Research On High Spatiotemporal Resolution High Energy Electron Imaging And Electron Diffraction

High spatiotemporal resolving electron imaging and electron diffraction techniques are powerful tools for observing the ultra-fast world and ultra-small world.Compared to ke V low energy electrons used in traditional transmission electron microscopy and electron diffraction,high energy electron probes generated by a photo-injector owns some special advantages,like higher brightness,much better penetrating power and shorter pulse duration,and are expected to drive high energy electron imaging and diffraction instruments with better spatiotemporal resolutions,which are expected to play a significant role in high energy density physics(HEDP)diagnostics and ultrafast science studies.The main thesis work is focused on photo-injector generated high energy,high brightness electron probe driven high spatiotemporal resolving high energy electron imaging and electron diffraction techniques and their applications.In order to improve the spatial resolution of a high energy electron radiography system for diagnosis of HEDP,we conduct first-round high energy electron radiography experiment based on our S-band photo-injector and common electromagnetic lenses composed imaging beamline.Successful radiographs of mm-level opaque thick targets are obtained using ~ 50 MeV high energy electron probes,with 4? m spatial resolution and10 ?m thickness resolution,pioneering the way to diagnostics of high energy density matter.For further improving the spatial resolution and making the electron radiography system compact,we carry out research on cascaded high energy electron radiography(CHEER)based on high-gradient permanent magnet quadrupoles.Unprecedent spatial resolution of 1.6?m is obtained with a magnification factor of about 15 in single-shot CHEER experiments.In addition,we also conduct dynamic imaging experiment of ultrashort,intense laser triggered gold mesh ablation,where three different phases are observed during the melting process,thus validating the feasibility of applying this technique to diagnostics of evolution of high energy density matters.The last part of this dissertation is on mege-voltage ultrafast electron diffraction(MeV UED).As an emerging,powerful tool for ultrafast sciences,MeV UED facility has drawn considerable interest due to its compact size and cost-effectiveness.In order to provide an excellent electron diffraction platform,we propose Tsinghua MeV UED project,carry out research on theoretical analysis,beam dynamic simulation,and prove potentials of this facility to reach 100 fs resolutions.At present,installation of this UED facility has been done and is ready for beam commissioning phase.Meanwhile,aiming at high repetition-rate UED,which is an important trend for next generation MeV UED facilities,we propose the scheme of a continuous wave mode(CW)high repetition-rate MeV UED facility based on the super-conducting Terahertz free electron laser of Chinese Academy of Engineering Physics.Thorough dynamic simulation validates the feasibilities of developing a high-repetition-rate,femtosecond-resolving MeV UED facility on base of the super-conducting THz-FEL beamline.