Magnetron injection gun for a multi-frequency gyrotron

A triode electron gun was developed to realize step-frequency tunability in a sub-THz gyrotron. Helical electron beams are formed with high-laminarity such that the velocity spreads are maintained at low levels in a wide operation range. The stable oscillations were experimentally confirmed at expected frequencies from 162 to 265 GHz with powers of the order of 1 kW.