Using the separation method, absolute parametric instability (API) of electrostatic waves in a magnetized pumped warm plasma is investigated. In this case the effect of static strong magnetic field is considered. The problem of strong magnetic field is solved in two-dimensional (2D) nonuniform plane plasma. Equations which describe the spatial part of the electric potential are obtained. Also, the growth rates and conditions of the parametric instability for periodic and aperiodic cases are obtained. It is found that the spatial nonuniformity of the plasma exerts a stabilizing effect on the API. It is shown that the growth rates of periodic and aperiodic API in warm plasma are less when compared to that in cold plasma.

The Weibel instability (WI) of relativistic electron beam (REB) penetrating an infinite collisional plasma was studied in the following models: (i) REB model, where the total equilibrium distribution function $f_{0} (\bar{p})$ is approximated by nonrelativistic back-ground electron and REB distribution functions and (ii) relativistic monoenergetic beam (RMB) model, where $f_{0}(\bar{p})$ is approximated by nonrelativistic background electrons and RMB distribution functions.

The dispersion equation including the effect of collision for a purely transverse mode describing each model was derived and solved analytically to obtain growth rates and conditions of excitation of the WI in the limit of high plasma temperature.

The purpose of this paper is to determine the effect of collision within the plasma on the growth rate of the WI for the two models. It was proved that the plasma collision frequency reduces the growth rate of WI at high plasma temperature. That is to say, collisions are inversely proportional to the growth rate. This leads to the important result: WI can be stabilized by increasing the plasma temperature.

Comparing the growth rate of WI in the two models (RMB and REB models), we came to the conclusion that growth rate of WI is more in the second case (REB case).