LBNL, Berkeley, California
Typically storage ring light sources operate with the maximum number of bunches possible with a gap for ion clearing. The Advanced Light Source (ALS) has 2 nanoseconds between the bunches and typically operates with 276 bunches out of a possible 328. For experimenters doing timing experiment this bunch separation is too small and would prefer to see only one or two bunches in the ring. In order to provide more flexible operations and substantially increase the amount of operating time for time-of-flight experimenters, it is being proposed to kick one bunch on a different vertical closed orbit. By spatially separating the light from this bunch from the main bunch train in the beamline, one could potentially have single bunch operation all year round. By putting this bunch in the middle of the ion clearing gap the required bandwidth of the kicker magnets is reduced. Using one kicker magnet running at the ring repetition rate (1.5 MHz), this bunch could be permanently put on a different closed orbit. Using multiple kicker magnets, this bunch could be locally offset at an arbitrary frequency. This paper will show some first results using such a system.
This work was supported by U.S. Department of Energy under Contract No. DE-AC03-76SF00098
Bira, Albuquerque, New Mexico
National Instruments, Austin
LANL, Los Alamos, New Mexico
The design and test of a new beam-profile-wire-scanner actuator for the LANSCE* 800-MeV proton linear accelerator is described. Previous actuator implementations use open-loop stepper-motor control for position indexing. A fixed-frequency, fixed-duration pulse train is sent to the stepper motor driving the linear actuator. This has lead to significant uncertainties in position, mechanical resonances and electrical noise. A real-time, closed loop control system has been developed at tested for more repeatable and accurate positioning of beam sense wires. The use of real-time controller allows one to generate a velocity profile for precise, resonance-free wire position indexing. High radiation levels in the beam tunnel, dictate the use of an electro-magnetic resolver, typically, used in servo applications, as the position feedback element. Since the resolver is an inherently analog device sophisticated digital signal processing is required to generate and interpret the wave forms that the feedback mechanism needs for positioning. All of the electronic and computational duties are handled in one National Instruments compact RIO real-time chassis with FPGA.**
*Los Alamos Neutron Science Center
**Field Programmable Gate Array
UMD, College Park, Maryland
I review the state of the art of diagnostics based on transition, diffraction and Smith Purcell radiation in the optical to millimeter wave band, which are currently being used to measure the transverse and longitudinal parameters of charged particle beams. The properties and diagnostic capabilities of both the incoherent and coherent forms of each type of radiation are described. Examples of TR, DR and SPR diagnostics for electron and proton beams are presented.
