Communication: Effects of thermionic-gun parameters on operating modes in ultrafast electron microscopy.

Erik Kieft,Pranav K Suri,David J Flannigan,Karl B Schliep

doi:10.1063/1.4930174

Erik Kieft, Pranav K Suri + Show 2 more

Open Access

https://doi.org/10.1063/1.4930174

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Abstract

Ultrafast electron microscopes with thermionic guns and LaB6 sources can be operated in both the nanosecond, single-shot and femtosecond, single-electron modes. This has been demonstrated with conventional Wehnelt electrodes and absent any applied bias. Here, by conducting simulations using the General Particle Tracer code, we define the electron-gun parameter space within which various modes may be optimized. The properties of interest include electron collection efficiency, temporal and energy spreads, and effects of laser-pulse duration incident on the LaB6 source. We find that collection efficiencies can reach 100% for all modes, despite there being no bias applied to the electrode.

Highlights

Ultrafast electron microscopes with thermionic guns and LaB6 sources can be operated in both the nanosecond, single-shot and femtosecond, single-electron modes
With ultrafast electron microscopy (UEM), the millisecond temporal resolutions typically accessible with conventional transmission electron microscopes (TEMs) and compatible digital detectors can be extended to the femtosecond timescale
The TEM platform upon which the first-generation fs UEM was based is an FEI Tecnai 120 kV instrument equipped with a self-biasing thermionic electron gun (TEG) and LaB6 emission source

Summary

Introduction

Ultrafast electron microscopes with thermionic guns and LaB6 sources can be operated in both the nanosecond, single-shot and femtosecond, single-electron modes.

Results

Conclusion