numerical simulation.

The influence of additive homogeneous isotropic field of Gauss fluctuations of dynamical variables of Gierer–Meinhardt model to formation of dissipative structures in soft mode regime was investigated. The system of equations for description of undamped modes interaction was received. It was shown that fluctuations of dynamical variables are widening the instability region. The numerical simulation of considered model with different boundary condition was performed.

The results of preliminary 3D fully electromagnetic simulation of microwave generator with virtual cathode and external feedback loop (virtode) are discussed in this paper. The feedback is realized by the velocity modulation of electron beam in the accelerating gap of electron gun with the electromagnetic signal taken with output cavity placed in the virtual cathode area.