Holmes, J.A.

Paper	Title	Page
TUPLT170	The SNS Beam Power Upgrade	1527
	S. Henderson, S. Assadi, R. Cutler, V.V. Danilov, G.W. Dodson, R.E. Fuja, J. Galambos, J.A. Holmes, N. Holtkamp, D.-O. Jeon, S. Kim, L.V. Kravchuk, M.P. McCarthy, G.R. Murdoch, D.K. Olsen, T.J. Shea, M.P. Stockli ORNL/SNS, Oak Ridge, Tennessee
	The Spallation Neutron Source (SNS) accelerator systems, which consist of an H- injector, a 1 GeV linear accelerator, an accumulator ring and associated transport lines, will provide a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron production. The SNS is presently under construction at Oak Ridge National Laboratory and will begin operations in 2006. Even in the baseline design, many of the accelerator subsystems are capable of supporting higher beam intensities and higher beam energy. We report on upgrade scenarios for the SNS accelerator systems which increase the 1.44 MW baseline beam power to at least 3 MW, and perhaps as high as 5 MW. The increased SNS beam power can be achieved primarily by increasing the H- ion source current, installing additional superconducting cryomodules to increase the final linac beam energy to 1.3-1.4 GeV, and modifying injection and extraction hardware in the ring to handle the increased beam energy. The upgrade beam parameters will be presented, the required hardware modifications will be described, and the beam dynamics implications will be discussed.
TUPLT171	ORBIT Simulations of the SNS Accumulator Ring	1530
	J.A. Holmes, S.C. Bunch, S.M. Cousineau, V.V. Danilov, S. Henderson, A. Shishlo ORNL/SNS, Oak Ridge, Tennessee M. Plum LANL, Los Alamos, New Mexico Y. Sato IUCF, Bloomington, Indiana
	As SNS undergoes construction, many detailed questions arise concerning strategies for commissioning and operating the accumulator ring. The ORBIT Code is proving to be an indispensible tool for addressing these questions and for providing guidance to the physicists and decision makers as operation draws near. This paper shows the application of ORBIT to a number of ring issues including exclusion of the HEBT RF cavities during commissioning, the detailed effect of the injection chicane magnets on the beam, the effects and correction of magnet alignment and multipole errors, debunching of the linac 402.5 MHz beam structure, the injection of self consistent uniform beam configurations, and initial electron cloud simulations.
WEYLH03	Collective Effects and Instabilities in Space Charge Dominated Beams	189
	J.A. Holmes ORNL/SNS, Oak Ridge, Tennessee
	Significant progress in the detailed computational study of collective beam dynamics is being driven by the spectacular increase in computer power. To take advantage of this, sophisticated physics models are being applied to ever more realistic and detailed situations, so that it is no longer necessary to restrict computer studies to highly idealized depictions of beam dynamics questions. This presentation will illustrate the application of a number of collective beam dynamics models to a range of accelerator physics problems in high intensity proton rings. In particular, we will consider the effects of space charge, transverse and longitudinal impedances, and electron cloud formation on beam parameters, stability, halo formation, collimation and losses, and possible equilibrium configurations. Examples will be taken from PSR, the CERN PS Ring, and SNS.
	Video of talk
	Transparencies
WEPLT168	ORBIT Benchmark of Space-charge-induced Emittance Growth in the CERN PS	2218
	S.M. Cousineau, J.A. Holmes ORNL/SNS, Oak Ridge, Tennessee E. Métral CERN, Geneva
	Particle tracking codes provide an invaluable tool in the design and operation of high intensity machines. An important task in the development of these codes is the validation of the space charge models through benchmark with experimental data. Presented here are benchmarks of the ORBIT particle tracking code with recent measurements of space-charge-induced transverse emittance growth in the CERN PS machine. Benchmarks of two experimental data sets are performed: Integer resonance crossing, and Montague resonance crossing.
WEPLT169	Benchmark and Threshold Analysis of Longitudinal Microwave Instability in the PSR	2221
	S.M. Cousineau, J.A. Holmes ORNL/SNS, Oak Ridge, Tennessee C. Beltran, R.J. Macek LANL/LANSCE, Los Alamos, New Mexico
	A set of inductive inserts used to provide passive longitudinal space charge compensation in the Los Alamos Proton Storage Ring cause a strong microwave instability in the beam when the inductors are at room temperature. We use the ORBIT code to perform benchmarks of the microwave instability dynamics, including the mode spectrum and the instability growth time. Additionally, we analyze the experimental instability intensity threshold and compare it with the simulated threshold. For all parameters benchmarked, results of simulations are in good agreement with the experimental data.
WEPLT170	Injection Schemes for Self Consistent Space Charge Distributions	2224
	V.V. Danilov, S.M. Cousineau, S. Henderson, J.A. Holmes, M. Plum ORNL/SNS, Oak Ridge, Tennessee
	This paper is based on recently found sets of self-consistent 2D and 3D time-dependent space charge distributions. A subset of these distributions can be injection-painted into an accumulator ring, such as Spallation Neutron Source Ring, to produce periodic space charge conditions. The periodic condition guarantees zero space-charge-induced halo growth and beam loss during injection. Practical aspects of such schemes are discussed, and simulations of a few specific cases are presented.