The purpose of this experiment is to improve the optics of an intenseH−negative-ion beam, to be used in future Tokamaks. The emittance diagnostic has been installed in the experimental setup INCA, to perform an optimization of a negative-ion injector preaccelerator. The first stage of this work consists of testing the operation of the electric-sweep scanner, to measure the beam current in the two-dimensional-phase space and to investigate the diagnostic performances. In addition to the measurement ofH−angles, we can scan the angles of the fastH+created along the beam in the transport region and test the efficiency of the electron magnetic trap installed in the second accelerator grid (extraction electrode). We also observe the presence of a neutral component. This analyzer not only provides a diagnostic of the beam divergence but also improves of the knowledge of the beam components. We studied two accelerator configurations. The first one permitted to obtain an optimal beam optics under 15 keV. Then the accelerator geometry was modified to ensure a higher optimum high voltage. We will show several experimental results performed with two accelerator configurations. ©1998 American Institute of Physics.