Study of the operation of the Cornell Linac for positron production at high multibunch currents

The Cornell Electron Storage Ring (CESR) operates as an electron-positron collider with 9 trains of 2 to 5 closely spaced bunches per train per beam. The Cornell Linac is the initial component of the injector for CESR and it needs to provide multibunch trains of electrons and positrons at high injection rates for CESR. This paper presents the results of simulations which have studied the effects of operating the Linac at high multibunch currents needed for the production of trains of positron bunches. Results include the effect of longitudinal wakefields induced by the beam in the linac injector prebuncher cavities and a method for the partial compensation of the effect of these wakefields, the effect of transverse wakefields in the linac accelerator sections in the electron linac preceding the positron target and the effect on positron capture of increasing the accelerating gradient in the positron linac. Comparison with some linac measurements is included.