Optimisation of Planar Electrodes for Stochastic Beam Cooling

Member of the Graduiertenkolleg (DFG GK-GRK 410/1) In the new GSI project stochastic cooling of secondary particles will be used. The efficiency of stochastic cooling is mainly influenced by the coupling of the electrodes to the beam. This performance has to be investigated and optimised. The investigation is done via a three dimensional numerical electromagnetic field analysis with use of the simulation package “CST Microwave Studio” [1]. The basic planar structure for starting the optimisation is explained in [2]. It consists of a slotline on the upper side of a substrate, which couples directly to the beam. The signal is then obtained by means of a microstrip line on the lower side of the substrate. As already mentioned in [2], an improvement is possible by countersinking the slotline. For that purpose the slotline/microstrip-line transition had to be optimised again taking the sinking into account. The optimisation goal was a minimum reflection coefficient.