Discrete Dynamics in Nature and Society
Volume 7 (2002), Issue 3, Pages 165-175

Controlling halo-chaos via wavelet-based feedback

Jin-Qing Fang,1 Guanrong Chen,2 and Geng Zhao1

1China Institute of Atomic Energy, P.O. Box 275-27, Beijing 102413, China
2Department of Electronic Engineering, City University of Hong Kong, Hong Kong, China

Received 14 May 2001

Copyright © 2002 Jin-Qing Fang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Halo-chaos in high-current accelerator has become one of the key issues because it can cause excessive radioactivity from the accelerators and significantly limits the applications of the new accelerators in industrial and other fields. Some general engineering methods for chaos control have been developed, but they generally are unsuccessful for halo-chaos suppression due to many technical constraints. In this article, controllability condition for beam halo-chaos is analyzed qualitatively. Then Particles-in-Cell (PIC) simulations explore the nature of beam halo-chaos formation. A nonlinear control method and wavelet function feedback controller are proposed for controlling beam halo-chaos. After control of beam halo-chaos for initial proton beam with water bag distributions, the beam halo strength factor H is reduced to zero, and other statistical physical quantities of beam halo-chaos are doubly reduced. The results show that the developed methods in this paper are very effective for proton beam halo-chaos suppression. Potential application of the halo-chaos control method is finally pointed out.