PAC07 - List of Authors (McCrady, R. C.)

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

McCrady, R. C.

Paper	Title	Page
MOPAS050	Active Damping of the e-p Instability at the LANL PSR	548
	R. C. McCrady, R. J. Macek, S. B. Walbridge, T. Zaugg LANL, Los Alamos, New Mexico S. Assadi, C. Deibele, S. Henderson, M. A. Plum ORNL, Oak Ridge, Tennessee J. M. Byrd LBNL, Berkeley, California S.-Y. Lee IUCF, Bloomington, Indiana M. T.F. Pivi SLAC, Menlo Park, California
	Funding: This work was supported by the United States Department of Energy under contracts DE-AC52-06NA25396 and W-7405-ENG-36. A prototype of an analog, transverse (vertical) feedback system for active damping of the two-stream (e-p) instability has been developed and successfully tested at the Los Alamos National Laboratory Proton Storage Ring (PSR). This system was able to improve the instability threshold by approximately 30% (as measured by the change in RF buncher voltage at instability threshold). Evidence obtained from these tests suggests that further improvement in performance is limited by beam leakage into the gap at lower RF buncher voltage and the onset of instability in the horizontal plane, which had no feedback. Here we describe the present system configuration, system optimization, results of several recent experimental tests, and results from studies of factors limiting its performance.
MOPAS080	A Digital Ring Transverse Feedback Low-Level RF Control System	617
	A. K. Polisetti, S. Assadi, C. Deibele, J. C. Patterson ORNL, Oak Ridge, Tennessee R. C. McCrady LANL, Los Alamos, New Mexico M. J. Schulte UW-Madison, Madison, Wisconsin
	A digital wide-band system for damping ring instabilities in an accelerator is presented. With increased beam intensity, the losses of an accumulator ring tend to increase due to the onset of various instabilities in the beam. An analog feedback damper system has been implemented at Los Alamos National Laboratory. This analog system, while functional, has certain limitations and a lack of programmability, which can be overcome by a digital solution. A digital feedback damper system is being designed through a collaborative effort by researchers at Oakridge National Laboratory, Los Alamos National Laboratory, and the University of Wisconsin. This system, which includes analog-to-digital converters, field programmable gate arrays and digital-to-analog converters can equalize errors inherent to analog systems, such as dispersion due to amplifiers/cables, gain mismatches, and timing adjustments. The digital system features programmable gains and delays, and programmable equalizers that are implemented using digital FIR and comb filters. The flexibility of the digital system allows it to be customized to implement different configurations and extended to address other diagnostic problems.
TUODAB02	Electron Cloud Generation and Trapping in a Quadrupole Magnet at the LANL PSR	828
	R. J. Macek, J. E. Ledford, R. J. Macek TechSource, Santa Fe, New Mexico M. J. Borden, A. A. Browman, R. C. McCrady, J. F. O'Hara, L. Rybarcyk, T. Spickermann, T. Zaugg LANL, Los Alamos, New Mexico M. T.F. Pivi SLAC, Menlo Park, California
	Funding: Work supported by DOE SBIR Grant No. DE-FG02-04ER84105 and CRADA No. LA05C10535 between TechSource, Inc. and the Los Alamos National Laboratory. Recent beam physics studies on the two-stream e-p instability at LANL proton storage ring (PSR) have focused on the role of the electron cloud generated in quadrupole magnets where electrons, which seed beam-induced multipacting, are expected to be largest due to grazing angle losses from the beam halo. A new diagnostic to measure electron cloud formation and trapping in a quadrupole magnet has been developed, installed, and successfully tested at PSR. Experimental results will be presented on various characteristics of electron cloud obtain from experiments using this diagnostic and compared with simulations. Results include data on flux and energy spectra of electrons striking the vacuum chamber, the line density and lifetime of electrons trapped in the quadrupole after the beam has been extracted as well as evidence regarding electrons ejected from the magnet during passage of the proton beam.
	Slides
WEXC01	Experimental Tests of a Prototype System for Active Damping of the E-P Instability at the LANL PSR	1991
	C. Deibele, S. Assadi, V. V. Danilov, S. Henderson, M. A. Plum, A. K. Polisetti ORNL, Oak Ridge, Tennessee J. M. Byrd LBNL, Berkeley, California J. D. Gilpatrick, R. C. McCrady, J. F. Power, T. Zaugg LANL, Los Alamos, New Mexico S.-Y. Lee IUCF, Bloomington, Indiana M. T.F. Pivi SLAC, Menlo Park, California M. J. Schulte, Z. P. Xie UW-Madison, Madison, Wisconsin
	Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U. S. Department of Energy under contract DE-AC05-00OR22725. A prototype of an analog, transverse (vertical) feedback system for active damping of the two-stream (e-p) instability has been developed and successfully tested at the Los Alamos Proton Storage Ring (PSR). This talk describes the system configuration, results of several experimental tests and studies of system optimization along with studies of the factors limiting its performance.
	Slides
FRPMS051	Proposed Beam Diagnostics Instrumentation for the LANSCE Refurbishment Project	4099
	J. D. Gilpatrick, B. Blind, M. J. Borden, J. L. Erickson, M. S. Gulley, S. S. Kurennoy, R. C. McCrady, J. F. O'Hara, M. A. Oothoudt, C. Pillai, J. F. Power, L. Rybarcyk, F. E. Shelley LANL, Los Alamos, New Mexico
	*Funding: Work supported by the U. S. Department of Energy.** Presently, the Los Alamos National Laboratory is in the process of planning a refurbishment of various sub-systems within its Los Alamos Neutron Science Center accelerator facility. A part of this LANSCE facility refurbishment will include some replacement of and improvement to existing older beam diagnostics instrumentation. While plans are still being discussed, some instrumentation that is under improvement or replacement consideration are beam phase and position measurements within the 805-MHz side-coupled cavity linac, slower wire profile measurements, typically known as wire scanners, and possibly additional installation of fast ionization-chamber loss monitors. This paper will briefly describe the requirements for these beam measurements, what we have done thus far to answer these requirements, and some of the technical issues related to the implementation of these instrumentation.