A new delay-line kicker with capacitive loading sandwiches

Abstract

Abstract The delay-line type of kicker for the in- and ejection into and from cyclic accelerators is the right choice if extremely fast rise and fall times are required. It will be shown that it may be operated at 1 3 of the wave impedance of the pulse generator as compared to the lumped element solution with a corresponding reduction in the pulse voltage [1]. The pulse generator charge voltage will be reduced by a factor of 1.5. However, low wave impedance requires high capacitive loading for which the usual construction of delay-line magnets is prohibitive since is makes use of longitudinal subdivision of the ferritic core of the magnet into a number of individual cells, each cell consisting of a piece of ferrite followed by a capacitive plate connected to the magnet conductor. For decreasing cell length the percentage of longitudinal space occupied by the capacitive plate increases with a corresponding increase in overall length and a decrease in magnetic length. Therefore in practice there exists a lower limit for the cell length and the associated cell inductance. This in turn introduces a lower limit for the wave impedance since the capacitive loading would lead to unacceptable bulky capacitor units. In this article a straightforward modification of the usual design of delay-line kickers will be described with a picture frame ferrite geometry as it is used for lumped element kickers and capacitive loading units being attached to the core like sandwiches. This approach offers a number of advantages compared to the conventional solution.