The beam from an EHD ion source using liquid gallium has been shown to have a brigtness of 0.9×105A cm−2 sr−1at 21 kV and an energy spread of 12 eV at 10‐&mgr;A total current. The effective source diameter was 0.2 &mgr;m as imaged by a 2‐cm‐long Einzel lens with a 0.12‐mm aperture. Cesium was significantly poorer and mercury much poorer than gallium.