@article{oai:nifs-repository.repo.nii.ac.jp:00011515,
 author = {TOGASHI, Hiro and EJIRI,  Akira and HASEGAWA, Makoto and HIRATSUKA, Junichi and NAGASHIMA,  Yoshihiko and NAKAMURA, Keishun and NARIHARA,  Kazumichi and TAKASE,  Yuichi and TOJO, Hiroshi and TSUJII, Naoto and YAMADA,  Ichihiro and YAMAGUCHI, Takashi and the TST-2 Team},
 journal = {Plasma and Fusion Research},
 month = {Jan},
 note = {A multi-pass Thomson scattering (TS) system based on confining laser pulses in an optical cavity was constructed for measuring very low-density plasma in the TST-2 spherical tokamak device. This paper describes the setup of the optical system, injection of the laser pulse into the cavity, and properties of the confined laser pulse. A combination of Pockels cell plus polarizer, which serves as an optical shutter, allows us to inject and then confine intense laser pulses in the cavity. A photodiode signal monitoring the very weak light leaking from the cavity mirrors demonstrated that the laser pulse makes many round trips, with a round-trip efficiency of approximately 0.73. The effective number of round trips (i.e., the signal enhancement factor) is approximately 3.7. For an injection efficiency of approximately 0.69, a cavity-confined laser pulse, applied to Thomson scattering, will yield a scattered signal that is five times larger than that from a single-pass laser pulse.},
 title = {Injection and Confinement of a Laser Pulse in an Optical Cavity for Multi-Pass Thomson Scattering Diagnostics in the TST-2 Spherical Tokamak Device},
 volume = {9},
 year = {2014}
}