PAC09 - List of Authors (Long, C.D.)

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Long, C.D.

Paper	Title	Page
TH6REP012	Low-Energy Emittance Studies with the New SNS Allison Emittance Scanner	3974
	M.P. Stockli, S. Assadi, W. Blokland, T.V. Gorlov, B. Han, C.D. Long, T.R. Pennisi ORNL, Oak Ridge, Tennessee
	*Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.** The new SNS Allison emittance scanner measures emittances of 65 kV ion beams over a range of ± 116 mrad. Its versatile control system allows for time-dependent emittance measurements synchronized by an external trigger, and therefore is suited for studying pulsed systems. After a programmable delay the system acquires a variable array of beam current measurements, each averaged over a changeable time span. The baseline of the current measurements are determined by averaging a fraction of 1 ms shortly before the start of the ion beam pulse. This paper presents the time evolution of emittance ellipses during the 1 ms H^- beam pulses emerging from the SNS test LEBT, which is important for loss considerations. In addition it presents the time evolution of emittance ellipses during the 3 week active lifetime of an SNS H^- source, which is an operational issue. Additional emittance data characterize the dependence on the electron-dump voltage, the extractor voltage, and the LEBT lens voltages, all of which were critical for reaching the 38 mA baseline H^- beam current. Emittance data for the dependence on the beam current highlight the challenges for the SNS power upgrade.

Paper

Title

Page

TH6REP012

Low-Energy Emittance Studies with the New SNS Allison Emittance Scanner

3974

M.P. Stockli, S. Assadi, W. Blokland, T.V. Gorlov, B. Han, C.D. Long, T.R. Pennisi
ORNL, Oak Ridge, Tennessee

Funding: *SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.

The new SNS Allison emittance scanner measures emittances of 65 kV ion beams over a range of ± 116 mrad. Its versatile control system allows for time-dependent emittance measurements synchronized by an external trigger, and therefore is suited for studying pulsed systems. After a programmable delay the system acquires a variable array of beam current measurements, each averaged over a changeable time span. The baseline of the current measurements are determined by averaging a fraction of 1 ms shortly before the start of the ion beam pulse. This paper presents the time evolution of emittance ellipses during the 1 ms H^- beam pulses emerging from the SNS test LEBT, which is important for loss considerations. In addition it presents the time evolution of emittance ellipses during the 3 week active lifetime of an SNS H^- source, which is an operational issue. Additional emittance data characterize the dependence on the electron-dump voltage, the extractor voltage, and the LEBT lens voltages, all of which were critical for reaching the 38 mA baseline H^- beam current. Emittance data for the dependence on the beam current highlight the challenges for the SNS power upgrade.