Measurement of electric field uniformity in an electrostatic separator

Electrostatic separators are used in several modern storage rings to generate large distortions of the closed orbit as a means of avoiding undesirable beam-beam collisions in the arcs. Unlike comparable magnetic elements, there is not a well developed technology to measure the electric field quality of electrostatic separators, so the ultimate field uniformity is largely left up to the conservatism and skill of the designers and fabricators of the devices. Measurements of the electric field integrate over the entire path of the particles, including end effects, and sense the effects of misalignments, warpage and other mechanical errors on individual units. This ability not only helps with quality control, but also to interpret machine studies where the results are sensitive to the nonuniformities of the electric field. In particular, electric field measurements can provide a better estimate of the tuneshift and sextupole moments as a function of beam position in the separators