Proton Imaging Of The Relativistic Laser-produced Near-critical-density Plasma

With the development of the technology,the interaction between laser and near-critical-density plasma has become one of the hottest research fields and has received extensive attention.In this thesis,the kinetics of the interaction between intense laser and near-critical-density plasma is studied by proton radiography.The following are the main contents of the thesis:The first part consists of the first two chapters,which are the basic introduction to the research works in this thesis.The first chapter introduces the basic concepts related to this thesis and the background of this research,including: the development of relativistic laser technology,basic plasma theory,the process of laser-plasma interaction,recent development of near-critical density plasma,and proton radiography technology.The second chapter introduces the experimental system of the Laser Plasma Laboratory of Shanghai Jiao Tong University,including: 200 TW laser system,target area system,high-density gas target system,detectors and common diagnosis.The second part introduces research works during my master's career,which consists of Chapter Three to Chapter Five.The third chapter introduces the proton detection system based on real-time diagnosis.The system was designed by myself and is suitable for the target chamber system of Shanghai Jiao Tong University.Using the scintillator as a detector,real-time diagnosis of the generated proton signal can be performed in the experiments with high repetition rate.Compared with the conventional RCF stack detector,it has the advantages of convenient operation,high flexibility and real-time detection.The detection system can work well and be applied in subsequent experiments.The fourth chapter introduces the experimental research of the interaction between laser and near-critical density plasma in Shanghai Jiao Tong University.In the experiment,a cavity structure and filament evolution of the plasma were observed by optical shadowgraph images.The proton photograph was used to see the deflection of the proton beam by the internal electric field of the plasma,and the magnitude of the electric field and its time evolution were calculated with the experimental results.The fifth chapter introduces the further experimental research carried out on the XG III device.The proton probe with wide spectrum is used to see the structure inside the black cavity in the previous optical shadowgraph images.Then we try to use the laser interaction with ablation shaped near-critical-density plasma to produce ion acceleration.In the experiment,the energy of the accelerated helium ions is about 2 MeV.The third part is the sixth chapter,which is a summary of the research work of this thesis and the prospect of future experimental research.