PAC07 - List of Sessions

TUZBAB — BDMF: Beam Dynamics and Electromagnetic Fields (26-Jun-07 16:30—18:00)

Chair: R. C. Davidson, PPPL, Princeton, New Jersey

Paper	Title	Page
TUZBAB01	Experiments on Transverse Bunch Compression on the Princeton Paul Trap Simulator Experiment	810
	E. P. Gilson M. Chung, R. C. Davidson, M. Dorf, P. Efthimion, R. M. Majeski, E. Startsev PPPL, Princeton, New Jersey
	Funding: Research supported by the U. S. Department of Energy. The Paul Trap Simulator Experiment is a compact laboratory Paul trap that simulates a long, thin charged-particle bunch coasting through a kilometers-long magnetic alternating-gradient (AG) transport system by putting the physicist in the beam's frame-of-reference. The transverse dynamics of particles in both systems are described by the same sets of equations, including all nonlinear space-charge effects. The time-dependent quadrupolar electric fields created by the confinement electrodes of a linear Paul trap correspond to the axially-dependent magnetic fields applied in the AG system. Results are presented from experiments in which the lattice period and strength are changed over the course of the experiment to transversely compress a beam with an initial depressed-tune of 0.9. Instantaneous and smooth changes are considered. Emphasis is placed on determining the conditions that minimize the emittance growth and the number of halo particles produced after the beam compression. The results of PIC simulations performed with the WARP code agree well with the experimental data. Initial results from a newly installed laser-induced fluorescence diagnostic will also be discussed.
	Slides
TUZBAB02	The Extreme Value Theory to Estimate Beam Losses in High Power Linacs	815
	R. Duperrier D. Uriot CEA, Gif-sur-Yvette
	The influence of random perturbations of high intensity accelerator elements on the beam losses is considered. This influence is analyzed with the help of the Extreme Value Theory (EVT) to allow loss estimates for a very low fraction of the beam. Many fields of modern science and engineering have to deal with events which are rare but have significant consequences. EVT is considered to provide the basis for the statistical modeling of such extremes events (extreme variations of financial market for insurance companies or extreme wind speed for electric companies). To illustrate the application of this theory to beam losses estimates, the SPIRAL2 driver is used. This 5 mA deuteron accelerator is simulated from the output of the source to the target with high resolution PIC modelisations (up to 1.3 million macro-particles) using realistic external fields.
	Slides
TUZBAB03	The University of Maryland Electron Ring (UMER) Enters a New Regime of High-Tune-Shift Rings	820
	R. A. Kishek G. Bai, B. L. Beaudoin, S. Bernal, D. W. Feldman, R. Feldman, R. B. Fiorito, T. F. Godlove, I. Haber, T. Langford, P. G. O'Shea, C. Papadopoulos, B. Quinn, M. Reiser, D. Stratakis, D. F. Sutter, J. C.T. Thangaraj, K. Tian, M. Walter, C. Wu UMD, College Park, Maryland
	Funding: This work is funded by US Dept. of Energy and by the US Dept. of Defense Office of Naval Research. Circular accelerators and storage rings have traditionally been designed with limited intensity in order to avoid resonances and instabilities. The possibility of operating a ring beyond the Laslett tune shift limit has been suggested but little tested, apart from a pioneering experiment by Maschke at the BNL AGS in the early 1980s. We have recently circulated the highest-space-charge beam in a ring to date in the University of Maryland Electron Ring (UMER), achieving a breakthrough both in the number of turns and in the amount of current propagated. At undepressed tunes of up to 7.6, the space charge in UMER is sufficient to depress the tune by nearly a factor of 2, resulting in tune shifts up to 3.6. This makes the UMER beam the most intense beam that has been propagated to date in a circular lattice. This is an exciting and promising result for future circular accelerators, and the UMER beam can now be used as a platform to study intense space charge dynamics in rings.
	Slides