Kinetic heat pulse propagation in the tokamak scrape-off layer*

In order to predict the heat and particle fluxes impinging on the target plate of a tokamak divertor, the transient behavior of a plasma heat pulse that travels along a magnetic flux tube is studied using the 4D long wavelength gyrokinetic COGENT code.  Both kinetic electrons and kinetic ions are used along with gyrokinetic sheath boundary conditions [1]. Results are compared to heat pulse propagation test problems [2-3] that have been used to compare physics models and numerical algorithms.  Simulations show that the particle distribution functions can become non-Maxwellian in the collisionless limit.  Comparison to fluid models will be used to assess under which conditions kinetic effects become important.

[1] E. L. Shi, G. W. Hammett, T. Stoltzfus-Dueck, and A. Hakim, J. Plasma Phys. 83, 905830304 (2017).

[2] E. L. Shi, A. H. Hakim, and G. Hammett, Phys. Plasmas 22, 022504 (2015).

[3] E. Havlickova, W. Fundamenski, D. Tskhakaya, et al., Plasma Phys. Control. Fusion 54, 045002 (2012).