Status of experimental studies of electron cloud effects at the Los Alamos proton storage ring

Various electron cloud effects (ECE) including the twostream (e-p) instability at the Los Alamos Proton Storage Ring (PSR) have been studied extensively for the past five years with the goal of understanding the phenomena, mitigating the instability and ultimately increasing beam intensity. The specialized diagnostics used in the studies are two types of electron detectors, the retarding field analyzer and the electron sweeping detector, which have been employed to measure characteristics of the electron cloud as functions of time, location in the ring and various influential beam parameters. In addition, a short stripline beam position monitor is used to measure high frequency motion of the beam centroid. Highlights of this research program are summarized along with more detail on recent results obtained since the ECLOUD’02 workshop. Recent work includes a number of parametric studies of the various factors that affect the electron cloud signals, studies of the sources of initial or “seed” electrons, additional observations of electron cloud dissipation after the beam pulse is extracted, studies of the “first pulse instability” issue, more data on electron suppression as a cure for the instability, and observations of the effect of a one-turn weak kick on intense beams in the presence of a significant electron cloud.