Electron cloud instabilities in the Proton Storage Ring and Spallation Neutron Source

Abstract

Electron cloud instabilities in the Los Alamos Proton Storage Ring and those foreseen for the Oak Ridge Spallation Neutron Source are examined theoretically, numerically, and experimentally.

Mechanism of electron multipacting with a long-bunch proton beam

“…5). The effect of the longitudinal beam profile was first studied at the PSR [30], followed by analysis [17] and simulations [20].…”

“…Many studies explored electron-cloud buildup in long-bunch proton machines using numerical methods [17,18,[20][21][22]. We know from PSR experiments and the simulations described in this paper that the buildup depends on several factors, such as the shape of the beam's longitudinal and, transverse profiles, intensity, chamber size, and secondary emission yield (SEY).…”

“…One of our objectives was to quantify the mechanism of multipacting in the long proton beam. Previous studies analyzed electron motion and energy gain [17,18]; however, we made a more detailed analysis of electron motion under the beam's spacecharge force and dipole magnetic fields. Knowledge of the electron's motion and energy when it hits the chamber's surface is most helpful in elucidating the mechanism of electron multipacting.…”

Numerical simulation of the generation of secondary electrons in the High Current Experiment

“…Researchers have used the POSINST code to study electron effects in the Los Alamos Proton Storage Ring [1], the Argonne Advanced Photon Source [13], the Spallation Neutron Source [14], and the CERN Large Hadron Collider [15]. The POSINST routines approximate the true secondary …”

“…Electron effects presently limit the performance of many ion accelerators [1][2][3]. One source of these electrons is electrons emitted from collisions between beam ions and the beam pipe walls.…”