Soroka S. Deformation of the inhomogeneous plasma concentration profile on the interaction modulated electron beam

Interaction of the wide modulated electron beam with the inhomogeneous plasma in 1D geometry was studied using the computer simulation via PIC method. The last stage of the process depends strongly on the relation of electron and ion temperatures. In the isothermal plasma the cavity is gradually transformed into the density step. For large current densities this step moves into the dense plasma with the velocity of the order of ion thermal velocity. In plasma with hot electrons ionacoustic pulses propagate from LPRR to supercritical and subcritical plasma. New bursts of HF field are excited at the local density maxima of subcritical plasma producing new ion-acoustic pulses. Consequently at the late stage of the beam-plasma interaction ion-acoustic pulses appear in the large spatial area near LPRR. Similar behavior is demonstrated by the inhomogeneous plasma in the homogeneous HF pumping electric field.