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Journal Articles

Applications of stimulated brillouin scattering phase conjugate mirror to Thomson scattering diagnostics in JT-60U and ITER

Hatae, Takaki; Naito, Osamu; Kitamura, Shigeru; Sakuma, Takeshi*; Hamano, Takashi*; Nakatsuka, Masahiro*; Yoshida, Hidetsugu*

Journal of the Korean Physical Society, 49, p.S160 - S164, 2006/12

no abstracts in English

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

Improvement of Thomson scattering diagnostics using stimulated-Brillouin-scattering-based phase conjugate mirrors

Hatae, Takaki; Nakatsuka, Masahiro*; Yoshida, Hidetsugu*

Purazuma, Kaku Yugo Gakkai-Shi, 80(10), p.870 - 882, 2004/10

http://ci.nii.ac.jp/naid/110003827868

A high performance phase conjugate mirror by stimulated Brillouin scattering (SBS-PCM) is applied to Thomson scattering diagnostics in JT-60U for the first time. To improve the measurement performance, two developments were performed with SBS-PCM. First, we developed a new optical design to provide a double-pass scattering scheme with SBS-PCM. A laser beam passing through the plasma is reflected by the SBS-PCM, and a reflected beam returned back through the same path as coming one by the phase conjugate effect, and passed through the plasma again. The double path Thomson scattering scheme demonstrated in JT-60U plasma that a factor of 1.6 increase of the scattered light in contrast with single-pass scattering. Second, an improvement of the output power of YAG laser system using the SBS-PCM was performed. As a result, average power was increased over 8 times in contrast with conventional system, and was achieved up to 368 W (7.4 J 50 Hz). A multi-pass Thomson scattering scheme is also proposed based on the results of double-pass scattering.

Journal Articles

Laser pattern profile emitted through optical glass fiber bundle with load

Yamauchi, Toshihiko

Japanese Journal of Applied Physics, 43(9A), p.6473 - 6474, 2004/09

https://doi.org/10.1143/JJAP.43.6473

Times Cited Count：0 Percentile：0(Physics, Applied)

The output pattern of He-Ne laser that passes through the optical glass fiber bundle used for free electron laser etc. depends on the weight of load (modulation of transverse mode). The increment of pattern radius exponentially increases with the load. It is considered that the micro bending causes this increment. Next, the estimated delay time also exponentially increases with the weight of load, and the estimated delay time is the extent of pico-second.

Journal Articles

Interference between thomson scattering and resonant scattering in X-ray diffraction from CeB $_{6}$

Nagao, Tatsuya*; Igarashi, Junichi

Journal of the Physical Society of Japan, 72(9), p.2381 - 2384, 2003/09

https://doi.org/10.1143/JPSJ.72.2381

Times Cited Count：10 Percentile：55.03(Physics, Multidisciplinary)

We examine the mechanism of the X-ray diffraction process by including the Thomson scattering (TS) term in addition to the resonant X-ray scattering (RXS) term near the Ce L absorption edge in the antiferroquadrupole (AFQ) ordering phase of CeB $_{6}$ . Assuming the AFQ order in the 4f states but without any lattice distortion, we obtain the TS intensity comparable to the RXS intensity, owing to the anisotropic charge distribution of 4f states. The present calculation reproduces well the interference pattern between the TS and RXS terms for the (5/2,3/2,3/2) spot observed in the recent experiment. The result suggests that the TS signal as well as the main peak of the RXS signal are a direct reflection of the AFQ order in CeB $_{6}$ .

Journal Articles

Prospects for -particle diagnostics by CO $_{2}$ laser collective Thomson scattering in ITER

Kondoh, Takashi; Richards, R. K.*; Hutchinson, D. P.*; Sugie, Tatsuo; Costley, A. E.*; Miura, Yukitoshi; Lee, S.*

Proceedings of 30th EPS Conference on Controlled Fusion and Plasma Physics (CD-ROM), 4 Pages, 2003/07

In order to understand the behavior of alpha-particles which are the dominant heat source in a burning plasma, it is necessary to measure the spatial distribution of the number of the alpha-particles and their energy spectrum. A collective Thomson scattering (CTS) system based on a pulsed CO $_{2}$ laser is being developed and is under consideration for alpha-particle measurements on ITER. Heating beam ions (E = 1 MeV) are normally co-injected and have a similar velocity with alpha-particles in ITER. The CTS measurement can not, in general, distinguish beam ions and alpha-particles which have the same velocity. A vertical scattering geometry to distinguish between beam ions and alpha-particles is proposed. Calculations have shown that the vertically viewing CTS can resolve counter-travelling alphas without being masked by beam ions. Preliminary design of a beam line and a receiver system with the vertical scattering geometry has been developed. A proof-of-principle test on the CTS system using the JT-60U plasma is being conducted.

