A compact neutron generator has an ion source with a multi-hole spherical extraction system and a curved magnetic filter. A deuterium ion (or deuterium and tritium ion) plasma is produced by RF excitation in a plasma ion generator using an RF antenna. The multi-hole spherical extraction system of the ion source has three electrodes--plasma electrode, extraction electrode, suppressor electrode--which are used to expand a high current ion beam in a short distance. A large area spherical neutron generating target is positioned to receive the expanded ion beam from the ion generator. The extraction system and neutron generating target may alternatively be implemented with a cylindrical geometry instead of spherical, with slots instead of holes.