15-19 April 2018
Paradise Point Resort & Spa
America/Los_Angeles timezone

12.53 Nd:YAG laser Thomson scattering diagnostics for laboratory magnetosphere

18 Apr 2018, 20:30
2h 1m
Paradise Point Resort & Spa

Paradise Point Resort & Spa

1404 Vacation Rd, San Diego, CA 92109

Speakers

Naoki Kenmochi (Graduate School of Frontier Sciences, The University of Tokyo) Masaki Nishiura (Graduate School of Frontier Sciences, The University of Tokyo) Zensho Yoshida (Graduate School of Frontier Sciences, The University of Tokyo) Ichihiro Yamada (National Institute for Fusion Science) Hisamichi Funaba (National Institute for Fusion Science) Tetsuya Sugata (Graduate School of Frontier Sciences, The University of Tokyo) Kaori Nakamura (Graduate School of Frontier Sciences, The University of Tokyo) Shotaro Katsura (Graduate School of Frontier Sciences, The University of Tokyo)

Description

Stable confinement of high-beta (local electron beta ~ 1) is demonstrated with high-energy electrons (T_e > 10 keV) by an X-ray measurement in the RT-1 magnetospheric plasmas. A new Nd:YAG laser Thomson scattering (TS) system has been developed to investigate the mechanism of the high-beta plasma formation in the RT-1. The designed parameters for the TS system is 10 eV < T_e < 50 keV and n_e > 1.0 x 10^{17} m^{-3}. In order to obtain the sufficient amount of scattered light for the low-density plasmas, we adopted the long scattered length (60 mm) and a bright optical system with both large collection window (Φ=260 mm) and large collection lens (Φ=300 mm). The system employs a Nd:YAG laser of 1.2 J (oscillation frequency: 10 Hz) with a scattering length of 60 mm (scattering angle: 90 degrees). Scattered light is collected by one set of lens (f/2.0, NA = 0.145) with a solid angle of ~ 68 m str and guided to an interference filter polychromator through an optical fiber bundle. As a test measurement and calibration, the Raman scattering signals were successfully obtained in N_2 gas. We found that the collection optics realizes a sufficient signal-to-noise ratio above n_e ~ 10^{17} m^{-3}. We also observed that the spectrum of TS light changes with the RT-1 plasma parameters.

Primary author

Naoki Kenmochi (Graduate School of Frontier Sciences, The University of Tokyo)

Co-authors

Masaki Nishiura (Graduate School of Frontier Sciences, The University of Tokyo) Zensho Yoshida (Graduate School of Frontier Sciences, The University of Tokyo) Ichihiro Yamada (National Institute for Fusion Science) Hisamichi Funaba (National Institute for Fusion Science) Tetsuya Sugata (Graduate School of Frontier Sciences, The University of Tokyo) Kaori Nakamura (Graduate School of Frontier Sciences, The University of Tokyo) Shotaro Katsura (Graduate School of Frontier Sciences, The University of Tokyo)

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