Beam Generation and Transport in THz Tubes

We present results of 3D simulations of circular and non-circular electron beams for vacuum electronic devices operating at frequencies to 650 GHz. Magnetic and electrostatic lenses and periodic permanent magnet structures will be considered. A typical beam cross section is 150 times 30 microns with 6-8 mA at 10 - 50 keV. Comparison of the calculation with experimental results, as available, will be given.