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Title: Coherent Terahertz Radiation at UVSOR-II

Abstract

Development of intense terahertz radiation source is progressing at UVSOR-II, based on the mechanism of coherent synchrotron radiation (CSR). The terahertz CSR has successfully been produced by two methods. When the storage ring is operated in the single bunch mode with a sufficiently high beam current, intense bursts of terahertz radiation are emitted. Micro-structures in the longitudinal density distribution of the electron bunches created by a beam instability may be the origin of the radiation. The duration of the bursts is typically 100 micro-seconds. The peak intensity is 10000 times higher than that of the normal synchrotron radiation. The bursts appear chaotically or quasi-periodically depending on the beam current with a typical interval of 10 milli-seconds. It has been also demonstrated that the terahertz CSR could be produced by the laser-bunch slicing method. The density modulation produced on the electron bunch by the laser is the origin of CSR. The repetition rate of the terahertz pulses is 1 kHz, which is same as the laser repetition rate. The intensity per pulse is 105 times higher than that of the normal SR.

Authors:
; ; ; ;  [1];  [2];  [3]
  1. UVSOR, Institute for Molecular Science, Myodaij-cho, Okazaki, 444-8585 (Japan)
  2. Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603 (Japan)
  3. Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka, 590-0494 (Japan)
Publication Date:
OSTI Identifier:
21052619
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 879; Journal Issue: 1; Conference: 9. international conference on synchrotron radiation instrumentation, Daegu (Korea, Republic of), 28 May - 2 Jun 2006; Other Information: DOI: 10.1063/1.2436008; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; BEAM BUNCHING; BEAM CURRENTS; DENSITY; DISTRIBUTION; ELECTRONS; EMISSION; KHZ RANGE; LASERS; MICROSTRUCTURE; MODULATION; PERIODICITY; PHOTON BEAMS; PULSES; STORAGE RINGS; SYNCHROTRON RADIATION; SYNCHROTRON RADIATION SOURCES; THZ RANGE

Citation Formats

Katoh, Masahiro, Hosaka, Masahito, Mochihashi, Akira, Shimada, Miho, Kimura, Shin-ichi, Takashima, Yoshifumi, and Takahashi, Toshiharu. Coherent Terahertz Radiation at UVSOR-II. United States: N. p., 2007. Web. doi:10.1063/1.2436008.
Katoh, Masahiro, Hosaka, Masahito, Mochihashi, Akira, Shimada, Miho, Kimura, Shin-ichi, Takashima, Yoshifumi, & Takahashi, Toshiharu. Coherent Terahertz Radiation at UVSOR-II. United States. doi:10.1063/1.2436008.
Katoh, Masahiro, Hosaka, Masahito, Mochihashi, Akira, Shimada, Miho, Kimura, Shin-ichi, Takashima, Yoshifumi, and Takahashi, Toshiharu. Fri . "Coherent Terahertz Radiation at UVSOR-II". United States. doi:10.1063/1.2436008.
@article{osti_21052619,
title = {Coherent Terahertz Radiation at UVSOR-II},
author = {Katoh, Masahiro and Hosaka, Masahito and Mochihashi, Akira and Shimada, Miho and Kimura, Shin-ichi and Takashima, Yoshifumi and Takahashi, Toshiharu},
abstractNote = {Development of intense terahertz radiation source is progressing at UVSOR-II, based on the mechanism of coherent synchrotron radiation (CSR). The terahertz CSR has successfully been produced by two methods. When the storage ring is operated in the single bunch mode with a sufficiently high beam current, intense bursts of terahertz radiation are emitted. Micro-structures in the longitudinal density distribution of the electron bunches created by a beam instability may be the origin of the radiation. The duration of the bursts is typically 100 micro-seconds. The peak intensity is 10000 times higher than that of the normal synchrotron radiation. The bursts appear chaotically or quasi-periodically depending on the beam current with a typical interval of 10 milli-seconds. It has been also demonstrated that the terahertz CSR could be produced by the laser-bunch slicing method. The density modulation produced on the electron bunch by the laser is the origin of CSR. The repetition rate of the terahertz pulses is 1 kHz, which is same as the laser repetition rate. The intensity per pulse is 105 times higher than that of the normal SR.},
doi = {10.1063/1.2436008},
journal = {AIP Conference Proceedings},
number = 1,
volume = 879,
place = {United States},
year = {Fri Jan 19 00:00:00 EST 2007},
month = {Fri Jan 19 00:00:00 EST 2007}
}
  • The infrared-terahertz beamline at UVSOR-II has been upgraded in 2004 for covering very low energy region below 0.3 THz (= 10 cm-). At the beamline, several characteristic experiments in the terahertz region are performed. Two examples of such experiments, reflectivity measurements at low temperatures and at high pressures are reported.
  • We have recently constructed two specialized end stations, one is the terahertz microspectroscopy (THz-MS) and the other the infrared reflection-absorption spectroscopy (SR-IRAS). Both instruments have been tested using synchrotron radiation in the infrared and terahertz regions at UVSOR-II. The THz-MS station covers the wavenumber region of 15,000 -40 cm-1 with the spatial resolution as same as the wavelength. This apparatus is a powerful tool for the electrodynamics on strongly correlated materials at low temperatures and under high pressures and also for the molecular vibration imaging of living cells. On the other hand, the SR-IRAS station covers the IR range downmore » to 300 cm-1 with a high accuracy. The change of Al-N stretching and pyramidalization modes at 423 and 460 cm-1, respectively, due to potassium doping in Alq3 molecules on an Ag surface was observed.« less
  • We are developing coherent light sources at the UVSOR-II electron storage ring. We have developed a resonator type free electron laser in the visible to the deep UV range, coherent harmonic generation source in VUV range and coherent synchrotron radiation source in the terahertz range. A new five year plan has been started from FY2008, where a new 4m straight section will be created by moving the beam injection point, a new optical klystron type undulator will be installed and dedicated beam-lines will be constructed. Great advances on the coherent light source developments at the new straight section are expected.
  • Bursts of coherent synchrotron radiation at far-infrared and millimeter wavelengths have been observed at several storage rings. A microbunching instability has been proposed as the source for the bursts. However,the microbunching mechanism has yet to be elucidated. We provide the first evidence that the bursts are due to a microbunching instability driven by the emission of synchrotron radiation in the bunch. Observations made at the Advanced Light Source are consistent with the values predicted by a model for the microbunching proposed by Heifets and Stupakov. These results demonstrate a new instability regime for high energy synchrotron radiation sources and willmore » impact the design of future sources.« less
  • Electron beam based radiation sources provide electromagnetic radiation for countless applications. The properties of the radiation are primarily determined by the properties of the electron beam. Compact laser driven accelerators are being developed that can provide ultra-short electron bunches (femtosecond duration) with relativistic energies reaching towards a GeV. The electron bunches are produced when an intense laser interacts with a dense plasma and excites a large amplitude plasma density modulation (wakefield) that can trap background electrons and accelerate them to high energies. The short pulse nature of the accelerated bunches and high particle energy offer the possibility of generating radiationmore » from one compact source that ranges from coherent terahertz to gamma rays. The intrinsic synchronization to a laser pulse and unique character of the radiation offers a wide range of possibilities for scientific applications. Two particular radiation source regimes are discussed: Coherent terahertz emission and x-ray emission based on betatron oscillations and Thomson scattering.« less