Gyrokinetic delta f simulation of the collisionless and semicollisional tearing mode instability

The evolution of collisionless and semicollisional tearing mode instabilities is studied using an electromagnetic gyrokinetic deltaf particle-in-cell simulation model. Drift-kinetic electrons are used. Linear eigenmode analysis is presented for the case of fixed ions and there is excellent agreement with simulation. A double peaked eigenmode structure is seen indicative of a positive Delta'. Nonlinear evolution of a magnetic island is studied and the results compare well with existing theory in terms of saturation level and electron bounce oscillations. Electron-ion collisions are included to study the sernicollisional regime. The algebraic growth stage is observed and compares favorably with theory. Nonlinear saturation following the algebraic stage is observed. (C) 2005 American Institute of Physics.