Power law spectra and intermittent fluctuations due to uncorrelated Lorentzian pulses

被引：15
作者：
Garcia, O. E. [1 ]
Theodorsen, A. [1 ]
机构：
[1] UiT, Dept Phys & Technol, N-9037 Tromso, Norway
来源：
PHYSICS OF PLASMAS | 2017年 / 24卷 / 02期
关键词：
CONFINEMENT;
D O I：
10.1063/1.4975645
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 stochastic model for intermittent fluctuations due to a super-position of uncorrelated Lorentzian pulses is presented. For a constant pulse duration, this is shown to result in an exponential power spectral density for the stationary process. A random distribution of pulse durations modifies the frequency spectrum, and several examples are shown to result in power law spectra. The distribution of pulse durations does not influence the characteristic function and thus neither the moments nor the probability density function of the random variable. It is demonstrated that the fluctuations are intrinsically intermittent through a large excess kurtosis moment in the limit of weak pulse overlap. These results allow for estimation of the basic properties of fluctuations from measurement data and describe the diversity of frequency spectra reported from measurements in magnetized plasmas. Published by AIP Publishing.
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页数：5
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