The Preliminary Research Of Imaging Diagnostic By High Energy Electron Beam

The research of high energy density is hot nowdays, and the diagnostic of highenegy density matter is an important part of HED. The original diagnostic sourceincludes proton beam, X-ray, neutron beam and electron beam. Proton imaging is themajor method of HED diagnostic. Though proton imaging has high space resolution andability to resolve areal density, the system is large, and to create hundreds of MeVproton needs long accelerating cavity, it costs high. And the imaging experiment basedon the electron can have more compact equipment. The electron imaging is widely usedin electron microscopy, the energy is between tens of keV to MeV, and the thick ofsample is small. The electron imaging experiment we will start uses electron beam ofenergy up to tens of MeV, and it can image the sample of thicker and higher density.The electron has a certain angular distribution after reacting with matter. Thephysical foundation of electron imaging is electron will have different angulardistribution after reacting with different areal density and different material. We chooseMCNP and Geant4to simulate the Monte Carlo simulation of electron reacting withmatter. And finally we select Geant4as the software we use in the simulationafterwards.To electron diagnostic, the design of electron optic destruction to achievepoint-to-point imaging in transmission system is important. And the transport processneeds quadruplets to focus and defocus electron. We need to make the image aberrationsmallest in the image plane. As the electron has enegy spread, the chromatic aberrationis an important parameter in the design. To reduce chromatic aberration, we usematching lens system to couple the phase space of electron in the sample plane.Otherwise, we add a collimator to select the angle that the particle reacting with thesample for multiple coulomb scattering. By straining off the large angle particles,wecould make the result of image reflect the information of the sample.In the simulation of imaging, we achieve high space resolution and the ability toresolve areal density. It shows that as a new diagnostic method, electron imaging hascompetitive strength.