Simulation of RF-focusing in the RFQ matching section by IGUN©

In the design and optimisation of the matching between an ion source and a RFQ there is a lacking tool: Either the program for the calculation of ion extraction and matching to the RFQ (e.g. IGUN) has to stop at the entrance flange of the RFQ, because the RF-focusing of the RFQ electrodes (vanes or rods) cannot be taken into account, or the RFQ simulation program, like PARMTEQ, cannot take into account static electric-field, which originate from the matching lens. We therefore have developed a simple theory, how to take into account the RF-focusing of a RF-quadrupole structure as well as the beam spreading by emittance in a simulation with zero emittance by IGUN. This allows very effective use of IGUN to design the matching between an ion source and the RFQ up to the end of the radial matching section of a RFQ. IGUN automatically takes into account the local focusing strength of the RFQ electrodes to adjust the space-charge spreading by virtually adjusting the beam current. Handling of a finite emittance has also been added to IGUN.