The beam emittance of negative ion sources

A computer controlled emittance meter has been used to measure the emittance of various beams produced by the three ion sources installed at the Strasbourg Tandem injector: the direct extraction duoplasmatron source, the penning source and the cesium sputter ion source (model 860). The RMS emittance and the emittance enclosing 90% of the beam intensity were extracted and compared. The shape of emittance contours and the fractional intensity emittance were analyzed. For the three sources, an emittance value smaller than 5π.mm.mrad.MeV1/2 was found for a beam intensity ranging from 500 to 2500 nA