Conceptual design of a vacuum system for a compact, high luminosity CESR upgrade

Abstract

A conceptual design study for a vacuum system for a possible compact high luminosity upgrade to CESR is presented. The vacuum chamber consists of an elliptical cross-section beam chamber connected to a pumping chamber by holes recessed in several channels in the beam chamber wall. Recessing the hole provides a decrease in the impedance of the beam chamber while still providing protection to the pumping chamber from RF fields generated by the beam. The beam chamber has a very compact cross-section compatible with two-in-one quadrupole magnets and inexpensive compact dipole magnets. Pumping will be provided by a combination of nonevaporable getter (NEG) and ion pumps. Calculations were carried out of the impedance and loss factor of the chamber as well as transmission of RF field power through the slots and the conductance of the pumping slots. We have also calculated the linear synchrotron radiation power density and the pressure profile and beam-gas lifetime for this chamber and pump configuration. We consider the time between necessary NEG pump reactivations and the total capacity of the pumps.