Design of slug tuners for the spiral2 RFQ

Tuner parameters: number (or separation distance), diameter and position range, are determined in order to fit two main requirements: (1) compensation of construction errors specified between given bounds, and (2) compatibility with magnetic-field bead-pull measurements. Tuner slopes possibly derived from 2D or 3D simulations are compared. RFQ 4-wire transmission line model is used to calculate tuner position range required to compensate for given capacitance relative errors. The position of the bead guiding-wire is deduced from 3D field maps and magnetic-field-to-voltage calibration accuracy requirement.