High quality single shot ultrafast MeV electron diffraction from a photocathode radio-frequency gun

Fu, Feichao; Liu, Shengguang; Zhu, Ping; Xiang, Dao; Zhang, Jie; Cao, Jianming

doi:10.1063/1.4892135

Cited by 62 publications

(39 citation statements)

References 15 publications

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“…10,26,[28][29][30][31][32][33][34][35][36][37] Photoinjectors were originally optimized for operating at 100s of pC or higher bunch charge, while for MeV UED purposes, a few pC or lower per pulse is preferred. A series of new techniques for the generation, control, and characterization of low charge high brightness electron beams has been developed.…”

Section: Introductionmentioning

confidence: 99%

Mega-electron-volt ultrafast electron diffraction at SLAC National Accelerator Laboratory

Weathersby

Brown

Centurion

et al. 2015

Review of Scientific Instruments

381

251

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Ultrafast electron probes are powerful tools, complementary to x-ray free-electron lasers, used to study structural dynamics in material, chemical, and biological sciences. High brightness, relativistic electron beams with femtosecond pulse duration can resolve details of the dynamic processes on atomic time and length scales. SLAC National Accelerator Laboratory recently launched the Ultrafast Electron Diffraction (UED) and microscopy Initiative aiming at developing the next generation ultrafast electron scattering instruments. As the first stage of the Initiative, a mega-electron-volt (MeV) UED system has been constructed and commissioned to serve ultrafast science experiments and instrumentation development. The system operates at 120-Hz repetition rate with outstanding performance. In this paper, we report on the SLAC MeV UED system and its performance, including the reciprocal space resolution, temporal resolution, and machine stability. C 2015 AIP Publishing LLC. [http://dx

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Section: Introductionmentioning

confidence: 99%

Mega-electron-volt ultrafast electron diffraction at SLAC National Accelerator Laboratory

Weathersby

Brown

Centurion

et al. 2015

Review of Scientific Instruments

381

251

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“…Therefore, the performance of UED can be tremendously improved by using electrons from high brightness MeV electron source, e.g., radio-frequency (rf) photoinjectors [21][22] . Over the past decades, the number of MeV UED instruments has been growing rapidly [23][24][25][26][27][28][29][30] , which provides an excellent opportunity to achieve femtosecond electron microdiffraction. In this Letter, we report on the experimental demonstration of femtosecond MeV electron microdiffraction from the SLAC UED instrument 30 .…”

mentioning

confidence: 99%

Femtosecond mega-electron-volt electron microdiffraction

Shen

Lundström

et al. 2018

Ultramicroscopy

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Instruments to visualize transient structural changes of inhomogeneous materials on the nanometer scale with atomic spatial and temporal resolution are demanded to advance materials science, bioscience, and fusion sciences. One such technique is femtosecond electron microdiffraction, in which a short pulse of electrons with femtosecondscale duration is focused into a micron-scale spot and used to obtain diffraction images to resolve ultrafast structural dynamics over localized crystalline domain. In this letter, we report the experimental demonstration of time-resolved mega-electron-volt electron microdiffraction which achieves a 5 μm root-mean-square (rms) beam size on the sample and a 100 fs rms temporal resolution. Using pulses of 10k electrons at 4.2 MeV energy with a normalized emittance 3 nm-rad, we obtained high quality diffraction from a single 10 μm paraffin ( ) crystal. The phonon softening mode in optical-pumped polycrystalline Bi was also time-resolved, demonstrating the temporal resolution limits of our instrument design. This new characterization capability will open many research opportunities in material and biological sciences.Time-resolved x-ray 1-3 and electron microbeams 4-6 are emerging tools with broad applications in science and technology. Achieving high temporal resolving power provides insight into structural dynamics of materials in non-equilibrium states for understanding and controlling of energy and matter 7 . Delivering a focused, micron-scale beam to a sample under study is of paramount importance, as it enables the study of samples that cannot be prepared at the macroscale, or are intrinsically inhomogeneous. For example, the lateral size of a "large" protein crystal is typically less than 100 μm. Further, small protein crystals almost always exhibit greater perfection and less impurity than large crystals 8 . Matching the beam size to that of the small protein crystal sample provides the best signal-to-noise (SNR) ratio for crystallography. The inhomogeneous nature of natural and nanoscale materials also requires micron-scale probes to determine local composition, chemistry, and crystalline structure. With the advent of high brightness x-ray free-electron lasers and efficient x-ray focusing optics, x-ray microbeams with femtosecond level temporal resolving power have been achieved [9][10][11][12] . Extensive research and development efforts are underway to push the frontier of electron microbeams towards the femtosecond time scales temporal resolution in the Ultrafast Electron Diffraction (UED).Electron microdiffraction with continuous wave beams is a well-established technique in conventional transmission electron microscopy (TEM) 13 . Recently, ultrafast electron microscopy has been built by modifying a conventional TEM from thermionic or field emission electron sources to ultrafast laser-excited photoemission electron sources [14][15] , allowing timeresolved optical pump -electron probe experiments. Dedicated kilo-electron-volt (keV) ultrafast electron diffraction machines ha...

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“…We propose to conduct a proof-of-principle experiment to test this novel scheme for the generation of a single-cycle radiation pulse at Shanghai Jiao Tong University where a photocathode rf gun is available [23] . The electron beam energy at the exit of the photocathode rf gun is about 3.3 MeV.…”

Section: Proposed Experimentsmentioning

confidence: 99%

Generating quasi-single-cycle THz pulse from frequency-chirped electron bunch train and a tapered undulator

Wang

et al. 2016

High Pow Laser Sci Eng

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We propose a proof-of-principle experiment to test a new scheme to produce a single-cycle radiation pulse in freeelectron lasers (FELs). Here, a few α-BBO crystals will be first used to produce an equally spaced laser pulse train. Then, the laser pulse train illuminates the cathode to produce a frequency-chirped electron bunch train in a photocathode rf gun. Finally, the frequency-chirped electron bunch train passes through a tapered undulator to produce a quasi-singlecycle THz pulse. This experiment should allow comparison and confirmation of predictive models and scaling laws, and the preliminary experimental results will also be discussed.

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High quality single shot ultrafast MeV electron diffraction from a photocathode radio-frequency gun

Cited by 62 publications

References 15 publications

Mega-electron-volt ultrafast electron diffraction at SLAC National Accelerator Laboratory

Mega-electron-volt ultrafast electron diffraction at SLAC National Accelerator Laboratory

Femtosecond mega-electron-volt electron microdiffraction

Generating quasi-single-cycle THz pulse from frequency-chirped electron bunch train and a tapered undulator

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