DIRECT OBSERVATION OF INDIVIDUAL SPEAR ELECTRON BUNCH ORBIT OSCILLATIONS AT FREQUENCIES ABOVE 30 KHZ

Using a prototype detector being developed for time-resolved X-ray dif fraction, we have recently been able to observe oscillations in SPEAR electron bunch orbits at frequencies corresponding to various resonanc es in the rf power system. In spite of the fact that the SPEAR beam st eering feedback systems were turned on and the orbit was nominally sta ble, we observed intensity fluctuations of +/- 10% or more at frequenc ies corresponding to various synchrotron resonances in SPEAR. These in tensity fluctuations arise from vertical fluctuations in either orbit location sigma(y) or trajectory sigma(y)'. The experimental geometry i mplies that sigma(y) and sigma(y)' can easily be as large as 1.3 mm an d 67 murad, respectively. Different oscillation patterns were seen for the different bunches during the same time frame, implying that each bunch is following its own trajectory and interacting differently with the system resonances. Changes in the single bunch patterns were some times observed in times less than 50 mus. The existence of these oscil lations has important implications both for machine physicists respons ible for beam-position control at the new storage rings and for users considering fast, time-resolved experiments.