SLAC, Menlo Park, California
BNL, Upton, Long Island, New York
Life Imaging Technology, Palo Alto, California
As SPEAR3 moves closer to trickle-charge topup injection, the complex phase-space dynamics of the injected beam becomes increasingly important for capture efficiency and machine protection. In the horizontal plane the beam executes ~12mm betatron oscillations and begins to filament within 10's of turns. In the vertical plane the beam is more stable but a premium is placed on flat-orbit injection through the Lambertson septum and the correct optical match. Longitudinally, energy spread in the booster is converted to arrival-time dispersion by the strong R56 component in the transfer line. In this paper, we report on turn-by-turn imaging of the injected beam in both the transverse plane and in the longitudinal direction using a fast-gated ccd and streak camera, respectively.
Stanford University, Stanford, California
SLAC, Menlo Park, California
By operating SPEAR3 in the quasi-isochronous (low-alpha) mode, one can produce synchrotron radiation with pulse durations of order 1ps. Applications include pump-probe x-ray science and the production of THz radiation. Measurements of short pulse lengths are difficult, however, because the light intensity is low and streak camera resolution is of order 2ps. Bunch arrival time and timing jitter are also important factors. In order to further quantify the pulse length and timing system performance, a 5MHz, 50fs mode-locked laser was used to cross-correlate with the visible SR beam in a BBO crystal. The 800nm laser pulse was delayed with a precision mechanical stage and the product SHG radiation detected with a photodiode / lock-in amplifier using the ring frequency as reference. In this paper we report on the experimental setup, preliminary pulse length measurements and prospects for further improvement.
SLAC, Menlo Park, California
The recent progress at the SPEAR3 were the increase in stored current from 100 mA to 200 mA maximum and the top-off injection to allow beamlines to stay open during injection. Presently the booster injects 3.0 GeV beam to SPEAR3 three times a day. The stored beam decays to about 150 mA between the injections. The growing user demands are to increase stored current to the design value of 500 mA, and to maintain it at a constant value within a percent or so. To achieve this goal the booster must inject once every few minutes. For improved injection efficiency, all RF systems at the linac, booster and SPEAR3 need to be phase-locked. These requirements entail a booster RF system upgrade to a scaled down version of the SPEAR3 RF system running at 476.3 MHz with a 1.2 MW cw output power capability. The present booster RF system is basically a copy of the SPEAR2 RF system operating at 358.5 MHz with 80 kW peak power to a 5-cell RF cavity for 1.2 MV gap voltage. We will analyze each subsystem option for their merits within budgetary and geometric space constraints. A substantial portion of the system will come from the decommissioned PEP-II RF stations.