Streak camera measurements of electron bunch length from a copper photocathode in an RF gun

A magnetic chicane bunch compressor for a new compact accelerator-based terahertz (THz) radiation source at the Institute of Advanced Energy, Kyoto University, was completely installed in March 2016. The chicane is employed to compress an electron bunch with an energy of 4.6 MeV generated by a 1.6-cell photocathode radio frequency (RF)-gun. The compressed bunch is injected into a short planar undulator for THz generation by coherent undulator radiation (CUR). The characteristics of the bunch compressor and the compressed bunch were investigated by observing the coherent transition radiation (CTR). The CTR spectra, which were analyzed by using a Michelson interferometer, and the compressed bunch length were also estimated. The results were that the chicane could compress the electron bunch at a laser injection phase less than 45 degrees, and the maximum CTR intensity was observed at a laser injection phase around 24 degrees. The optimum value of the first momentum compaction factor was around −45 mm, which provided an estimated rms bunch length less than 1 ps.

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Electron bunch length monitors using spatially encoded electro-optical technique in an orthogonal configuration

Applied Physics Letters ◽

10.1063/1.3266919 ◽

2009 ◽

Vol 95 (23) ◽

pp. 231106 ◽

Cited By ~ 6

Author(s):

X. Yang ◽

T. Tsang ◽

T. Rao ◽

J. B. Murphy ◽

Y. Shen ◽

...

Keyword(s):

Electron Bunch ◽

Bunch Length ◽

Optical Technique

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Radiation Production Using Femtosecond Electron Bunches

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.107.11 ◽

2005 ◽

Vol 107 ◽

pp. 11-14

Author(s):

C. Thongbai ◽

V. Jinamoon ◽

N. Kangrang ◽

K. Kusoljariyakul ◽

S. Rimjaem ◽

...

Keyword(s):

Far Infrared ◽

Bunch Length ◽

X Rays ◽

Research Facility ◽

X Ray ◽

Electron Bunches ◽

Rf Gun ◽

Intense Radiation ◽

Far Infrared Radiation ◽

Femtosecond Electron Bunches

Femtosecond electron bunches can be generated from a system consisting of an RF gun with a thermionic cathode, an alpha magnet, and a linear accelerator and can be used to produce femtosecond (fs) electromagnetic radiation pulses. At the Fast Neutron Research Facility (FNRF), Thailand, we are especially interested in production in Far-infrared (FIR) and x-radiation. In the far-infrared, radiation is emitted coherently for wavelengths which are longer than the electron bunch length, yielding intense radiation. Although, the x-rays emitted are incoherent, its femtosecond time scale is crucial for development of a femtosecond x-ray source.

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Manipulation of Laser Distribution to Mitigate the Space-Charge Effect for Improving the Performance of a THz Coherent Undulator Radiation Source

Particles ◽

10.3390/particles1010018 ◽

2018 ◽

Vol 1 (1) ◽

pp. 238-252 ◽

Cited By ~ 1

Author(s):

Siriwan Krainara ◽

Shuya Chatani ◽

Heishun Zen ◽

Toshiteru Kii ◽

Hideaki Ohgaki

Keyword(s):

Electron Beam ◽

Space Charge ◽

Electron Bunch ◽

Beam Quality ◽

Space Charge Effect ◽

Bunch Length ◽

Charge Effect ◽

Simulation Code ◽

Undulator Radiation ◽

Radiated Power

A THz coherent undulator radiation (THz-CUR) source has been developed at the Institute of Advanced Energy, Kyoto University. A photocathode Radio-Frequency (RF) gun and a bunch compressor chicane are used for generating short-bunch electron beams. When the electron beam energy is low, the space-charge effect strongly degrades the beam quality, such as the bunch length and the energy spread at the high bunch charge condition at around 160 pC, and results in the reduction of the highest frequency and the maximum radiated power of the THz-CUR. To mitigate the space charge effect, we have investigated the dependence of the electron beam quality on the laser distribution in transverse and longitudinal directions by using a numerical simulation code, General Particle Tracer GPT. The manipulation of the laser distribution has potential for improving the performance of the THz-CUR source. The electron bunch was effectively compressed with the chicane magnet when the laser transverse distribution was the truncated Gaussian profile, illuminating a cathode. Moreover, the compressed electron bunch was shortened by enlarging the laser pulse width. Consequently, an enhancement of the radiated power of the THz-CUR has been indicated.

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