Electromagnetic Electron Density Fluctuations and β Parameter Fluctuations at the Edge of the JET Tokamak: Kinetic Effects of Pressure Anisotropy with Bi-Maxwellian Distribution

Said Mouigni Abdallah^1, , Ibrahima Gueye Faye¹, Mamadou Coulibaly¹, Louis Gomis¹, Clément Diatta¹ and Amadou Diao²

¹Laboratory of Plasma Physics and Interdisciplinary Research (LPPRI), Department of Physics, Faculty of Science and Technology, Cheikh Anta Diop University of Dakar (UCAD)

²Laboratory of Solar Energy, Materials and Systems, Department of Physics, Faculty of Science and Technology, Cheikh Anta Diop University of Dakar (UCAD)

Cite this paper:
Said Mouigni Abdallah, Ibrahima Gueye Faye, Mamadou Coulibaly, Louis Gomis, Clément Diatta and Amadou Diao. Electromagnetic Electron Density Fluctuations and β Parameter Fluctuations at the Edge of the JET Tokamak: Kinetic Effects of Pressure Anisotropy with Bi-Maxwellian Distribution. International Journal of Physics. 2026; 14(4):77-85. doi: 10.12691/ijp-14-4-1

Abstract

This work examines the effect of electron pressure anisotropy on electromagnetic density fluctuations and the MHD stability parameter at the JET tokamak edge in the kinetic limit . Using a bi‑Maxwellian equilibrium and solving the linearized gyrokinetic Vlasov equation, we derive via the Fried‑Conte function. Accounting for density and magnetic field fluctuations yields. A critical anisotropy threshold is found. For (cases), the response is Landau‑damped () and ranges from 0.048% (weak turbulence,) to 4.370% (average turbulence,), staying below the 5% MHD ballooning threshold. The case gives the lowest fluctuations. For , becomes negative, signalling a kinetic mirror instability. In average turbulence, , exceeding the MHD threshold and indicating a pre‑ELM state. Comparison with Li‑BES measurements (Réfy et al. 2018) confirms moderate‑anisotropy cases, while extreme firehose () and mirror () match pre‑ELM triggering under NBI and ICRH heating, respectively.

Keywords:
Electron pressure anisotropy electromagnetic density fluctuations JET tokamak edge Bi-Maxwellian distribution Vlasov equation

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