PARTICLE SIMULATIONS OF DIVERGENT AND CONVERGENT RADIAL ELECTRON FLOWS IN CYLINDRICAL PIERCE DIODES

A special class of Pierce diodes, that consists of a pair of grounded coaxial cylindrical electrodes, with electrons streaming radially betw een them, is studied. The full set of roots of the dispersion relation of the Pierce instability is obtained by solving the dispersion relat ion numerically. The nonlinear behaviour of the system is then investi gated using particle simulation. It is shown that the behaviour of cyl indrical systems depends on two nondimensional parameters. Linear and nonlinear properties are different for convergent and divergent config urations. Several remarkable differences between cylindrical and plana r Pierce diodes are reported. (C) 1997 American Institute of Physics.