Coulomb interaction-induced jitter amplification in RF-compressed high-brightness electron source ultrafast electron diffraction

AbstractUltrafast electron diffraction (UED) enables studies of structural dynamics at atomic length and timescales, i.e., 0.1 nm and 0.1 ps, in single-shot mode. At present UED experiments are based on femtosecond laser photoemission from solid state cathodes. These photoemission sources perform excellently, but are not sufficiently bright for single-shot studies of, for example, biomolecular samples. We propose a new type of electron source, based on near-threshold photoionization of a laser-cooled and trapped atomic gas. The electron temperature of these sources can be as low as 10 K, implying an increase in brightness by orders of magnitude. We investigate a setup consisting of an ultracold electron source and standard radio-frequency acceleration techniques by GPT tracking simulations. The simulations use realistic fields and include all pairwise Coulomb interactions. We show that in this setup 120 keV, 0.1 pC electron bunches can be produced with a longitudinal emittance sufficiently small for enabling sub-100 fs bunch lengths at 1% relative energy spread. A transverse root-mean-square normalized emittance of εx = 10 nm is obtained, significantly better than from photoemission sources. Correlations in transverse phase-space indicate that the transverse emittance can be improved even further, enabling single-shot studies of biomolecular samples.

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An Ultracold Electron Source for Ultrafast Electron Diffraction Experiments

Research in Optical Sciences ◽

10.1364/icusd.2012.iw1d.7 ◽

2012 ◽

Author(s):

Wouter Engelen ◽

Nicola Debernardi ◽

Edgar Vredenbregt ◽

Jom Luiten

Keyword(s):

Electron Diffraction ◽

Electron Source ◽

Ultrafast Electron Diffraction

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Point-to-point Coulomb effects in high brightness photoelectron beam lines for ultrafast electron diffraction

Physical Review Accelerators and Beams ◽

10.1103/physrevaccelbeams.24.084202 ◽

2021 ◽

Vol 24 (8) ◽

Author(s):

M. Gordon ◽

S. B. van der Geer ◽

J. Maxson ◽

Y.-K. Kim

Keyword(s):

Electron Diffraction ◽

Ultrafast Electron Diffraction ◽

High Brightness ◽

Coulomb Effects ◽

Point To Point

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Coherent Electron Source for Ultrafast Electron Diffraction and Imaging

EPJ Web of Conferences ◽

10.1051/epjconf/20134110007 ◽

2013 ◽

Vol 41 ◽

pp. 10007

Author(s):

M. Müller ◽

A. Paarmann ◽

C. Xu ◽

R. Ernstorfer

Keyword(s):

Electron Diffraction ◽

Electron Source ◽

Ultrafast Electron Diffraction

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Optical Properties of HVEM Accelerators

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100114529 ◽

1975 ◽

Vol 33 ◽

pp. 180-181

Author(s):

A. Strojnik ◽

J.W. Scholl ◽

V. Bevc

Keyword(s):

Optical Properties ◽

Electron Accelerator ◽

Systematic Investigation ◽

Electron Source ◽

High Brightness ◽

The Past ◽

Wide Range ◽

Optical Behavior

The electron accelerator, as inserted between the electron source (injector) and the imaging column of the HVEM, is usually a strong lens and should be optimized in order to ensure high brightness over a wide range of accelerating voltages and illuminating conditions. This is especially true in the case of the STEM where the brightness directly determines the highest resolution attainable. In the past, the optical behavior of accelerators was usually determined for a particular configuration. During the development of the accelerator for the Arizona 1 MEV STEM, systematic investigation was made of the major optical properties for a variety of electrode configurations, number of stages N, accelerating voltages, 1 and 10 MEV, and a range of injection voltages ϕ0 = 1, 3, 10, 30, 100, 300 kV).

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A comparative study on the cold type and thermal type field emission guns used in the same electron microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100107435 ◽

1978 ◽

Vol 36 (1) ◽

pp. 58-59

Author(s):

M. Iwatsuki ◽

Y. Kokubo ◽

Y. Harada

Keyword(s):

Electron Microscope ◽

Field Emission ◽

Signal To Noise Ratio ◽

Electron Source ◽

Resolving Power ◽

Optical Source ◽

Experimental Conditions ◽

High Brightness ◽

Illumination System ◽

Transmission Electron

On accout of its high brightness, small optical source size, and minimal energy spread, the field emission gun (FEG) has the advantage that it provides the conventional transmission electron microscope (TEM) with a highly coherent illumination system and directly improves the resolving power and signal-to-noise ratio of the scanning electron microscope (SEM). The FEG is generally classified into two types; the cold field emission (C-FEG) and thermal field emission gun (T-FEG). The former, in which a field emitter is used at the room temperature, was successfully developed as an electron source for the SEM. The latter, in which the emitter is heated to the temperature range of 1000-1800°K, was also proved to be very suited as an electron source for the TEM, as well as for the SEM. Some characteristics of the two types of the FEG have been studied and reported by many authors. However, the results of the respective types have been obtained separately under different experimental conditions.

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Quantitative energy-filtered electron diffraction

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100172693 ◽

1994 ◽

Vol 52 ◽

pp. 992-993

Author(s):

R. Vincent

Keyword(s):

Electron Diffraction ◽

Inelastic Scattering ◽

Dynamic Range ◽

Electron Optics ◽

Surface Layers ◽

High Brightness ◽

Inclined Surfaces ◽

Perfect Symmetry ◽

Amorphous Surface ◽

The Ideal

Microanalysis and diffraction on a sub-nanometre scale have become practical in modern TEMs due to the high brightness of field emission sources combined with the short mean free paths associated with both elastic and inelastic scattering of incident electrons by the specimen. However, development of electron diffraction as a quantitative discipline has been limited by the absence of any generalised theory for dynamical inelastic scattering. These problems have been simplified by recent innovations, principally the introduction of spectrometers such as the Gatan imaging filter (GIF) and the Zeiss omega filter, which remove the inelastic electrons, combined with annual improvements in the speed of computer workstations and the availability of solid-state detectors with high resolution, sensitivity and dynamic range.Comparison of experimental data with dynamical calculations imposes stringent requirements on the specimen and the electron optics, even when the inelastic component has been removed. For example, no experimental CBED pattern ever has perfect symmetry, departures from the ideal being attributable to residual strain, thickness averaging, inclined surfaces, incomplete cells and amorphous surface layers.

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