Spiral2 Beam Position Monitor calibration

by Paul-Éric Laqua

Beam Position Monitors (BPM) of the Spiral2 accelerator are beam diagnostics dedicated to the measuring of positions (X and Y), ellipticity and phase of ion beams in the LINAC.

Four BPM electrodes, around the beam tube, are sensitive to variations of the electric field induced by ion bunch transit. BPM electronic cards amplify and process electrode signals to obtain position, ellipticity and phase.

In order to reach accuracy requirements, all instrumentations must be calibrated between them, in magnitude and phase, to equalize gain and phase of measuring channels.

The first task of my internship consisted of developing and approving new calibration devices, designed to automate these calibrations. The second was to use these devices in the Spiral2 accelerator to calibrate the 20 BPMs. The last is to analyze correcting coefficients and the measurement results.