Gyrokinetic ion/fluid electron simulation of nonlinear evolution of multiple Reverse Shear Alfven Eigenmodes

We report simulation of simultaneous excitation of multiple Reverse Shear Alfven eigenmodes in DIII-D plasmas (discharge #142111), using the gyrokinetic ion/fluid electron hybrid model of GEM. Thermal ions and beam ions are gyrokinetic, electrons are fluid with finite-mass correction in the Ohm's law. The vorticity equation is solved instead of the quasi-neutrality condition. This improves numerical stability. We extend previous single-n nonlinear simulation \footnote{Chen et. al. Phys. Plasmas {\bf 20}, 012109 (2013)} to simultaneous excitation of toroidal modes with $n=0$ and $2