Simulation On Radiography By A Laser-accelerated Electron Beam

The laser-plasma interactions and related processes are extremely complex, and various methods and techniques have been used to get physical information and parameters from these interactions, but each diagnostic has its limitations. With the development of the laser technology, people have begun to use laser-accelerated charged particle beams to study plasma or other substances by radiography. Using proton beam to diagnose laser plasma has been reported many times, but the generation of high-energy proton beam is still very difficult. By contrast, the generation of high-energy electron beam is not only relatively easy, but the generated electron beam has a shorter pulse width. If electron beams are applied to radiography, it would achieve greater penetration depth and faster time resolution.In this paper, by Fluka which is a Monte Carlo simulation program(2011edition), electron beam radiography is simulated in detail. Starting from Moliere multiple scattering theory, First, a nonuniform thick carbon target is simulated by a collimated electron beam in order to study the sensitivity of electron beam for the change of target thickness, and the results show that when the incident electron range is close to the target thickness, the electron beam can diagnose target surface of small nonuniformity till3%o. In comparision, it is found that a proton beam is advantageous to diagnose the nonuniformity. Secondly, a segmented carbon target with a1%density difference is radiographied by collimated100-MeV electron and proton beams, and the results indicate that100-MeV electron and proton beam can both diagnose a1%density difference thick carbon target interface with comparable contrast. Thirdly, a modelled inertial-confinement-fusion (ICF) target is irradiated by a point-like electron beam, and the results show200MeV electron beam can achieve a better contrast. Fourthly, based on the marginal range energy, a nonuniform thin target is simulated by a collimated160-keV electron beam. These results indicate that the radiography by laser-accelerated electron beams can diagnose thick target surface nonuniformity, distinguish small density difference interface and the ICF fusion pellet interface, and diagnose thin target surface roughness.Finally, a Matlab program has been written to calculate electron beam’s deflection in the laser plasma generated magnetic field, and the result is consistent with Fluka simulation result. Then the program is used to calculate electron beam movement in magnetic reconnection, and the preliminary results show that the electron beam can be used to diagnose the magnetic reconnection phenomena.