Non-linear theory of hydromagnetic waves in a high β plasma

A non-linear integro-differential equation is derived, governing the space time evolution of non-linear hydromagnetic waves in a finite β collisionless plasma. The theory is done for quasi-perpendicular propagation, for wave frequencies above ion cyclotron frequency, and wavelengths smaller than ion Larmor radius. In the low β limit, the derived equation reduces to a Korteweg de Vries equation.