AUTOMATED BEAM OPTIMISATION AND DIAGNOSTICS AT MAMI

摘要

At the Institut fur Kernphysik (IKPH) of Mainz University the fourth stage of the Mainz Microtron (MAMI), a 0.855 to 1.5 GeV Harmonic Double Sided Microtron (HDSM), is now on the verge of first operation [1]. To provide an automated beam optimisation, low-Q-TM010 and TM110 resonators at each linac of the three cascaded Racetrack Microtrons (RTM) and the two linacs of the new HDSM are used. These monitors deliver position, phase and intensity signals of each recirculation turn when modulating the beam intensity with 12 ns-pulses (diagnostic pulses, 30 bunches, maximum repetition rate 10 kHz). For operating the HDSM an extended system for displaying and digitising these signals was developed. Highbandwidth ADCs with at least 500 MS/s and memory for digitising up to 256 kpoints allow very comfortable to analyse, calibrate and automatically optimise the beam positions and phases during operation. The system is also used to adjust the transversal and longitudinal focussing according to the design parameters. Synchrotron radiation monitors allow to display beam sizes and positions out of the bending magnets for each turn. Another synchrotron radiation monitor provides the shape of all turns superimposed at the common entrance of the beam into the dipole magnet after passing the linac axis. These monitors are very helpful tools for beam-matching between the RTMs. Therefore similar systems were planned and constructed for the HDSM.