High-efficiency broadband THz emission via diffraction-radiation cavity

Yosuke Honda,Ryukou Kato,Tsukasa Miyajima,Miho Shimada,Naoto Yamamoto,Ryota Takai,Alexander Aryshev,Takashi Uchiyama,Takashi Obina

doi:10.1103/physrevaccelbeams.22.040703

Yosuke Honda, Ryukou Kato + Show 7 more

Open Access

https://doi.org/10.1103/physrevaccelbeams.22.040703

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Abstract

Accelerator-based terahertz (THz) radiation has been expected to realize a high-power broadband source. Employing a low-emittance and short-bunch electron beam at a high repetition rate, a scheme of coherent diffraction-radiation in an optical cavity layout is proposed. The scheme's stimulated radiation process between bunches can greatly enhance the efficiency of the radiation emission. We performed an experiment with a superconducting linac constructed as an energy recovery linac (ERL) test facility. The electron beam passes through small holes in the cavity mirrors without being destroyed. A sharp THz resonance signal, which indicates broadband stimulated radiation correlated with beam deceleration, was observed while scanning the round-trip length of the cavity. This observation proves the efficient beam-to-radiation energy conversion due to the stimulated radiation process.

Highlights

Light sources have played important roles in the progress of science in various fields
We present an experiment performed with a modern superconducting linac constructed as a test facility of an energy recovery linac (ERL) [29]
A scheme based on the Coherent diffraction radiation (CDR) layout is attractive, because the layout is easy to install in a straight section, it does not destroy the electron beam, and it may be compatible with a high-power electron beam, such as the one in an ERL

Summary

Introduction

Light sources have played important roles in the progress of science in various fields. THz light sources are the most immature over a wide spectrum of light. As it corresponds to a photon energy of 1.2 to 12 meV and a temperature of 14 to 140 K, the natural environment at room temperature is filled with THz-scale phenomena. The excitation energy of molecular dynamics, such as the rotation and oscillation of a molecule and lattice, corresponds to the THz scale. Development of THz sources is necessary for investigating such dynamics. For the production of high-power radiation, the efficiency of THz radiation production is the key for the source development

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