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Title: Universality of Poisson-driven plasma fluctuations in the Alcator C-Mod scrape-off layer

Abstract

Large-amplitude, intermittent fluctuations are ubiquitous in the boundary region of magnetically confined plasmas and lead to detrimental plasma-wall interactions in next-generation, high duty cycle fusion power experiments. Using gas puff imaging data time series from the scrape-off layer in the Alcator C-Mod device, it is demonstrated in this work that the large-amplitude fluctuations can be described as a super-position of pulses with a fixed shape and a constant duration. By applying a new deconvolution algorithm on the data time series with a two-sided exponential pulse function, the arrival times and amplitudes of the pulses can be estimated, and the measurement time series can be reconstructed with high accuracy. The pulse amplitudes are shown to follow an exponential distribution. The waiting times between pulses are uncorrelated, their distribution has an exponential tail, and the number of arrivals is a linear function of time. This demonstrates that pulse arrivals follow a homogeneous Poisson process. Identical statistical properties apply to both ohmic and high confinement mode plasmas, clearly demonstrating the universality of the fluctuation statistics in the boundary region of Alcator C-Mod.

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1];  [2]; ORCiD logo [2]
  1. UiT The Arctic Univ. of Norway, Tromsø (Norway)
  2. MIT Plasma Science and Fusion Center, Cambridge, MA (United States)
Publication Date:
Research Org.:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Sponsoring Org.:
Research Council of Norway; USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1609300
Grant/Contract Number:  
FC02-99ER54512; 240510/ F20
Resource Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 25; Journal Issue: 12; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; Physics

Citation Formats

Theodorsen, A., Garcia, O. E., Kube, R., LaBombard, B., and Terry, J. L. Universality of Poisson-driven plasma fluctuations in the Alcator C-Mod scrape-off layer. United States: N. p., 2018. Web. doi:10.1063/1.5064744.
Theodorsen, A., Garcia, O. E., Kube, R., LaBombard, B., & Terry, J. L. Universality of Poisson-driven plasma fluctuations in the Alcator C-Mod scrape-off layer. United States. https://doi.org/10.1063/1.5064744
Theodorsen, A., Garcia, O. E., Kube, R., LaBombard, B., and Terry, J. L. Tue . "Universality of Poisson-driven plasma fluctuations in the Alcator C-Mod scrape-off layer". United States. https://doi.org/10.1063/1.5064744. https://www.osti.gov/servlets/purl/1609300.
@article{osti_1609300,
title = {Universality of Poisson-driven plasma fluctuations in the Alcator C-Mod scrape-off layer},
author = {Theodorsen, A. and Garcia, O. E. and Kube, R. and LaBombard, B. and Terry, J. L.},
abstractNote = {Large-amplitude, intermittent fluctuations are ubiquitous in the boundary region of magnetically confined plasmas and lead to detrimental plasma-wall interactions in next-generation, high duty cycle fusion power experiments. Using gas puff imaging data time series from the scrape-off layer in the Alcator C-Mod device, it is demonstrated in this work that the large-amplitude fluctuations can be described as a super-position of pulses with a fixed shape and a constant duration. By applying a new deconvolution algorithm on the data time series with a two-sided exponential pulse function, the arrival times and amplitudes of the pulses can be estimated, and the measurement time series can be reconstructed with high accuracy. The pulse amplitudes are shown to follow an exponential distribution. The waiting times between pulses are uncorrelated, their distribution has an exponential tail, and the number of arrivals is a linear function of time. This demonstrates that pulse arrivals follow a homogeneous Poisson process. Identical statistical properties apply to both ohmic and high confinement mode plasmas, clearly demonstrating the universality of the fluctuation statistics in the boundary region of Alcator C-Mod.},
doi = {10.1063/1.5064744},
journal = {Physics of Plasmas},
number = 12,
volume = 25,
place = {United States},
year = {Tue Dec 18 00:00:00 EST 2018},
month = {Tue Dec 18 00:00:00 EST 2018}
}

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Cited by: 9 works
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Works referencing / citing this record:

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