Simulation Investigation On Controlling Beam Halo-Chaos Using The Information Of Particles In Small Regions

The dynamic equation and the dynamic trait of high-current ion beams, the main mechanism of halo-chaos formation and several main nonlinear controlling methods are summarized in the paper. For the collimation method cannot reach ideal results, and the controlling information of these methods is not operational in experiment or the source region of information is too large, so it's necessary to explore a new method to obtain the controlling information in order to realize the nonlinear controlling methods in experiment. The main research work is as follow:In chapter three, the controlling information of the logarithm-function controller is improved by using the information which comes from the small region outside the matched radius replace the information which comes from the region outside the matched radius. Based on it, the PIC procedure and the logarithm-function controller G = gln(1 -λ)[67] is adopted in the simulation study. The aim to do that is to learn the results after using the new controlling information. The reason why the source region of controlling information must be reduced is that: from the nonlinear feedback strategy is proposed in 2000, one of the controlling variable which is used commonly in simulation is the radii of ion beam, such as the rms radius, but the rms radius is hard to put into pratice; another controlling variable is particles which come from the region outside the matched radius, for the region is too large, it is inconvenience to carry it out experimentally. And the reason why the logarithm-function controller is adopted is that: the controllers such as the wavelet function controller and the delayed feedback controller which can achieved good results in simulation cannot use the variable-particles as feedback information. Five different initial distributions are studied in this method. The simulation results show that except the beam halo strength factor of initial Gaussian distribution cannot reduced to zero, other initial distribution'are reduced to zero ideally. And all statistical physical quantities such as relative emittance growth, the rms radius, the maximum radius and the root-square momentum of the ions are reduced significantly. So, the controlling goats can be achieved using the improved logarithm-function controlling method to the beams satisfied five initial distributions, especially to the initial K-V distribution beam. Further study shows that the improved logarithm-function controlling method is nothing less than other controlling methods, furthermore it has more excellent feature than other controlling methods for it's controlling information is from small regions.In chapter four, the controlling results of initial K-V distribution are studied using the improved logarithm-function controlling method when the parameters are changed, in order to learn the influence of parameters to the new method'controlling results. The reason to do this work is that the parameters are fixed in the simulation of chapter three and the values are special,...