Gyrofluid investigation of electron FLR effects on reconnection

Camille Granier

The linear and nonlinear evolution of the tearing instability in a collisionless plasma with a strong guide field is analysed on the basis of a two-field Hamiltonian gyrofluid model. This model, based on a quasi-static closure, is a gyrofluid extension of previous studies based on the β -> 0 limit (Porcelli F., Borgogno D., Califano F., Grasso D., Ottaviani M., Pegoraro F., Plasma Phys. Control. Fusion (2002)), where β is the ratio between the electron pressure and the magnetic pressure. The finite β value, which can be relevant for collisionless plasmas such as the solar wind, involves a magnetic perturbation along the guide field direction and electron finite Larmor radius effects. Gyrofluid models provide an effective tool, complementary to kinetic models, for studying such contributions. In this study, magnetic reconnection can be driven by electron inertia and by FLR effects. The growth rate of the tearing instability is evaluated considering a fixed mass ratio, $m_e/m_i=0.01$.