Design of Magnetic Focusing system for a Compact Ka band Helix TWT

In this paper we discuss the design of Magnetic focusing system (MFS) for a compact helix travelling wave tube (TWT) operating in Ka-band. Issues related to the design of the magnetic focusing system have been discussed in detail along with practical measurement results. The key design parameters considered for this TWT are: the cathode voltage is around 9.3kV, beam current is 200mA and total length of the tube not more than 6 inch with minimal weight.