Effect of source and sink on heat transport in the SOL

Froese, A.*; Takizuka, Tomonori; Yagi, Masatoshi

Electron heat transport parallel to magnetic field in the SOL is studied via fully kinetic simulations using the one-dimensional particle code PARASOL. The heat flux in fluid model is usually approximated with the Spitzer-Harm value in the collisional case, and the free-streaming value adjusted by a limiting factor in the collisionless case. While typically taken to be a constant 0.1, we survey the dependence of the limiting factor with respect to plasma parameters (collisionality, type of source and sink etc). It is found that the limiting factor is strongly affected by the collisionality, covering magnitude from 0.01 to 10. A high-energy tail plays an important role for this large variation. Langevin heating source maintains a Maxwellian electron energy distribution, and the limiting factor remains between 0.05 and 0.3. It is also found that the radiation loss is essential to increase the limiting factor.