Demonstration of transmission high energy electron microscopy

Abstract

High energy electrons have been used to investigate an extension of transmission electron microscopy. This technique, transmission high energy electron microscopy (THEEM), provides two additional capabilities to electron microscopy. First, high energy electrons are more penetrating than low energy electrons, and thus, they are able to image through thicker samples. Second, the accelerating mode of a radio-frequency linear accelerator provides fast exposures, down to 1 ps, which are ideal for flash radiography, making THEEM well suited to study the evolution of fast material processes under dynamic conditions. Initial investigations with static objects and during material processing have been performed to investigate the capabilities of this technique.

Ultrafast High-Energy Electron Radiography Application in Magnetic Field Delicate Structure Measurement

“…Relativistic speed beams are taken easily by making the electrons penetrate specimen with millimeter size in several tens of picoseconds; compared with the other relativistic particles, electron has lower magnetic rigidity, which makes it more sensitive to the electromagnetic field; besides, ultrashort bunch is taken easier, to ensure the quasistatic of diagnosed specimen. High-energy electron radiography (HEER) has been developed at LANL, Tsinghua University and Institute of Modern Physics, Chinese Academy of Science, in the past several years [20][21][22][23][24][25][26]. The several microns spatial resolution has been also taken in the experiment.…”

Direct Imaging with Hundreds of MeV Electron Bunches from Laser Wakefield Acceleration

“…[ 11–15 ] Recently, a dynamics image for melting and freezing process of alloy (Bi 80 Sn 20 ) using 14 GeV electron beam with an 8.8 μm resolution has been achieved at Stanford Linear Accelerator Center (SLAC) through transmission high energy electron microscopy (THEEM). [ 12 ] The entire dynamics process is monitored for a half hour at ≈5 Hz. [ 12 ] The high energy electron beams make it easy to achieve dynamics imaging with sufficient number of electrons with ultrashort bunch duration in a single shot mode for lower space charge effect.…”

“…[ 12 ] The entire dynamics process is monitored for a half hour at ≈5 Hz. [ 12 ] The high energy electron beams make it easy to achieve dynamics imaging with sufficient number of electrons with ultrashort bunch duration in a single shot mode for lower space charge effect. [ 16 ] For thicker objects, high energy electron beams own better penetration ability and sufficient resolution within the radiation length.…”

“…[ 10 ] Efforts have been made to improve the resolution of high energy electron radiography which promote the spatial resolution from 100 μm level to sub‐micron even nanometer level and temporal resolution from nanosecond to picosecond in conventional accelerators. [ 11–15 ] Recently, a dynamics image for melting and freezing process of alloy (Bi 80 Sn 20 ) using 14 GeV electron beam with an 8.8 μm resolution has been achieved at Stanford Linear Accelerator Center (SLAC) through transmission high energy electron microscopy (THEEM). [ 12 ] The entire dynamics process is monitored for a half hour at ≈5 Hz.…”

Visualizing the melting processes in ultrashort intense laser triggered gold mesh with high energy electron radiography

“…As an alternative option to intensively studied proton radiography, high energy electron radiography (HEER) 12 has drawn considerable interest due to its potentials to provide high spatiotemporal resolution with much easier accessibility and manipulability. Recent works have improved spatial resolution of HEER to a few microns 13,14 and applied this technique to image dynamic processes 14 . However, full advantages of high energy electron probes with short pulse duration and flexibly tunable time structure have not been taken yet, and this is especially true when using high brightness electron probes generated from state-of-the-art RF photo-injectors.…”