Investigating a Lower Limit for the Magnetic Field in a TWT

Stable operation is one of the challenging difficulties of a traveling wave tube when it comes to designing. Mismatches at the couplers, spreading of the beam more than necessary due to space-charge forces etc. may lead to self-excitations of the tube. The spreading of the beam may also lead to backward wave oscillations[1].For this reason the beam focusing is an important matter on TWT operation and strong magnetic fields are required for the confinement of the beam.In this study a lower limit for the magnetic field will be investigated for given beam parameters. CST Studio Suite will be used for modelling and simulations of a Ku band TWT [2].