High q-resolution electron gun for low energy electron diffraction

We present a new unipotential electron gun design for low energy electron diffraction. The gun has excellent spatial resolution. With a 170-mm gun-to-detector working distance, it produces a spot between 50 and 114 μm in diameter for energies between 500 and 100 eV, respectively. These specifications make it ideal for high q-resolution studies of surface defects. The unipotential design offers independent beam energy and current control without refocusing, and operates at beam currents as high as 25 nA (near the space-charge limit). The operating current of this gun is 10–40 times higher than existing guns with similar spatial properties.