Beam halo-chaos in high-current accelerators has become a key concerned issue because it can cause excessive radioactivity from the accelerators therefore significantly limits their applications in industry,medicine,a...Beam halo-chaos in high-current accelerators has become a key concerned issue because it can cause excessive radioactivity from the accelerators therefore significantly 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 beam halo-chaos suppression due to many technical constraints.Beam halo-chaos is essentially a spatiotemporal chaotic motion within a high power proton accelerator.In this paper,some efficient nonlinear control methods,including wavelet function feedback control as a special nonlinear control method,are proposed for controlling beam halo-chaos under five 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 beam halo-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 effective for suppression of proton beam halo-chaos in a periodic focusing channel of accelerator.Some potential application of the beam halo-chaos control in experiments is finally pointed out.展开更多
A robust output-feedback controller is designed by using observer plus backstepping procedure to solve the tracking problems of a class of nonlinear uncertain systems. To make the design procedure and the controller s...A robust output-feedback controller is designed by using observer plus backstepping procedure to solve the tracking problems of a class of nonlinear uncertain systems. To make the design procedure and the controller structure simple, three techniques are applied: ① Only a linear observer is constructed to estimate the unknown states; ② A normalization signal is introduced. ③ A positive nonlinear function used to generate the normalization signal and a group of positive nonlinear functions used in the nonlinear damping terms are all chosen properly. The assumption made on the reference signals is much weaker than existing schemes, therefore the designed controller can be applied to track much broader classes of reference signals. The global boundness of all closed-loop signals can be guaranteed and the output tracking error can be made as small as possible if the design constants are chosen large enough.展开更多
文摘Beam halo-chaos in high-current accelerators has become a key concerned issue because it can cause excessive radioactivity from the accelerators therefore significantly 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 beam halo-chaos suppression due to many technical constraints.Beam halo-chaos is essentially a spatiotemporal chaotic motion within a high power proton accelerator.In this paper,some efficient nonlinear control methods,including wavelet function feedback control as a special nonlinear control method,are proposed for controlling beam halo-chaos under five 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 beam halo-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 effective for suppression of proton beam halo-chaos in a periodic focusing channel of accelerator.Some potential application of the beam halo-chaos control in experiments is finally pointed out.
文摘A robust output-feedback controller is designed by using observer plus backstepping procedure to solve the tracking problems of a class of nonlinear uncertain systems. To make the design procedure and the controller structure simple, three techniques are applied: ① Only a linear observer is constructed to estimate the unknown states; ② A normalization signal is introduced. ③ A positive nonlinear function used to generate the normalization signal and a group of positive nonlinear functions used in the nonlinear damping terms are all chosen properly. The assumption made on the reference signals is much weaker than existing schemes, therefore the designed controller can be applied to track much broader classes of reference signals. The global boundness of all closed-loop signals can be guaranteed and the output tracking error can be made as small as possible if the design constants are chosen large enough.
