Phase mixing of Alfvén pulses and wavetrains propagating in coronal holes

The propagation of Alfvén pulses into an inhomogeneous model of a solar coronal hole is investigated. The algebraic damping of single and bi–polar pulses remains for the leading and trailing pulses as the number of pulses is increased but the decay of the internal pulses returns to the exponential damping of an infinite wavetrain when three pulses or more are present. Thus, wavetrains with most of their energy residing in internal oscillations will be dominated by efficient exponential damping. In contrast, short wavetrains with most of their energy in the leading and trailing pulses will suffer less efficient algebraic damping. The implications of both the damping of these disturbances to the heating of coronal holes and the nonlinear wave pressure to the acceleration of the solar wind are discussed.