Pedestal magnetic turbulence measurements in ELMy H-mode DIII-D plasmas by Faraday-effect polarimetry
| Autor: | E. J. Strait, Jie Chen, Xiang Jian, Zheng Yan, Max Curie, T.H. Osborne, D. L. Brower, Weixing Ding, Swadesh M Mahajan, M. R. Halfmoon, David Hatch, Mike Kotschenreuther |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Physics of Plasmas. 28:022506 |
| ISSN: | 1089-7674 1070-664X |
| Popis: | Internal magnetic fluctuation measurements are utilized to identify turbulence associated with micro-tearing modes (MTM) in the DIII-D Edge-Localized-Mode (ELM)-y H-mode pedestal. Using a Faraday-effect polarimeter, magnetic turbulence (150–500 kHz) is directly observed with a typical line-averaged fluctuation amplitude of ∼0.8 G at peak frequency (250 kHz) and ∼15 G integrated over the spectrum from 150 to 500 kHz. Frequency, poloidal wavenumber, and propagation direction of the magnetic turbulence all serve to identify as MTM. Magnetic turbulence amplitude non-monotonically correlates with collision frequency, peaks off mid-plane, and correlates with electron temperature gradient evolution between ELMs, consistent with MTM features identified from theory and gyro-kinetic simulation. The magnetic turbulence growth correlates with confinement degradation in ELMy H-mode plasmas during a slow density ramp. These internal measurements provide unique constraints toward developing physics understanding and validating models of the H-mode pedestal for future devices. |
| Databáze: | OpenAIRE |
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