Observation of trapped-electron-mode microturbulence in reversed field pinch plasmas
| Autor: | Weixing Ding, J. S. Sarff, J. Duff, D. L. Brower, B. E. Chapman, M.J. Pueschel, Z. R. Williams, Paul Terry |
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| Rok vydání: | 2018 |
| Předmět: | |
| Zdroj: | Physics of Plasmas. 25:010701 |
| ISSN: | 1089-7674 1070-664X |
| DOI: | 10.1063/1.5010198 |
| Popis: | Density fluctuations in the large-density-gradient region of improved confinement Madison Symmetric Torus reversed field pinch (RFP) plasmas exhibit multiple features that are characteristic of the trapped-electron mode (TEM). Core transport in conventional RFP plasmas is governed by magnetic stochasticity stemming from multiple long-wavelength tearing modes. Using inductive current profile control, these tearing modes are reduced, and global confinement is increased to that expected for comparable tokamak plasmas. Under these conditions, new short-wavelength fluctuations distinct from global tearing modes appear in the spectrum at a frequency of f ∼ 50 kHz, which have normalized perpendicular wavenumbers k⊥ρs≲0.2 and propagate in the electron diamagnetic drift direction. They exhibit a critical-gradient threshold, and the fluctuation amplitude increases with the local electron density gradient. These characteristics are consistent with predictions from gyrokinetic analysis using the Gene code, including ... |
| Databáze: | OpenAIRE |
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