PERIODIC FOCUSING MAGNETIC SYSTEM Russian patent published in 1995 - IPC

FIELD: electronic engineering. SUBSTANCE: periodic focusing magnetic system has magnetic blocks placed between pole shoes, each incorporating two magnets isolated by neutral shoes. Neutral and pole shoes are included in vacuum envelope of travelling-wave tube. Neutral shoes contribute to other than sinusoidal distribution of flux density in focusing system with high level of third harmonic. Each neutral shoe has two components mounted in a spaced relation with gap filled with nonferromagnetic material. EFFECT: improved reliability and service life of travelling-wave tube due to reduction of deceleration line working temperature and reduced quantity of vacuum-tight junctions of device envelope. 4 cl, 4 dwg