The Application Of High Energy Electron Radiography In High Energy Density Materials Diagnosis

High Energy Density Materials（HEDM）is normally defined as a matter in the state of deposited energy larger than 10¹¹J/cm³ or equivalently pressure higher than 1Mbar.High energy density physics（HEDP）is a multidisciplinary field that studies the structures and properties of HEDM.At present,the methods producing HEDM in laboratory include laser or heaven ion beam bombarding the target and Z-pinch driving.But there is no stable and uniform HEDM on experiment.Therefore,an ultra-fast diagnostic technique which has high spatial resolution and high-dynamic range is needed to get the internal characteristics and evolution information of HEDM.The high energy ultra-short electron pulse generated by the electron LINAC based on the photocathode microwave electron gun can maintain that the sample is quasi-static during the electron beam passing through,and can be used for ultra-fast diagnosis of HEDM.This paper reports some experimental and simulated results of the high energy electron radiography（HEER）diagnosis for thin targets,ICF targets,and high-Z thick targets.The simulation results of HEER for aluminum step specimen with 7²24microns thickness and inertial confinement fusion（ICF）target show that HEER has several microns spatial resolution and high-dynamic range.Further simulations show that for single-element media,HEER can diagnose the atomic number areal density of the sample well.This conclusion is independent on the isotope doping ratio and sample density.For the high-Z large-scale samples which involved in the heavy intense heavy ion beam driving,simulated results show that the traditional HEER design is no longer suitable.In order to meet the diagnostic requirements of high-Z thick targets,the energy filtration radiography was proposed in this paper.The simulation of HEER for tungsten step sample with a thickness of 1.5 to 4 mm was carried out.Tens of microns spatial resolution got in the simulation shows that energy filtration radiography can be used for high Z thick target diagnosis.Using the energy filtration radiography,the dynamic diagnosis simulation of the warm dense matter（WDM）generated by the HIAF heavy ion beam driving can clearly show the evolution of the sample.The ultra-short pulses generated by the electron linear accelerator are the indemnification for ultra-fast diagnosis.In cooperation with Tsinghua University,the Institute of Modern Physics carried out HEER experiments on TTX experimental platform.The experimental results indicate that the HEER has high-dynamic range for thickness from 7μm to 800μm or areal density from 1.9mg/cm² to 0.188g/cm² for low Z sample.And the several microns spatial resolution is also got on experiment.The spatial resolution and thickness-transmittance curve are in good agreement with simulations by comparing the experimental and simulated results for aluminum step target.In addition,for the dark field radiography phenomenon observed on experiment,the simulation and optimized scheme are carried out in this paper.The results show that the dark field radiography has better density resolution for thin target and has several microns spatial resolution.It has potential application value in the diagnosis of HEDM.In summary,HEER can achieve microns spatial resolution for weak bremsstrahlung system diagnosis and tens microns for strong bremsstrahlung systems diagnosis and have high-dynamic range for both and weak bremsstrahlung.Therefore,HEER is expected to be applied to the diagnosis of HEDM.