Paper |
Title |
Page |
TUPLT166 |
Beam Invariants for Diagnostics
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1518 |
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- V.V. Danilov, A.V. Aleksandrov
ORNL/SNS, Oak Ridge, Tennessee
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This paper deals with some measurable quantities of beams preserved under symplectic transformations. General beam distributions have no determined area, and rms quantities of the beam do not provide invariants in general nonlinear case. It is shown, though, that in the 1D case there exist some integral and local invariants, directly linked to Liouville's theorem. Beam invariants, related to general properties of symplectic transformations, are also found and presented for 2D and 3D cases. If measured at different locations, they can tell whether the transformation is symplectic or there exist diffusion, friction, or other non-Hamiltonian dynamic processes in the beam.
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TUPLT168 |
SNS Beam Commisioning Status
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1524 |
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- S. Henderson, A.V. Aleksandrov, S. Assadi, W. Blokland, C. Chu, S.M. Cousineau, V.V. Danilov, G.W. Dodson, J. Galambos, M. Giannella, D.-O. Jeon, S. Kim, L.V. Kravchuk, M.P. Stockli, E. Tanke, R.F. Welton, T.L. Williams
ORNL/SNS, Oak Ridge, Tennessee
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The Spallation Neutron Source accelerator systems will provide a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron production. The accelerator complex consists of an H- injector capable of producing 38 mA peak current, a 1 GeV linear accelerator, an accumulator ring and associated transport lines. The linear accelerator consists of a Drift Tube Linac, a Coupled-Cavity Linac and a Superconducting Linac which provide 1.5 mA average current to the accumulator ring. The staged beam commissioning of the accelerator complex is proceeding as component installation progresses. In three separate beam commissioning runs, the H- injector and Drift Tube Linac tanks 1-3 have been commissioned at ORNL. Several important performance goals have been achieved, namely 38 mA peak beam current, 1 msec beam pulse length and 1 mA average beam current. Results and status of the beam commissioning program will be presented.
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WEOBCH02 |
Design, Construction, and Initial Operation of the SNS MEBT Chopper System
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150 |
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- R.A. Hardekopf, S.S. Kurennoy, J. Power
LANL, Los Alamos, New Mexico
- A.V. Aleksandrov, D.E. Anderson
ORNL/SNS, Oak Ridge, Tennessee
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The chopper system for the Spallation Neutron Source (SNS) provides a gap in the beam for clean extraction from the accumulator ring. It consists of a pre-chopper in the low-energy beam transport (LEBT) and a faster chopper in the medium-energy beam transport (MEBT). We report here on the final design, fabrication, installation, and first beam tests of the MEBT chopper. The traveling-wave deflector is a meander-line design that matches the propagation of the deflecting pulse with the velocity of the beam at 2.5 MeV, after the radio-frequency quadrupole (RFQ) acceleration stage. The pulser uses a series of fast-risetime MOSFET transistors to generate the deflecting pulses of ± 2.5 kV with rise and fall times of 10 ns. We describe the design and fabrication of the meander line and pulsers and report on the first operation during initial beam tests at SNS.
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Video of talk
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Transparencies
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THPLT167 |
SNS Laser Profile Monitor Progress
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2849 |
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- W. Blokland, A.V. Aleksandrov, S. Assadi, C. Deibele, W. Grice, S. Henderson, T. Hunter, P. Ladd, G.R. Murdoch, J. Pogge, K. Potter, T.J. Shea, D. Stout
ORNL/SNS, Oak Ridge, Tennessee
- V. Alexandrov
BINP SB RAS, Protvino, Moscow Region
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SNS will use a Nd:YAG laser to measure transverse profiles in the 186-1000 MeV super-conducting LINAC (SCL) and Ti:Sapphire modelock laser to measure longitudinal profiles in the 2.5 MeV Medium Energy Beam Transport (MEBT). The laser beam is scanned across the H- beam to photo-neutralize narrow slices. The liberated electrons are collected to provide a direct measurement of the transverse or longitudinal beam profile. We have successfully measured the transverse profile with a prototype system on the MEBT beam. The final SCL system uses an optical transport line that is installed alongside the 300 meter super-conducting LINAC to deliver laser light at 8 locations. Possible vibrations in the optical transport system can lead to inaccuracies in the profile measurement. We will use an active feedback system on a mirror to correct any vibration up to 2 KHz. In this paper we describe our vibration studies and vibration cancellation system as well as the progress in the design, installation and testing of various subsystems for both the transverse and the longitudinal profiles.
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