Stripline beam position monitor modelling and simulations for charge measurements

Strip line Beam Positions Monitors (BPMs) are the main devices used for non-intercepting position measurement for the electron LINAC of ELI-NP (Extreme Light Infrastructure - Nuclear Physics). All the 29 BPMs have the same design, with the exception of the one installed in one of the dump line, which has a much larger acceptance than the others. BPMs will also be used to measure the charge of the beam, by measuring the sum of the pickups signals and calibrating it with beam charge monitors installed along the LINAC. An analytical model has been developed for the proposed BPMs. This model has been checked by means of electromagnetic simulations, in order to obtain the pickups signals at the passage of the beam and to study the effects of BPMs non-linearities, particularly on charge measurements. Details of the analytical model, results of the numerical simulations and the correction algorithm proposed for charge measurements are described in this paper.