New, improved analysis of correlation ECE data to accurately determine turbulent electron temperature spectra and magnitudes (invited)
Abstract
Turbulent electron temperature fluctuation measurement using a correlation electron cyclotron emission (CECE) radiometer has become an important diagnostic for studying energy transport in fusion plasmas, and its use is widespread in tokamaks (DIII-D, ASDEX Upgrade, Alcator C-Mod, Tore Supra, EAST, TCV, HL-2A, etc.). The CECE diagnostic typically performs correlation analysis between two closely spaced (within the turbulent correlation length) ECE channels that are dominated by uncorrelated thermal noise emission. This allows electron temperature fluctuations embedded in the thermal noise to be revealed and fluctuation level and spectra determined. We have demonstrated a new, improved CECE coherency-based analysis for calculating the temperature fluctuation frequency spectrum and level, which has been verified both numerically through the simulation of synthetic ECE radiometer data and through analysis of experimental data from the CECE system on DIII-D. The new formulation places coherency-based analysis on a firm foundational footing and corrects some currently published methodologies. This new method accurately accounts for bias error in the coherence function and correctly calculates noise levels for a fixed data record length. It provides excellent accuracy in determining temperature fluctuation level (e.g., <10% error) even for a small realization number in the ensemble average. The method also has a smallermore »
- Publication Date:
- Sponsoring Org.:
- USDOE
- OSTI Identifier:
- 1774712
- Grant/Contract Number:
- SC0019352; FG02-08ER54984; FC02-04ER54698
- Resource Type:
- Publisher's Accepted Manuscript
- Journal Name:
- Review of Scientific Instruments
- Additional Journal Information:
- Journal Name: Review of Scientific Instruments Journal Volume: 92 Journal Issue: 4; Journal ID: ISSN 0034-6748
- Publisher:
- American Institute of Physics
- Country of Publication:
- United States
- Language:
- English
Citation Formats
Wang, G., Rhodes, T. L., and Peebles, W. A. New, improved analysis of correlation ECE data to accurately determine turbulent electron temperature spectra and magnitudes (invited). United States: N. p., 2021.
Web. doi:10.1063/5.0041858.
Wang, G., Rhodes, T. L., & Peebles, W. A. New, improved analysis of correlation ECE data to accurately determine turbulent electron temperature spectra and magnitudes (invited). United States. https://doi.org/10.1063/5.0041858
Wang, G., Rhodes, T. L., and Peebles, W. A. Wed .
"New, improved analysis of correlation ECE data to accurately determine turbulent electron temperature spectra and magnitudes (invited)". United States. https://doi.org/10.1063/5.0041858.
@article{osti_1774712,
title = {New, improved analysis of correlation ECE data to accurately determine turbulent electron temperature spectra and magnitudes (invited)},
author = {Wang, G. and Rhodes, T. L. and Peebles, W. A.},
abstractNote = {Turbulent electron temperature fluctuation measurement using a correlation electron cyclotron emission (CECE) radiometer has become an important diagnostic for studying energy transport in fusion plasmas, and its use is widespread in tokamaks (DIII-D, ASDEX Upgrade, Alcator C-Mod, Tore Supra, EAST, TCV, HL-2A, etc.). The CECE diagnostic typically performs correlation analysis between two closely spaced (within the turbulent correlation length) ECE channels that are dominated by uncorrelated thermal noise emission. This allows electron temperature fluctuations embedded in the thermal noise to be revealed and fluctuation level and spectra determined. We have demonstrated a new, improved CECE coherency-based analysis for calculating the temperature fluctuation frequency spectrum and level, which has been verified both numerically through the simulation of synthetic ECE radiometer data and through analysis of experimental data from the CECE system on DIII-D. The new formulation places coherency-based analysis on a firm foundational footing and corrects some currently published methodologies. This new method accurately accounts for bias error in the coherence function and correctly calculates noise levels for a fixed data record length. It provides excellent accuracy in determining temperature fluctuation level (e.g., <10% error) even for a small realization number in the ensemble average. The method also has a smaller uncertainty (i.e., error bar) in the power spectrum when compared to the more standard cross-power method when evaluated at low coherency. Direct calculation of system noise level using correlation between randomized intermediate frequency signals is recommended.},
doi = {10.1063/5.0041858},
journal = {Review of Scientific Instruments},
number = 4,
volume = 92,
place = {United States},
year = {Wed Apr 07 00:00:00 EDT 2021},
month = {Wed Apr 07 00:00:00 EDT 2021}
}
Free Publicly Available Full Text
Publisher's Version of Record
https://doi.org/10.1063/5.0041858
https://doi.org/10.1063/5.0041858
Other availability
Search WorldCat to find libraries that may hold this journal
Save to My Library
You must Sign In or Create an Account in order to save documents to your library.
Works referenced in this record:
Measurement of electron temperature fluctuations using a tunable correlation electron cyclotron emission system on Alcator C-Mod
journal, November 2014
- Howard, N. T.; Sung, C.; White, A. E.
- Review of Scientific Instruments, Vol. 85, Issue 11
Measurement of turbulent electron temperature fluctuations on the ASDEX Upgrade tokamak using correlated electron cyclotron emission
journal, July 2016
- Freethy, S. J.; Conway, G. D.; Classen, I.
- Review of Scientific Instruments, Vol. 87, Issue 11
Design of a correlation electron cyclotron emission diagnostic for Alcator C-Mod
journal, October 2012
- Sung, C.; White, A. E.; Irby, J. H.
- Review of Scientific Instruments, Vol. 83, Issue 10
The design of a correlation electron cyclotron emission system on J-TEXT
journal, April 2015
- Yang, Z. J.; Xiao, Y.; Ma, X. D.
- Review of Scientific Instruments, Vol. 86, Issue 4
Correlation electron cyclotron emission diagnostic in TCV
journal, August 2017
- Fontana, M.; Porte, L.; Molina Cabrera, P.
- Review of Scientific Instruments, Vol. 88, Issue 8
A correlation electron cyclotron emission diagnostic and the importance of multifield fluctuation measurements for testing nonlinear gyrokinetic turbulence simulations
journal, October 2008
- White, A. E.; Schmitz, L.; Peebles, W. A.
- Review of Scientific Instruments, Vol. 79, Issue 10
A frequency tunable, eight-channel correlation ECE system for electron temperature turbulence measurements on the DIII-D tokamak
journal, August 2016
- Sung, C.; Peebles, W. A.; Wannberg, C.
- Review of Scientific Instruments, Vol. 87, Issue 11
Validation of gyrokinetic simulations with measurements of electron temperature fluctuations and density-temperature phase angles on ASDEX Upgrade
journal, May 2018
- Freethy, S. J.; Görler, T.; Creely, A. J.
- Physics of Plasmas, Vol. 25, Issue 5
An eight-channel correlation electron cyclotron emission diagnostic for turbulent electron temperature fluctuation measurement in HL-2A tokamak
journal, June 2019
- Fang, K. R.; Shi, Z. B.; Yang, Z. C.
- Review of Scientific Instruments, Vol. 90, Issue 6
50 Years of Electron Cyclotron Emission Research
journal, January 2009
- Costley, A. E.
- Fusion Science and Technology, Vol. 55, Issue 1
Correlation electron cyclotron emission diagnostic and improved calculation of turbulent temperature fluctuation levels on ASDEX Upgrade
journal, May 2018
- Creely, A. J.; Freethy, S. J.; Burke, W. M.
- Review of Scientific Instruments, Vol. 89, Issue 5