Nonlinear kinetic Alfvén waves in bi-ion plasmas

This paper investigates the features of the nonlinear kinetic Alfvén waves (KAWs) in a magnetized bi-ion plasma. In such a plasma model, a general Sagdeev equation can be obtained for different ranges of the plasma parameter α ≡ β/2Q (where β is the pressure ratio of the thermal to magnetic and Q is the mass ratio of electrons to protons). The analytical results show that the nonlinear dispersion curve of the KAWs is divided into two branches, and the wave phase speed decreases with more heavy ions. The numerical results indicate that both hump and dip density solitons, whose width and amplitude are affected by heavy ions, can possibly coexist in such bi-ion plasmas.