The optics, emittance, and brightness of the reflected beam sputter source

The emittance of the reflected beam sputter source is shown to be low, and the brightness high. However, the emittance is very variable. The internal optical behaviour of the source has been found to be complex, and to depend strongly on space charge. This adversely affects the stability of the negative ion beam, and causes the variability seen in the emittance. The source, and hence the beam, lacks symmetry, and this lack adversely affects its matching properties and stability. (orig.)