Quadrupolar Mode Measurements for Space Charge Dominated Beams

On-line monitoring of beam quality requires non-invasive transverse phase space diagnostics. Emittance measurement is particularly challenging for high-intensity particle beams since space charge complicates the beam dynamics during measurement. Quadrupolar mode measurements have been empirically shown to provide information about the beam emittance, but so far only for small relative space charge effects, where the results depend on a linear theory. We present a quadrupolar mode measurement for space charge dominated beams with unsplit tunes using multi-turn resonant excitation. Results from experiments performed at the University of Maryland Electron Ring are compared to both analytic and numerical analysis of the rms envelope equations.