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| MOOBS1 |
Beam Dynamics Issues in the SNS Linac |
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- A.P. Shishlo
ORNL, Oak Ridge, Tennessee, USA
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Funding: This research is supported by UT-Battelle, LLC for the U. S. Department of Energy under contract No. DE-AC05-00OR22725
A review of the Spallation Neutron Source (SNS) linac beam dynamics is presented. It describes transverse and longitudinal beam optics, losses, activation, and comparison between the initial design and the existing accelerator. The SNS linac consists of normal conducting and superconducting parts. The peculiarities in operations with the superconducting part of the SNS linac (SCL), estimations of total losses in SCL, the possible mechanisms of these losses, and the progress in the transverse matching are discussed.
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Slides MOOBS1 [1.270 MB]
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| MOOBS2 |
Status of High Intensity Effects in the Spallation Neutron Source Accumulator Ring |
17 |
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- S.M. Cousineau
ORNL, Oak Ridge, Tennessee, USA
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Funding: This research is supported by UT-Battelle, LLC for the U. S. Department of Energy under contract No. DE-AC05-00OR22725
The 248-meter Spallation Neutron Source (SNS) accumulator ring has accumulated up to 1.55·1014, 1 GeV protons. At this intensity, space charge effects contribute significantly to the beam dynamics. Here we present observations of space charge effects in the SNS ring, with emphasis on space charge effects and e-p instabilities.
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Slides MOOBS2 [3.704 MB]
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| MOOBS3 |
Bunch-End Interpenetration During Evolution to Longitudinal Uniformity in a Space-Charge-Dominated Storage Ring |
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- T.W. Koeth, B.L. Beaudoin, S. Bernal, I. Haber, R.A. Kishek, P.G. O'Shea
UMD, College Park, Maryland, USA
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The University of Maryland Electron Ring is a facility for study of the novel physics that occurs as intense space-charge-dominated beams that are transported over long distances. An example presented here is the role of space-charge longitudinal expansion and bunch-end interpenetration in the relaxation of a coasting bunch towards uniformly filling the ring. By comparing experiment to simplified longitudinal simulations the relaxation process is shown to be largely independent of details of the transverse dynamics. However, to get detailed agreement it was found necessary to include the consequences of transverse current loss. Since the AC coupled diagnostics lose information on any DC current loss, a novel beam knockout technique was developed to recover this information.
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Slides MOOBS3 [2.501 MB]
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| MOOBS4 |
Electron Cloud Experiments at Fermilab: Formation and Mitigation |
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- R.M. Zwaska
Fermilab, Batavia, USA
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We have performed a series at Fermilab to explore the Electron Cloud phenomenon. The Main Injector will have its beam intensity increased four-fold in the Project X upgrade, and would be subject to instabilities from the Electron Cloud. We present measurements of the Cloud formation in the Main Injector and experiments with materials for the mitigation of the Cloud. An experimental installation of Titanium-Nitride (TiN) coated beam pipes has been under study in the Main Injector since 2009; this material was directly compared to an adjacent stainless chamber through Electron Cloud measurement with Retarding Field Analyzers (RFAs). Over the long period of running we were able to observe the secondary electron yield (SEY) change and correlate it with electron fluence, establishing a conditioning history. Additionally, the installation has allowed measurement of the electron energy spectrum, comparison of instrumentation techniques, and energy-dependent behavior of the Electron Cloud. Finally, a new installation, developed in conjunction with Cornell and SLAC, will allow direct SEY measurement of material samples irradiated in the accelerator.
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Slides MOOBS4 [2.975 MB]
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