Nonlinear competition between the whistler and Alfven fire hoses

We examine a competition between the whistler and Alfven fire hoses driven by bi-Maxwellian protons with T-p// > T-p perpendicular to, where T-p// and T-p perpendicular to are proton temperatures, parallel and perpendicular t o the background magnetic field, respectively. We extend the work of Hellin ger and Matsumoto [2000] using a two-dimensional hybrid simulation that inc ludes both the instabilities. In the simulation the whistler fire hose init ially dominates and saturates in a quasi-linear manner. The Alfven fire hos e is not strongly affected by the presence of the whistler fire hose and gr ows even when the former is saturated. However, as the Alfven fire hose gro ws and saturates via a conversion to Alfven waves that heat the protons, th e waves driven by the whistler fire hose get strongly damped and disappear. The Alfven waves damp as well, so that at the end of the simulation the wa ve activity is low. The strong decay of the generated waves translates to a n important decrease of the proton temperature anisotropy.