First characterization of the SPIDER beam

The present contribution will outline the activities and the beam operations in the SPIDER beam source during its first year of operation with volume generation of negative ions. In order to extend the source pressure range and to provide a thorough investigation of the properties of the early SPIDER beams, a mask was installed in the accelerator, leaving only isolated beamlets (for a total number of ~100 beamlets out of 1280). During the first extraction of negative particles from the source, the features of the co-extracted electrons were studied and correlated with the plasma parameters. Particularly, the magnetic filter field effectiveness in reducing the co-extracted electron current was verified; correspondingly, the decrease of the plasma emissivity was studied as well as the influence on the negative ion current. The first characterisation of the SPIDER beam, in terms of beamlet divergence and deflection, is proposed and compared with numerical models while varying the source parameters; the negative ion beam exhibits values of current density and optical properties similar to those expected in volume operation.