Investigation of mechanism of free electron laser through spontaneous radiation spectrum

The possibility of using a parabolic refractive lens with initial X-ray free-electron laser (XFEL) pulses,i.e.without a monochromator, is analysed. It is assumed that the measurement time is longer than 0.3 fs, which is the time duration of a coherent pulse (spike). In this case one has to calculate the propagation of a monochromatic wave and then perform an integration of the intensity over the radiation spectrum. Here a general algorithm for calculating the propagation of time-dependent radiation in free space and through various objects is presented. Analytical formulae are derived describing the properties of the monochromatic beam focused by a system of one and two lenses. Computer simulations show that the European XFEL pulses can be focused with maximal efficiency,i.e.as for a monochromatic wave. This occurs even for nanofocusing lenses.

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Spontaneous radiation of an electron beam in a free‐electron laser with a quadrupole wiggler

Journal of Applied Physics ◽

10.1063/1.337295 ◽

1986 ◽

Vol 60 (5) ◽

pp. 1584-1590 ◽

Cited By ~ 30

Author(s):

B. Levush ◽

T. M. Antonsen ◽

W. M. Manheimer

Keyword(s):

Electron Beam ◽

Free Electron ◽

Free Electron Laser ◽

Spontaneous Radiation

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CHANNELING OF POSITRONS THROUGH PERIODICALLY BENT CRYSTALS: ON THE FEASIBILITY OF CRYSTALLINE UNDULATOR AND GAMMA-LASER

International Journal of Modern Physics E ◽

10.1142/s0218301304002557 ◽

2004 ◽

Vol 13 (05) ◽

pp. 867-916 ◽

Cited By ~ 51

Author(s):

A. V. KOROL ◽

A. V. SOLOV'YOV ◽

W. GREINER

Keyword(s):

Electromagnetic Radiation ◽

Free Electron ◽

Free Electron Laser ◽

Interplanar Spacing ◽

High Energy ◽

Literature Survey ◽

Stimulated Emission ◽

Spontaneous Radiation ◽

Spectral Distributions ◽

Bent Crystals

The electromagnetic radiation generated by ultra-relativistic positrons channeling in a crystalline undulator is discussed. The crystalline undulator is a crystal whose planes are bent periodically with the amplitude much larger than the interplanar spacing. Various conditions and criteria to be fulfilled for the crystalline undulator operation are established. Different methods of crystal bending are described. We present the results of numeric calculations of spectral distributions of the spontaneous radiation emitted in the crystalline undulator and discuss the possibility to create the stimulated emission in such a system in analogy with the free electron laser. A careful literature survey covering the formulation of all essential ideas in this field is given. Our investigation shows that the proposed mechanism provides an efficient source for high energy photons, which is worth studying experimentally.

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A Free Electron Laser–Photoemission Electron Microscope System (FEL–PEEM)

Surface Review and Letters ◽

10.1142/s0218625x98001596 ◽

1998 ◽

Vol 05 (06) ◽

pp. 1257-1268 ◽

Cited By ~ 53

Author(s):

H. Ade ◽

W. Yang ◽

S. L. English ◽

J. Hartman ◽

R. F. Davis ◽

...

Keyword(s):

Electron Microscope ◽

Energy Range ◽

Photon Energy ◽

Free Electron ◽

Free Electron Laser ◽

Spontaneous Radiation ◽

Laser Photoemission ◽

Emission Mode ◽

First Results ◽

Photoemission Electron

We report first results from our effort to couple a high resolution photoemission electron microscope (PEEM) to the OK-4 ultraviolet free electron laser at Duke University (OK-4/Duke UV FEL). The OK-4/Duke UV FEL is a high intensity source of tunable monochromatic photons in the 3–10 eV energy range. This tunability is unique and allows us to operate near the photoemission threshold of any samples and thus maximize sample contrast while keeping chromatic berrations in the PEEM minimal. We have recorded first images from a variety of samples using spontaneous radiation from the OK-4/ Duke UV FEL in the photon energy range of 4.0–6.5 eV. Due to different photothreshold emission from different sample areas, emission from these areas could be turned on (or off) selectively. We have also observed relative intensity reversal with changes in photon energy which are interpreted as density-of-state contrast. Usable image quality has been achieved, even though the output power of the FEL in spontaneous emission mode was several orders of magnitude lower than the anticipated full laser power. The PEEM has achieved a spatial resolution of 12 nm.

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Peak Shift of Coherent Edge Radiation Spectrum Depending on Radio Frequency Field Phase of Accelerator

Applied Sciences ◽

10.3390/app12020626 ◽

2022 ◽

Vol 12 (2) ◽

pp. 626

Author(s):

Norihiro Sei ◽

Heishun Zen ◽

Hideaki Ohgaki

Keyword(s):

Radio Frequency ◽

Free Electron ◽

Free Electron Laser ◽

Electron Bunch ◽

Radiation Spectrum ◽

Local Maximum ◽

Peak Shift ◽

Field Phase ◽

Radio Frequency Field ◽

Edge Radiation

Spectra of coherent edge radiation (CER) were observed at the S-band linac facility of Kyoto University Free Electron Laser. A local maximum was observed in the CER spectrum on-crest operation of the radio frequency (RF) field. As the phase of the RF field was shifted from the crest, the frequency of the maximum decreased, and the CER spectrum approached a spectrum of Gaussian-distributed electrons in a bunch. It was found that this strange spectrum can be explained by a model in which a satellite pulse exists around a main pulse in the electron bunch. Furthermore, it demonstrated that CER is an effective tool for monitoring the shape of the electron bunch.

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