Extended bounce-kinetic model for trapped electron mode turbulence

The bounce-kinetic model based on the modern nonlinear bounce-kinetic theory [Fong and Hahm, Phys. Plasmas 6, 188 (1999)] has been developed and used for simulations previously. This work reports on an extension of the bounce-kinetic model including more accurate treatment of barely trapped particles and its implementation in the Gyro-Kinetic Plasma Simulation Program gyrokinetic code [Kwon et al., Comp. Phys. Commun. 215, 81 (2017)]. This leads to more accurate gyrokinetic simulations of the collisionless trapped electron mode at low magnetic shear.