Stochastic modelling of intermittent fluctuations in the scrape-off layer: Correlations, distributions, level crossings, and moment estimation
- Department of Physics and Technology, UiT The Arctic University of Norway, N-9037 Tromsø (Norway)
- Physics Department, University of Oslo, PO Box 1048 Blindern, N-0316 Oslo (Norway)
A stochastic model is presented for intermittent fluctuations in the scrape-off layer of magnetically confined plasmas. The fluctuations in the plasma density are modeled by a super-position of uncorrelated pulses with fixed shape and duration, describing radial motion of blob-like structures. In the case of an exponential pulse shape and exponentially distributed pulse amplitudes, predictions are given for the lowest order moments, probability density function, auto-correlation function, level crossings, and average times for periods spent above and below a given threshold level. Also, the mean squared errors on estimators of sample mean and variance for realizations of the process by finite time series are obtained. These results are discussed in the context of single-point measurements of fluctuations in the scrape-off layer, broad density profiles, and implications for plasma–wall interactions due to the transient transport events in fusion grade plasmas. The results may also have wide applications for modelling fluctuations in other magnetized plasmas such as basic laboratory experiments and ionospheric irregularities.
- OSTI ID:
- 22600084
- Journal Information:
- Physics of Plasmas, Vol. 23, Issue 5; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Comparison between mirror Langmuir probe and gas-puff imaging measurements of intermittent fluctuations in the Alcator C-Mod scrape-off layer
Convergence of statistical moments of particle density time series in scrape-off layer plasmas
Related Subjects
AMPLITUDES
CORRELATION FUNCTIONS
CORRELATIONS
DISTRIBUTION
ERRORS
FLUCTUATIONS
FORECASTING
PLASMA DENSITY
PLASMA SCRAPE-OFF LAYER
PLASMA SIMULATION
PROBABILITY
PROBABILITY DENSITY FUNCTIONS
PULSE SHAPERS
PULSES
STOCHASTIC PROCESSES
TRANSPORT THEORY
WALL EFFECTS
WALLS