SPACE-CHARGE-DOMINATED BUNCHED BEAMS IN THE FREQUENCY-DOMAIN

The effect of space charge on high-phase-space-density bunched beams i n an ion storage ring with electron cooling is investigated in the fre quency domain for bunches in the vicinity of the local microwave insta bility threshold. Space charge causes a splitting of synchrotron satel lites into incoherent and coherent lines. Results of measurements of t he splitting and shift are compared with analytical formulas as well a s with simulation of the noise spectra by multiparticle computer simul ation. Coherent frequencies of the quadrupole and sextupole modes of G aussian bunches are found to deviate slightly from the analytical mode frequencies. Consequences for the interaction with narrow-band impeda nces and on the possible accuracy of Delta p/p momentum-spread measure ments for high-phase-space-density bunches are briefly discussed.