Intense H−beams have been extracted from a large multicusp plasma source operated with cesium seeding. The H−beams were accelerated up to 100 keV by a single‐stage or a two‐stage electrode system. Spatial profiles of the beams are measured calorimetrically and the beam divergence angle is obtained from half of thee‐folding width. A minimum beam divergence angle of 5 mrads is achieved at a H−current density of 30 mA/cm2with a beam energy of 100 keV. The ratio of acceleration current to H−current increases abruptly when a H−current saturates in the space charge limited region. This enhancement is mainly due to secondary electrons caused by the intersection of H−beams with an extraction grid. When the operating gas pressure decreases, the ratio of the acceleration current to the H−current decreases. This is related to a stripping loss of H−ions in the electrodes. A beam divergence angle reaches a minimum when a ratio ofVacctoVextis set at an optimum value of 1.6 in the single‐stage acceleration. This ratio is almost the same as that in the double‐stage acceleration, where the optimum ratio ofEaccl/Eextis 1.5. In the optimumEaccl/Eextratio the divergence angle is not affected byVacc2. The divergence angle can be reduced by changingVacc2even if the ratio ofEaccl/Eextis not optimized. The beam steering effect by permanent magnets buried in an extraction grid is observed in nine beamlets experiments. A simple calculation of a single particle trajectory gives a good approximation of the beam deflection angle. ©1995 American Institute of Physics.