JOPSS - Search Results

Journal Articles

Electron density behavior during fast termination phase of post-disruption runaway plasma

Kawano, Yasunori; Nakano, Tomohide; Asakura, Nobuyuki; Tamai, Hiroshi; Isayama, Akihiko; Kondoh, Takashi; Hatae, Takaki; Takenaga, Hidenobu; Ide, Shunsuke

Purazuma, Kaku Yugo Gakkai-Shi, 81(10), p.743 - 744, 2005/10

http://doi.org/10.1585/jspf.81.743

Electron density of post-disruption runaway plasmas in JT-60U has been measured by the tangential CO $_{2}$ laser interferometer. Increases in electron density after the first drop of runaway plasma current have been observed during a fast termination phase of the runaway plasma. At the second current drop, an increase in electron density with multiple spikes or oscillation with the period of 1 ms has been found. It is suggested that the increased electron density seems to take part in the shorter current decay time after the second current drop.

Journal Articles

Recent R&D of Thomson scattering diagnostics for JT-60U and ITER

Hatae, Takaki; Kondoh, Takashi; Naito, Osamu; Nakatsuka, Masahiro*; Yoshida, Hidetsugu*

Proceedings of 12th International Symposium on Laser-Aided Plasma Diagnostics (LAPD-12) (CD-ROM), 6 Pages, 2005/09

no abstracts in English

Journal Articles

Silicon isotope separation utilizing infrared multiphoton dissociation of Si $_{2}$ F $_{6}$ irradiated with two-frequency CO $_{2}$ laser lights

Yokoyama, Atsushi; Oba, Hironori; Hashimoto, Masashi; Katsumata, Keiichi; Akagi, Hiroshi; Ishii, Takeshi*; Oya, Akio*; Arai, Shigeyoshi*

Applied Physics B, 79(7), p.883 - 889, 2004/11

https://doi.org/10.1007/s00340-004-1642-z

Times Cited Count：10 Percentile：42(Optics)

Silicon isotope separation has been done utilizing the Infrared Multiphoton Dissociation of Si $_{2}$ F $_{6}$ irradiated with two-frequency CO $_{2}$ laser lights. The two-frequency excitation method improved the separation efficiency with keeping the high enrichment factors. For example, Si $_{2}$ F $_{6}$ with the $^{28}$ Si fraction of 99.4 % was obtained at 40.0 % dissociation of Si $_{2}$ F $_{6}$ after the simultaneous irradiation of 100 pulses with 966.23 cm $^{-1}$ photons (0.089 J/cm $^{2}$ ) and 954.55 cm $^{-1}$ photons (0.92 J/cm $^{2}$ ), while 1000 pulses were needed to obtain 99.0 % of $^{28}$ Si at 27.2 % dissociation in the case of single frequency irradiation at 954.55 cm $^{-1}$ (0.92 J/cm $^{2}$ ). The single-step enrichment factors of $^{29}$ Si and $^{30}$ Si increased with increasing Si $_{2}$ F $_{6}$ pressure. The reason for this enhancement has been discussed in terms of the rotational and vibrational relaxations by collisions with ambient gases.

Journal Articles

Toroidal interferometer/polarimeter density measurement system on ITER

Kondoh, Takashi; Costley, A. E.*; Sugie, Tatsuo; Kawano, Yasunori; Malaquias, A.*; Walker, C. I.*

Review of Scientific Instruments, 75(10), p.3420 - 3422, 2004/10

https://doi.org/10.1063/1.1786640

Times Cited Count：23 Percentile：72.19(Instruments & Instrumentation)

In order to measure the line average electron density on ITER, a CO $_{2}$ laser interferometer/polarimeter system is being developed. The design of the interferometer/polarimeter is improved from the previous design, which uses CO $_{2}$ and CO laser, on the basis of experience gained with a dual CO $_{2}$ system on JT-60U in which good reliability was confirmed for both interferometry and polarimetry operation. The performance of the dual CO $_{2}$ laser meets requirements for ITER (accuracy; 1%, time resolution; 1 ms).

Journal Articles

High enrichment of $^{28}$ Si by infrared multiple photon decomposition of Si $_{2}$ F $_{6}$

Yokoyama, Atsushi; Oba, Hironori; Shibata, Takemasa; Kawanishi, Shunichi*; Sugimoto, Shunichi*; Ishii, Takeshi*; Oya, Akio*; Miyamoto, Yoshiki*; Isomura, Shohei*; Arai, Shigeyoshi*

Journal of Nuclear Science and Technology, 39(4), p.457 - 462, 2002/04

https://doi.org/10.3327/jnst.39.457

Times Cited Count：3 Percentile：16.96(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Overview of JT-60U diagnostics for reactor-relevant plasma physics

Hatae, Takaki; JT-60 Team

Proceedings of 6th Japan-Australia Workshop on Plasma Diagnostics (CD-ROM), 16 Pages, 2002/00

The diagnostic system of JT-60U is composed of about 50 individual diagnostic devices. Recently, the detailed radial profile measurements of plasma parameters such as electron temperature, electron density, ion temperature, plasma rotation, and plasma current (safety factor q) have been improved. As a result, the understanding of internal structure of plasmas has advanced. In particular, detailed studies of the internal transport barrier could be performed in reversed magnetic shear plasmas. Furthermore, a "current hole" or a nearly zero current density at the plasma center was discovered in JT-60U plasmas by using a motional stark effect (MSE) system. Several diagnostic signal have been linked to actuators such as neutral beam injectors, the gas feed system, and the electron cyclotron heating system establishing the real-time control of electron temperature, neutron yield, radiated power, and electron temperature gradient, and thus improving plasma performance.

Journal Articles