Beam induced heating of ferrite magnets

Alerted by impedance measurements of ferrite kicker magnets and by apparent beam-induced pressure increases in the neighborhood of window frame kicker magnets, bench measurements of magnet heating have been done. They confirmed the necessity of interrupting the ferrite yoke. To reduce the impedance to the beam, a diamagnetic barrier in window frame ferrite magnets has proven to be very effective and it is shown that it is necessary for two other reasons, namely, for maintaining the quality of the vacuum and for preserving the magnetic properties of the ferrite. Equipping window frame magnets with a shorted coil, which can be executed rather easily on existing magnets, has been shown to serve the same purpose, although not as effectively as the diamagnetic barrier.<>