LINAC2022 - List of Authors (Zen, H.)

Paper

Title

Page

Manipulation and Measurement of Polarization State for THz Coherent Undulator Radiation

69

S. Kashiwagi, H. Hama, F. Hinode, T. Muto, I. Nagasawa, K. Nanbu, H. Saito
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
A. Irizawa
ISIR, Osaka, Japan
H. Zen
Kyoto University, Kyoto, Japan

We are developing an accelerator-based terahertz source that can produce arbitrary polarization states from linearly polarized coherent undulator radiation (CUR). The polarization manipulation of the CUR can be realized using the Martin’Puplett interferometer employed as an optical phase shifter. This study also demonstrates a variable polarization manipulator by using the terahertz CUR (THz-CUR) source based on an extremely short electron bunch at Research Center for Electron Photon Science (ELPH), Tohoku University. The horizontally polarized CUR with a frequency of 1.9 THz was manipulated into variable polarization state, and Stokes parameters were measured to derive the degree of polarization. Beam experimental results will be presented in this conference.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOJO18

About •

Received ※ 09 September 2022 — Revised ※ 18 September 2022 — Accepted ※ 21 September 2022 — Issue date ※ 12 October 2022

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TH2AA01

High Extraction Efficiency Operation of Oscillator-Type Free Electron Laser Driven by a Normal Conducting Linac

H. Zen
Kyoto University, Kyoto, Japan

Funding: MEXT Quantum Leap Flagship Program (MEXT Q-LEAP) Grant Number JPMXS0118070271.
The highest extraction efficiency (9.4%) of a Free Electron Laser (FEL) oscillator has been achieved at the mid-infrared FEL facility of Kyoto University*. The FEL is driven by a normal conducting linac consisting of a thermionic/photocathode RF gun and a traveling wave accelerator tube. The dynamic cavity desynchronization method**,*** was used to achieve the high extraction efficiency with a short macro-pulse duration (7 micro-s). Because of the interaction between the electron beam and FEL electromagnetic field, a maximum electron energy decrease of 16% was observed. An FEL micro-pulse energy of ~100 micro-J with the micro-pulse duration of 150 fs at the wavelength of 11 micro-m was observed. The detailed structure of the FEL micro-pulse was measured using a fringe resolved autocorrelation with a phase retrieval algorithm. As a result, superradiance ringing (or Burnham Chiao ringing), i.e. generation of multiple sub-pulses and 180-degree phase jumps between those sub-pulses, was experimentally observed for the first time in an FEL oscillator.
*H. Zen et al., Applied Physics Express 13, 102007 (2020)
**R.J. Bakker et al., Physical Review E 48, R3256 (1993)
***H. Zen et al., Physical Review Accelerators and Beams 23, 070701 (2020)

please see instructions how to view/control embeded videos

Slides TH2AA01 [0.763 MB]

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper	Title	Page
MOPOJO18	Manipulation and Measurement of Polarization State for THz Coherent Undulator Radiation	69
	S. Kashiwagi, H. Hama, F. Hinode, T. Muto, I. Nagasawa, K. Nanbu, H. Saito Tohoku University, Research Center for Electron Photon Science, Sendai, Japan A. Irizawa ISIR, Osaka, Japan H. Zen Kyoto University, Kyoto, Japan
	We are developing an accelerator-based terahertz source that can produce arbitrary polarization states from linearly polarized coherent undulator radiation (CUR). The polarization manipulation of the CUR can be realized using the Martin’Puplett interferometer employed as an optical phase shifter. This study also demonstrates a variable polarization manipulator by using the terahertz CUR (THz-CUR) source based on an extremely short electron bunch at Research Center for Electron Photon Science (ELPH), Tohoku University. The horizontally polarized CUR with a frequency of 1.9 THz was manipulated into variable polarization state, and Stokes parameters were measured to derive the degree of polarization. Beam experimental results will be presented in this conference.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOJO18
About •	Received ※ 09 September 2022 — Revised ※ 18 September 2022 — Accepted ※ 21 September 2022 — Issue date ※ 12 October 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TH2AA01	High Extraction Efficiency Operation of Oscillator-Type Free Electron Laser Driven by a Normal Conducting Linac
	H. Zen Kyoto University, Kyoto, Japan
	Funding: MEXT Quantum Leap Flagship Program (MEXT Q-LEAP) Grant Number JPMXS0118070271. The highest extraction efficiency (9.4%) of a Free Electron Laser (FEL) oscillator has been achieved at the mid-infrared FEL facility of Kyoto University. The FEL is driven by a normal conducting linac consisting of a thermionic/photocathode RF gun and a traveling wave accelerator tube. The dynamic cavity desynchronization method,** was used to achieve the high extraction efficiency with a short macro-pulse duration (7 micro-s). Because of the interaction between the electron beam and FEL electromagnetic field, a maximum electron energy decrease of 16% was observed. An FEL micro-pulse energy of ~100 micro-J with the micro-pulse duration of 150 fs at the wavelength of 11 micro-m was observed. The detailed structure of the FEL micro-pulse was measured using a fringe resolved autocorrelation with a phase retrieval algorithm. As a result, superradiance ringing (or Burnham Chiao ringing), i.e. generation of multiple sub-pulses and 180-degree phase jumps between those sub-pulses, was experimentally observed for the first time in an FEL oscillator. H. Zen et al., Applied Physics Express 13, 102007 (2020) R.J. Bakker et al., Physical Review E 48, R3256 (1993) **H. Zen et al., Physical Review Accelerators and Beams 23, 070701 (2020)

	please see instructions how to view/control embeded videos
	Slides TH2AA01 [0.763 MB]
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)