An RFQ beam preparation system for SHIPTRAP

A radio frequency quadropole (RFQ) system for beam preparation, reduction and matching of the phase-space has been developed for the Penning trap facility SHIPTRAP. The system consists of an RFQ cooler, an RFQ mass filter and an RFQ buncher and will allow to cool, mass separate and bunch the nuclei of interest from unwanted species, which contaminate the ion sample and often deteiorate the quality of the measurement, sometimes even obscure the measured data. The targeted performance of the mass filter are highest possible transmission at unit mass resolution. For this purpose the RFQ cooler, mass filter and buncher have been developed and built in a matched combination. High quality RF coils have been built, which enable RF voltages with amplitudes up to 2 kV, and the RF voltage has been stabilized to the level of 0.1%. For highest quality of the extracted ion bunches RF-free, dipolar extraction from the RF buncher has been implemented. The RF-free extraction of the buncher has been realised using a special damping circuit. In order to increase its efficiency, the RFQ buncher is designed as a two stage trap system.