Interaction of magnetostatic and electrostatic convective cells

Abstract
We show that in the absence of magnetic shear the convective-cell modes in a magnetized plasma are strongly coupled. A three-wave decay instability can occur among two magnetostatic and one electrostatic zero-frequency modes. It is found that here cascading of energy is only in the direction of small wave numbers in the magnetostatic spectrum. Our results are compared with other cascading processes. The role of magnetic shear is also discussed.