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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

Prospects for $$alpha$$-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.

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

 Times Cited Count:19 Percentile:68.06(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, 1$$mu$$m, 0.6 $$mu$$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

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 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 10.6$$mu$$m, beam energy 15 J, pulse width 1$$mu$$s) 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

Ion temperature measurements on JT-60U by collective thomson scattering using a CO$$_{2}$$ laser system

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

Purazuma, Kaku Yugo Gakkai-Shi, 76(9), p.883 - 887, 2000/09

no abstracts in English

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