JAEA Reports

Inferring $Z_{eff}$ spatial profile from background light in incoherent Thomson scattering diagnostic

Naito, Osamu; Hatae, Takaki

JAERI-Research 2002-033, 9 Pages, 2003/03

JAERI-Research-2002-033.pdf:0.46MB

A simulation study on the feasibility of inferring spatial $Z_{eff}$ profile along with electron temperature and density in Thomson scattering diagnostic is presented. The background signal, which is usually discarded after subtracted from the Thomson scattered signal, is used in the reconstruction procedure. If the contribution from line radiation to the background signal is by one order of magnitude smaller than that from bremsstrahlung, a fairly accurate $Z_{eff}$ profile can be reconstructed.

Journal Articles

Collective Thomson scattering based on CO $_{2}$ laser for ion energy spectrum measurements in JT-60U

Kondoh, Takashi; Miura, Yukitoshi; Lee, S.*; Richards, R. K.*; Hutchinson, D. P.*; Bennett, C. A.*

Review of Scientific Instruments, 74(3), p.1642 - 1645, 2003/03

https://doi.org/10.1063/1.1532760

Times Cited Count：20 Percentile：68.22(Instruments & Instrumentation)

Measurements of energy spectrum and density profile of confined alpha-particles are required for ITER. Several methods have been proposed, however, a measurement technique hasn't been established yet. A collective Thomson scattering (CTS) system based on a pulsed CO $_{2}$ laser is being developed to demonstrate feasibility of alpha-particle diagnostics for ITER. The pulse laser (15J, 1m, 0.6 m) and a wide band (~ 8GHz) heterodyne receiver with a quantum-well infrared photodetector (QWIP) have been developed and installed in the JT-60U tokamak. Stray light is reduced by a notch filter with hot CO $_{2}$ gas. Heterodyne receiver is absolutely calibrated using large area blackbody radiation source. Scattered signal from JT-60U plasma has not detected because of electrical noise originated from discharge of the pulsed laser and stray signal caused by impurity of the spectrum of the pulsed laser.

Journal Articles

Utilization of background signal for inference of $Z_{eff}$ spatial profile in incoherent Thomson scattering diagnostic

Naito, Osamu; Hatae, Takaki

Review of Scientific Instruments, 74(3), p.1374 - 1376, 2003/03

https://doi.org/10.1063/1.1535738

Times Cited Count：0 Percentile：0.01(Instruments & Instrumentation)

A simulation study on the feasibility of inferring spatial $Z_{eff}$ profile along with electron temperature and density in Thomson scattering diagnostic is presented. The background signal, which is usually discarded after subtracted from the Thomson scattered signal, is used in the reconstruction procedure. If the background signal consists predominantly of bremsstrahlung radiation, a fairly accurate $Z_{eff}$ profile can be reconstructed. Additional benefit of including background signal in the reconstruction is the reduction of errors in the inferred electron temperature and density.

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

Collective Thomson scattering using a pulsed CO $_{2}$ laser in JT-60U

Kondoh, Takashi; Lee, S.; Hutchinson, D. P.*; Richards, R. K.*

Review of Scientific Instruments, 72(1), p.1143 - 1146, 2001/01

https://doi.org/10.1063/1.1322616

Times Cited Count：13 Percentile：59.42(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Collective Thomson scattering based on a pulsed CO $_{2}$ laser in JT-60U

Kondoh, Takashi; Lee, S.; Miura, Yukitoshi

Proceedings of 10th International Symposium on Laser-Aided Plasma Diagnostics, p.109 - 114, 2001/00

A collective Thomson scattering (CTS) diagnostic system based on a CO $_{2}$ laser has come into operation to establish measurement technique of ion temperature and fast alpha particle in fusion plasmas. A pulsed CO2 laser (wavelength 10.6m, beam energy 15 J, pulse width 1s) and a heterodyne receiver were developed by Oak Ridge National Laboratory (ORNL) and were installed in the JT-60U tokamak. Commissioning of the CTS system by injecting the CO $_{2}$ laser into the plasmas has been proceeded.

Journal Articles

Very high electron temperature diagnostics using combined ruby and YAG laser Thomson scattering systems in JT-60U

Hatae, Takaki; Naito, Osamu

Proceedings of 10th International Symposium on Laser-Aided Plasma Diagnostics, p.160 - 166, 2001/00

In recent strong electron heating experiments in JT-60U, it seems that central ${it T$_{e}$}$ rises above 15 keV which is measured by Ruby laser and YAG laser Thomson scattering systems. However, error bars are relatively large and it is difficult to measure the very high ${it T$_{e}$}$ beyond 15 keV with high accuracy because the electron temperature region exceeds that of the original design. To improve the measurement performance in very high ${it T$_{e}$}$ , we have tried the combination of existing Ruby laser system and YAG laser system. From simulations, it was found that (1) changing the form of the spectrum with the other laser is an effective way for very high ${it T$_{e}$}$ measurement, (2) furthermore the combined system in YAG laser scattering is well optimized at ${it T$_{e}$}$ 20keV and relative error is reduced significantly compared with original system.