Beam current measurements at the TSR Heidelberg

To conduct experiments using low energy ion beams at the TSR heavy ion storage ring, the beam deceleration process must be well understood. During deceleration of the beam the revolution frequency decreases, resulting in low current, which is difficult to measure with a common DC transformer. However the number of particles in a bunch can also be determined by measuring the voltage signal in the time domain using a capacitive pick-up. If the ratio of bunch length and RF period does not change during deceleration or acceleration, measuring the pick up signal spectrum is a more sensitive method, where the signal is directly proportional to the number of particles in a bunch. A summery of these different methods to determine the number of particles is presented.