| In this paper,the transport of high energy proton beam in dense plasma is studied based on Lapins code,which is used to study the interaction between high energy ion and dense plasma.We mainly study the interaction between high energy proton beam with 1GeV kinetic energy and background plasma.In the short-distance propagation,the proton beam appears self-focusing phenomenon,and in the long-distance propagation,there is a new twist jitter phenomenon.Focusing phenomenon has been found in simulation and experiment at home and abroad,and has a good theoretical explanation.The self-focusing force of the proton beam will increase with the increase of the density of the proton beam,and even the phenomenon of multiple focusing can be observed.With the increase of the density ratio of the proton beam to the background plasma,the distortion of the proton beam develops rapidly.At present,it is known that most foreign codes of the same type are unable to carry out long-distance and long-time operations,so such simulation results are found on Lapins code for the first time.Through the analysis of simulation data,the possibility of kink instability and bump-on-tail instability is excluded,and it is considered as hosing instability.In practical application,we provide three methods to suppress the instability.One is to suppress the instability by applying a magnetic field in the direction of propagation.However,with the increase of the ratio of ion beam density to background plasma density,it is necessary to increase the intensity of external magnetic field.The other is to increase the density of the background plasma,that is,to reduce the ratio to suppress the instability,but too large ratio will also weaken the self-focusing effect and affect the compression efficiency of the ion beam.The third is to reduce the background plasma temperature.The stable transport of high-energy ion beam in dense plasma can be realized by coordinating several ways,which has important application value. |
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