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Nishizawa T, Griener M, Dux R, Grenfell G, Wendler D, Kado S, Manz P, Cavedon M. Linearized spectrum correlation analysis for thermal helium beam diagnostics. Rev Sci Instrum 2021; 92:103501. [PMID: 34717377 DOI: 10.1063/5.0062436] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 09/10/2021] [Indexed: 06/13/2023]
Abstract
We introduce a new correlation analysis technique for thermal helium beam (THB) diagnostics. Instead of directly evaluating line ratios from fluctuating time series, we apply arithmetic operations to all available He I lines and construct time series with desired dependencies on the plasma parameters. By cross-correlating those quantities and by evaluating ensemble averages, uncorrelated noise contributions can be removed. Through the synthetic data analysis, we demonstrate that the proposed analysis technique is capable of providing the power spectral densities of meaningful plasma parameters, such as the electron density and the electron temperature, even under low-photon-count conditions. In addition, we have applied this analysis technique to the experimental THB data obtained at the ASDEX Upgrade tokamak and successfully resolved the electron density and temperature fluctuations up to 90 kHz in a reactor relevant high power scenario.
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Affiliation(s)
- T Nishizawa
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany
| | - M Griener
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany
| | - R Dux
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany
| | - G Grenfell
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany
| | - D Wendler
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany
| | - S Kado
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0 011, Japan
| | - P Manz
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany
| | - M Cavedon
- Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany
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Liu L, Yu D, Chen W, He X, He X, Wei Y, Li D, Yang Z, Gao J, Li Y, Zhang K, Zhou Y, Yan L, Shi Z, Liu Y, Yang Q. Development of a passive visible spectroscopic diagnostic on HL-2A tokamak. Fusion Engineering and Design 2019. [DOI: 10.1016/j.fusengdes.2019.03.095] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Nishizawa T, Almagri AF, Anderson JK, Goodman W, Pueschel MJ, Nornberg MD, Ohshima S, Sarff JS, Terry PW, Williams ZR. Direct Measurement of a Toroidally Directed Zonal Flow in a Toroidal Plasma. Phys Rev Lett 2019; 122:105001. [PMID: 30932630 DOI: 10.1103/physrevlett.122.105001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Revised: 02/16/2019] [Indexed: 06/09/2023]
Abstract
Zonal flow appears in toroidal, magnetically confined plasmas as part of the self-regulated interaction of turbulence and transport processes. For toroidal plasmas having a strong toroidal magnetic field, the zonal flow is predominately poloidally directed. This Letter reports the first observation of a zonal flow that is toroidally directed. The measurements are made just inside the last closed flux surface of reversed field pinch plasmas that have a dominant poloidal magnetic field. A limit cycle oscillation between the strength of the zonal flow and the amplitude of plasma potential fluctuations is observed, which provides evidence for the self-regulation characteristic of drift-wave-type plasma turbulence. The measurements help advance understanding and gyrokinetic modeling of toroidal plasmas in the pursuit of fusion energy.
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Affiliation(s)
- T Nishizawa
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - A F Almagri
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - J K Anderson
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - W Goodman
- Electrical Engineering Department, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - M J Pueschel
- Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712, USA
| | - M D Nornberg
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - S Ohshima
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - J S Sarff
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - P W Terry
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Z R Williams
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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