Abstract
Transition radiation generated from a relativistic electron beam is used as a tool for diagnostics of the beam. Also, it can be used as a source of femtosecond (fs) THz radiation. We are generating the THz radiation with the pulse energy of $3\text{ }\text{ }\ensuremath{\mu}\mathrm{J}$ by means of the coherent transition radiation (CTR) from 55-MeV electron beam in the fs-THz linac at the Pohang Accelerator Laboratory. The spatial distribution of CTR could be easily observed by using a pyroelectric camera. In this paper, we report observation of the transversal distribution of CTR in the prewave zone, and compare with calculated results based on the bunch form factor.
Highlights
A fs-THz linac was constructed to generate femtosecond THz radiation by using an ultrashort electron beam at the Pohang Accelerator Laboratory (PAL) [1,2]
We supposed that the complication comes from the electron beam with a nonuniform transverse distribution, and the equations were derived using Casalbuoni’s paper [19] to confirm the effect of the transverse beam distribution on the spatial distribution of coherent transition radiation (CTR) [20]: d2U d!d
From the calculation of the peak-intensity angle using the bunch form factors of the electron bunch generated in the fs-THz linac, we ascertained that the angle agrees with the one found from the CTR image taken by a pyroelectric camera
Summary
A fs-THz linac was constructed to generate femtosecond THz radiation by using an ultrashort electron beam at the Pohang Accelerator Laboratory (PAL) [1,2]. Coherent radiation is emitted from the electron bunch whose length is shorter than the radiation wavelength. Where pð!Þ is the spectral radiation power from single electron, and fð!Þ is the bunch form factor, which is the Fourier transform of [Fðr~Þ] squared, fð!Þ the 1⁄4j. Transition radiation in the THz regime becomes coherent when it is generated from the electron bunch shorter than the THz wavelength. Transition radiation has been used for beam diagnostics, and especially coherent transition radiation (CTR) gives a great tool of diagnosing the bunch length of subpicosecond electron beam [12,13,14,15,16,17]. The observation results are compared with the theoretical results using the transverse beam distribution generated at the PAL fs-THz linac and the bunch form factor obtained from a streak camera image.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Physical Review Special Topics - Accelerators and Beams
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
