Microtearing modes can play a crucial role in electron heat transport in tokamak plasmas, affecting both energy confinement and overall performance. This study investigates microtearing modes (MTM) stability and turbulence in a JET pedestal through gyrokinetic simulations using the Gene code, complemented by a reduced eigenvalue model. The focus is on how MTM properties depend on key plasma parameters, including collisionality and plasma beta β—the ratio of plasma pressure to magnetic pressure—the normalized toroidal wavenumber kyρs, where ρs denotes the ion sound gyroradius (typically a few millimeters in edge plasmas) and isotope mass. Collisionality enhances MT growth rates, while increasing β leads to a shift from MTMs to kinetic-ballooning modes, typically for kyρs, where ρs ≲ 0.2. A purely collisionless branch of MTMs persists at low kyρs, where ρs with distinctive properties including non-negligible particle flux and ion thermal transport. Isotope mass scans reveal modest reduction of MTM growth rates as ion mass decreases. Nonlinear simulations produce experimentally relevant transport levels. Numerical experiments turning off zonal flows and fields identify the critical role of zonal flows and zonal fields in regulating MTM turbulence. Their removal leads to a significant increase in electron heat flux. These findings provide new insight into MTM-driven transport and its impact on tokamak confinement and lay a foundation for reduced modeling and predictive capabilities.
Hamed, Myriam, et al. "Microtearing stability and turbulence in the pedestal: Linear gyrokinetics, reduced models, and nonlinear turbulent transport." Physics of Plasmas, vol. 32, no. 9, Sep. 2025. https://doi.org/10.1063/5.0274287
Hamed, Myriam, Hatch, D. R., Pueschel, M. J., & Jitsuk, T. (2025). Microtearing stability and turbulence in the pedestal: Linear gyrokinetics, reduced models, and nonlinear turbulent transport. Physics of Plasmas, 32(9). https://doi.org/10.1063/5.0274287
Hamed, Myriam, Hatch, D. R., Pueschel, M. J., et al., "Microtearing stability and turbulence in the pedestal: Linear gyrokinetics, reduced models, and nonlinear turbulent transport," Physics of Plasmas 32, no. 9 (2025), https://doi.org/10.1063/5.0274287
@article{osti_2997739,
author = {Hamed, Myriam and Hatch, D. R. and Pueschel, M. J. and Jitsuk, T.},
title = {Microtearing stability and turbulence in the pedestal: Linear gyrokinetics, reduced models, and nonlinear turbulent transport},
annote = {Microtearing modes can play a crucial role in electron heat transport in tokamak plasmas, affecting both energy confinement and overall performance. This study investigates microtearing modes (MTM) stability and turbulence in a JET pedestal through gyrokinetic simulations using the Gene code, complemented by a reduced eigenvalue model. The focus is on how MTM properties depend on key plasma parameters, including collisionality and plasma beta β—the ratio of plasma pressure to magnetic pressure—the normalized toroidal wavenumber kyρs, where ρs denotes the ion sound gyroradius (typically a few millimeters in edge plasmas) and isotope mass. Collisionality enhances MT growth rates, while increasing β leads to a shift from MTMs to kinetic-ballooning modes, typically for kyρs, where ρs ≲ 0.2. A purely collisionless branch of MTMs persists at low kyρs, where ρs with distinctive properties including non-negligible particle flux and ion thermal transport. Isotope mass scans reveal modest reduction of MTM growth rates as ion mass decreases. Nonlinear simulations produce experimentally relevant transport levels. Numerical experiments turning off zonal flows and fields identify the critical role of zonal flows and zonal fields in regulating MTM turbulence. Their removal leads to a significant increase in electron heat flux. These findings provide new insight into MTM-driven transport and its impact on tokamak confinement and lay a foundation for reduced modeling and predictive capabilities.},
doi = {10.1063/5.0274287},
url = {https://www.osti.gov/biblio/2997739},
journal = {Physics of Plasmas},
issn = {ISSN 1089-7674},
number = {9},
volume = {32},
place = {United States},
publisher = {AIP Publishing},
year = {2025},
month = {09}}
Field, A. R.; Chapman-Oplopoiou, B.; Connor, J. W.
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol. 381, Issue 2242https://doi.org/10.1098/rsta.2021.0228