DESIGN AND PERFORMANCE OF THE BIASED DRIFT TUBE SYSTEM IN THE BNL ELECTRON LENS

The Electron Lenses [1] in RHIC are designed with a series of biased drift tubes through which the electron beam propagates in the opposite direction of the RHIC ion beams. An electric field gradient created by selectively biased drift tubes sweeps out ions generated through residual gas ionization and trapped in the central longitudinal magnetic field where the electron beam interacts with the RHIC beam. The image currents induced on the drift tubes by the RHIC beam develop high voltages at RF frequencies that are detrimental to the electron and ion beams. This paper presents the design of the biased drift tube system along with the commissioning results of the DC bias and instrumentation features.