Damping Effects on Parametric Decays of Alfvén Waves

It is shown that damping effects can destabilize regions that are stable under non-dissipative fluid theory. Damping effects on the ion-acoustic modes are simulated by a collisional-like term in the longitudinal component of the fluid equations. It is shown that when there is only a beat wave instability, damping effects can destabilize modulational and decay-type instabilities. These results are in agreement with hybrid kinetic-fluid approaches and hybrid simulation codes. This revised version was published online in July 2006 with corrections to the Cover Date.