A fundamental limit to the polarized current density produced by the Lamb-shift polarized ion source

The Lamb-shift polarized ion source has been shown to be able to produce only 2-3 μA of polarized beam current. The mechanism that is responsible for this limitation has proved elusive over the years. In this paper, we present an explanation for this limitation. We have conducted a proof-of-principle-type of experiment that verifies our hypothesis. The results from the experimental are then used along with well-known properties of the source to predict the limiting current within a factor of two of the observed value. (orig.)