The 77th JSAP Autumn Meeting, 2016

Presentation information

Oral presentation

3 Optics and Photonics » 3.5 Laser system and materials

[13a-B3-1~12] 3.5 Laser system and materials

Tue. Sep 13, 2016 9:00 AM - 12:15 PM B3 (Exhibition Hall)

Shigeki Tokita(Osaka Univ.)

11:45 AM - 12:00 PM

[13a-B3-11] Development of a high average power laser for narrow-bandwidth and high brightness laser Compton scattering X-ray source in cERL

〇(P)Atsushi Kosuge1, Tomoya akagi1, Yosuke Honda1, Sakae Araki1, Junji Urakawa1, Nobuhiro Terunuma1, Michiaki Mori2, Ryoji Nagai2, Toshiyuki Shizuma2, Ryoichi Hajima2 (1.KEK, High Energy Accelerator Research Organization, 2.QST, National Institutes for Quantum and Radiological Science and Technology)

Keywords:laser, enhancement cavity, Energy Recovery linac

There has been a growing interest in the laser-Compton scattering (LCS) light sources because they are capable of producing quasi-monochromatic, bright and tunable X-rays with small source size. By combining a high average power laser and an enhancement cavity with an Energy Recovery linac, high-flux and narrow-bandwidth LCS X-rays can be generated. In this presentation, we will show the LCS X-ray generation results.
For the LCS X-ray generation experiment, we employ a commercial passively mode-locked diode pumped solid state laser system with maximum average power of 45 W, wavelength of 1064 nm, repetition rate of 162.5 MHz, and pulse duration of 10 ps. The ejected laser beam is passed through a mode matching telescope and injected to a four-mirror enhancement cavity with two concave mirrors to produce a small spot laser beam inside a cavity. The circling intracavity power is determined by measuring the power leaking from a cavity mirror. From this measurement, when the injection power was 24 W, a circulating power of 10 kW was obtained.
The cERL is a superconducting test accelerator to demonstrate both low-emittance and high average current operation in an energy recovery linac. The electron beam with bunch charge of 5.5 pC and bunch length of 2 ps was accelerated to 20 MeV and was transported to the collision point. The laser pulses and electron beam must be synchronized to achieve collision. This synchronization is realized with a Pound–Drever–Hall method and a phase locked loop method.
In the LCS X-ray generation experiment, around 7 keV X-ray was generated by collision of 1064 nm laser photons and 20 MeV electrons at an angle of 18 deg. A silicon drift detector (SDD) used for the LCS X-ray observation was placed 16.6 m from collision point. In this presentation, I am going to report in detail on some of the highlight result taken from the LCS X-ray generation experiment.