-noise ratios, the sizes of averaging time windows and the ratios of the distance between the two measurement points to the true correlation length, and the goodness of the two-point measurement for estimating the spatial correlation length. Analytic results are confirmed with numerically generated synthetic data and real experimental data obtained with the KSTAR beam emission spectroscopy diagnostic. Our results can be applied to Gaussian-shaped fluctuating signals where a correlation length must be measured with only two measurement points.

引用

页数：15