No abstract

The wavelet function feedback method is proposed for controlling beam halo-chaos for high intensity proton beam in a periodic-focusing channel.After control for four different primary proton distributions,the halo intensity factor become zero,other statistical physical quantities (such as rrms and P2av) and relative average emittances are more than doubly reduced.Simulation results show that the method is very effective and has its prospect for application.

A new method for control chaos based on delay feedback of system variables is proposed. The control results of three typical chaotic systems are given. The method of control chaos can be easily realized in physical systems, for the control price of this method is low. The mechanism of the method is also discussed based on varied of average value of Lyapunov function.

Beam halo-chaos in high-current accelerators has become a key concerned issue because it can cause excessive radioactivity from the accelerators therefore signi cantly limits their applications in industry, medicine, and national defense. Some general engineering methods for chaos control have been developed in recent years, but they generally are unsuccessful for be a mhalo-chaos suppression due to many technical constraints. Beam halo-chaos is essentially a spatiotemporal chaotic motion within a high po wer proton accelerator. In this paper, some e cient nonlinear control methods, including wavelet function feedback control as a special nonlinear control method, are proposed for controlling be a mhalo-chaos under ve kinds of the initial proton beam distributions (i.e., Kapchinsky{Vladimirsky, full Gauss, 3-sigma Gauss, water-bag, and parabola distributions) respectively. Particles-in-cell simulations show that after control of be a mhalo-chaos, the beam halo strength factor is reduced to zero, and other statistical physical quantities of beam halo-chaos are doubly reduced. The methods we developed is very e ective for suppression of proton be a mhalo-chaos in a pe r i od i cfocusing channel of accelerator. Some potential application of the be a mhalo-chaos control in experiments is nally po i n ted out.

We study an intense beam propagating through the double periodic focusing channel by the particle-core model, and obtain the beam envelope equation. According to the Poincare-Lyapunov theorem, we analyze the stability of beam envelope equation and find the beam halo. The soliton control method for controlling the beam halo-chaos is put forward based on mechanism of halo formation and strategy of controlling beam halo-chaos, and we also prove the validity of the control method, and furthermore, the feasible experimental project is given. We perform multiparticle simulation to control the halo by using the soliton controller. It is shown that our control method is effective. We also find the radial ion density changes when the ion beam is in the channel, not only the halo-chaos and its regeneration can be eliminated by using the nonlinear control method, but also the density uniformity can be found at beam's centre as long as an appropriate control method is chosen.