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Kenmochi N, Ida K, Tokuzawa T, Yasuhara R, Funaba H, Uehara H, Den Hartog DJ, Yamada I, Yoshinuma M, Takemura Y, Igami H. Preceding propagation of turbulence pulses at avalanche events in a magnetically confined plasma. Sci Rep 2022; 12:6979. [PMID: 35577787 PMCID: PMC9110360 DOI: 10.1038/s41598-022-10499-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 04/11/2022] [Indexed: 11/09/2022] Open
Abstract
The preceding propagation of turbulence pulses has been observed for the first time in heat avalanche events during the collapse of the electron internal transport barrier (e-ITB) in the Large Helical Device. The turbulence and heat pulses are generated near the foot of the e-ITB and propagate to the peripheral region within a much shorter time than the diffusion timescale. The propagation speed of the turbulence pulse is approximately 10 km/s, which is faster than that of the heat pulse propagating at a speed of 1.5 km/s. The heat pulse propagates at approximately the same speed as that in the theoretical prediction, whereas the turbulence pulse propagates one order of magnitude faster than that in the prediction, thereby providing important insights into the physics of non-local transport.
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Affiliation(s)
- N Kenmochi
- National Institute for Fusion Science, Toki, Gifu, 509-5292, Japan.
| | - K Ida
- National Institute for Fusion Science, Toki, Gifu, 509-5292, Japan
- The Graduate University for Advanced Studies, SOKENDAI, Toki, Gifu, 509-5292, Japan
| | - T Tokuzawa
- National Institute for Fusion Science, Toki, Gifu, 509-5292, Japan
- The Graduate University for Advanced Studies, SOKENDAI, Toki, Gifu, 509-5292, Japan
| | - R Yasuhara
- National Institute for Fusion Science, Toki, Gifu, 509-5292, Japan
| | - H Funaba
- National Institute for Fusion Science, Toki, Gifu, 509-5292, Japan
| | - H Uehara
- National Institute for Fusion Science, Toki, Gifu, 509-5292, Japan
- The Graduate University for Advanced Studies, SOKENDAI, Toki, Gifu, 509-5292, Japan
| | - D J Den Hartog
- Wisconsin Plasma Physics Laboratory, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - I Yamada
- National Institute for Fusion Science, Toki, Gifu, 509-5292, Japan
| | - M Yoshinuma
- National Institute for Fusion Science, Toki, Gifu, 509-5292, Japan
- The Graduate University for Advanced Studies, SOKENDAI, Toki, Gifu, 509-5292, Japan
| | - Y Takemura
- National Institute for Fusion Science, Toki, Gifu, 509-5292, Japan
- The Graduate University for Advanced Studies, SOKENDAI, Toki, Gifu, 509-5292, Japan
| | - H Igami
- National Institute for Fusion Science, Toki, Gifu, 509-5292, Japan
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Hammond KC, Laggner FM, Diallo A, Doskoczynski S, Freeman C, Funaba H, Gates DA, Rozenblat R, Tchilinguirian G, Xing Z, Yamada I, Yasuhara R, Zimmer G, Kolemen E. Initial operation and data processing on a system for real-time evaluation of Thomson scattering signals on the Large Helical Device. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:063523. [PMID: 34243539 DOI: 10.1063/5.0041507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 05/22/2021] [Indexed: 06/13/2023]
Abstract
A scalable system for real-time analysis of electron temperature and density based on signals from the Thomson scattering diagnostic, initially developed for and installed on the NSTX-U experiment, was recently adapted for the Large Helical Device and operated for the first time during plasma discharges. During its initial operation run, it routinely recorded and processed signals for four spatial points at the laser repetition rate of 30 Hz, well within the system's rated capability for 60 Hz. We present examples of data collected from this initial run and describe subsequent adaptations to the analysis code to improve the fidelity of the temperature calculations.
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Affiliation(s)
- K C Hammond
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - F M Laggner
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - A Diallo
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - S Doskoczynski
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - C Freeman
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - H Funaba
- National Institute for Fusion Science, Toki 509-5292, Japan
| | - D A Gates
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - R Rozenblat
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - G Tchilinguirian
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - Z Xing
- Princeton University, Princeton, New Jersey 08544, USA
| | - I Yamada
- National Institute for Fusion Science, Toki 509-5292, Japan
| | - R Yasuhara
- National Institute for Fusion Science, Toki 509-5292, Japan
| | - G Zimmer
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - E Kolemen
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
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Ii Tsujimura T, Mizuno Y, Yanai R, Tokuzawa T, Ito Y, Nishiura M, Kubo S, Shimozuma T, Yoshimura Y, Igami H, Takahashi H, Tanaka K, Yoshinuma M, Ohshima S. Real-time control of the deposition location of ECRH in the LHD. FUSION ENGINEERING AND DESIGN 2020. [DOI: 10.1016/j.fusengdes.2020.111480] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Laggner FM, Diallo A, LeBlanc BP, Rozenblat R, Tchilinguirian G, Kolemen E. A scalable real-time framework for Thomson scattering analysis: Application to NSTX-U. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2019; 90:043501. [PMID: 31042978 DOI: 10.1063/1.5088248] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 03/21/2019] [Indexed: 06/09/2023]
Abstract
A detailed description of a prototype setup for real-time (RT) Thomson scattering (TS) analysis is presented and implemented in the multi-point Thomson scattering (MPTS) diagnostic system at the National Spherical Torus Experiment Upgrade (NSTX-U). The data acquisition hardware was upgraded with RT capable electronics (RT-analog digital converters and a RT server) that allow for fast digitization of the laser pulse signal of eight radial MPTS channels. In addition, a new TS spectrum analysis software for a rapid calculation of electron temperature (Te) and electron density (ne) was developed. Testing of the RT hardware and data analysis software was successfully completed and benchmarked against the standard, post-shot evaluation. Timing tests were performed showing that the end-to-end processing time was reproducibly below 17 ms for the duration of at least 5 s, meeting a 60 Hz deadline by the laser pulse repetition rate over the length of a NSTX-U discharge. The presented RT framework is designed to be scalable in system size, i.e., incorporation of additional radial channels by solely adding additional RT capable hardware. Furthermore, it is scalable in its operation duration and was continuously running for up to 30 min, making it an attractive solution for machines with long discharges such as advanced, non-inductive tokamaks or stellarators.
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Affiliation(s)
- F M Laggner
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - A Diallo
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - B P LeBlanc
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - R Rozenblat
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - G Tchilinguirian
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - E Kolemen
- Princeton University, Princeton, New Jersey 08544, USA
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