Evolution of an electron beam with azimuthal density non-uniformity in a cylindrical beam tunnel

We present the results on the deformation of the cross-section of an electron beam in a cylindrical beam tunnel with ∂/∂z=0 and homogeneous magnetic field, due to azimuthally non-uniform current density distribution. For the numerical simulation, the code ARIADNE has been used. In addition, a simple theoretical model has been found adequate to interpret the numerical results, qualitatively and quantitatively. It has been found, that the azimuthal non-uniformity causes effects clearly associated with E×B drifts, but in absolute terms these effects are too small to affect the performance of a gyrotron.