Convective excitation of quasistatic waves in an inhomogeneous anisothermic plasma. II

Nonlinear effects stabilizing the convective instabilities excited in an anisothermic plasma (Tsub(e)>>Tsub(i)) at the plasma boundary (a< or approximately Vsub(s)/ωsub(Bi)) are discussed. Waves having in the linear theory (Part I) the highest growth rates (γ>>ωsub(Bi)) saturate at first. Being excited by a small part of slow plasma electrons (vsub(z)<<vsub(Te)) only, they saturate at a relatively low level. Further, surface waves with lower frequencies and higher phase velocities (vsub(ph)=ω/ksub(z)) become dominant and a broadening of the plasma boundary occurs. For their saturation nonlinear interaction is more important than the quasilinear effects. During the time interval of several ωsub(Bi)sup(-1) the longest surface waves with ksub(y) approximately ωsub(Bi)/Vsub(s), γ approximately ω approximately ωsub(Bi) approximately ksub(y)Vsub(s) and vsub(ph) approximately vsub(Te) saturate at the absolutely highest level. The plasma boundary broadens in the meanwhile up to a approximately Vsub(s)/ωsub(Bi). The wave energy is comparable to the total energy connected with the longitudinal motion of the initially thermal electrons inside this boundary layer. The wave amplitude is large enough to trap the initially cold ions belonging to this layer and 'heat' them up to energies comparable to those of the electron component. The heating process again occurs within several ωsub(Bi)sup(-1) and the Larmor radius of the ions is then comparable to Vsub(s)/ωsub(Bi). Further evolution of the system is governed by the unstable local perturbations. (author)