Squeezed state of high-current electron beam

The results of the computer simulation of an electron beam propagating serially through two coaxial tubes with different radii are presented. It is shown that the virtual cathode in this system may be located in one of two positions depending on the injection current, variation of which yields fast movements of the potential barrier. Under certain conditions, a part of the beam may be in its squeezed state, forming, therefore, a cloud of a dense warm plasma. The qualitative analytical theory based on the consideration of the energy and momentum balance is also discussed.