Computational and experimental characterization of high-brightness beams for femtosecond electron imaging and spectroscopy
Abstract
Using a multilevel fast multipole method, coupled with the shadow imaging of femtosecond photoelectron pulses for validation, we quantitatively elucidate the photocathode, space charge, and virtual cathode physics, which fundamentally limit the spatiotemporal and spectroscopic resolution and throughput of ultrafast electron microscope (UEM) systems. We present a simple microscopic description to capture the nonlinear beam dynamics based on a two-fluid picture and elucidate an unexpected dominant role of image potential pinning in accelerating the emittance growth process. These calculations set theoretical limits on the performance of UEM systems and provide useful guides for photocathode design for high-brightness electron beam systems.
- Publication:
-
Applied Physics Letters
- Pub Date:
- December 2013
- DOI:
- 10.1063/1.4855435
- Bibcode:
- 2013ApPhL.103y3115P
- Keywords:
-
- electron microscopes;
- photocathodes;
- photoelectron spectroscopy;
- space charge;
- spatiotemporal phenomena;
- 07.81.+a;
- 07.78.+s;
- 85.60.Ha;
- Electron and ion spectrometers;
- Electron positron and ion microscopes;
- electron diffractometers;
- Photomultipliers;
- phototubes and photocathodes