Experimental study of space-charge waves in heavy ion beams

When a short-duration, small-amplitude energy perturbation is applied to a heavy-ion beam, positive- and negative-going longitudinal space-charge waves are generated on the beam. Longitudinal diagnostic kickers that provide ∼1% energy perturbation have been implemented for generating space-charge waves on HCX and NTX beams. The kickers consist of specially designed fast pulse generators combined with an existing aperture or ESQ structure to provide the longitudinal perturbation to the beam. The amplitudes of the resulting density waves are ∼10%, measured a few meters downstream of the kicker. The time-of-flight (TOF) of the wave provides an accurate measure of the beam energy. The TOF measurements will be described. Comparison of measured waves with a simple 1-D fluid model of the beam will be presented.