Electron clearing in the Los Alamos Proton Storage Ring

The instability observed in the Los Alamos Proton Storage Ring (PSR) has been tentatively identified as an electron-proton instability. A source of electrons must exist for this instability to occur. The PSR injection section contains the stripper foil, and therefore provides several strong sources of electrons. We have installed an electron clearing system in the injection section to clear out these electrons. The system comprises: (1) a foil biasing system to clear the secondary emission and thermionic electrons, (2) a pair of low-field bending magnets with a Faraday cup to clear the convoy electrons, and (3) two pairs of clearing electrodes, one upstream and one downstream of the stripper foil, to clear the remaining electrons. In this paper we will discuss the design and performance of the Electron Clearing System, and its effect on the instability. We will also present some results from other charge-collection experiments that suggest there is also substantial electron production in parts of the ring other than the injection section