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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 3780-3781 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The necessary number of wavelength channels is investigated in incoherent Thomson scattering diagnostics. The measurement errors (σ) are evaluated for a realistic case and their lower limits (σ˜) are given in explicit forms. For a given number of wavelength channels, optimal channel allocation in the wavelength space is sought by minimizing the average relative errors. As a scale of the goodness of measurement, we introduce the ratio 〈σ˜/σ〉 averaged over the electron temperature of interest. This quantity ranges from 0 to 1 and tends to 1 as the lowest achievable error is approached. If we conclude that 〈σ˜/σ〉≥0.9 is sufficient, then for a typical ruby laser system measuring 400–700 nm, seven channels is an adequate number for covering the electron temperature of 0.01–10 keV and five channels for 0.1–10 keV. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 1152-1161 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The design concept and operation performance of a novel alignment system for accurate electron density profile measurement is presented, which has been developed on the basis of the original method for adjusting quantitatively and actively an object field of collection fiber optics to a laser-beam axis. The quantitative expression needed for an appropriate alignment was able to be formulated using the beam width measured in situ by this alignment system and the four laser scattering intensity signals from special alignment fiber bundles. The effectiveness of this alignment system for precise and reliable measurement of electron density has been successfully demonstrated in the JT-60U Thomson scattering diagnostic through direct monitoring and quick restoration of alignment. The important and distinctive feature of this alignment system is to attain compatibility between a stable and accurate maintenance of alignment and an improvement of the signal-to-noise ratio of Thomson scattering to plasma light accompanying the reduced fiber bundle width. © 1997 American Institute of Physics.
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  • 3
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A compact and two dimensional detector has been developed for the JT-60U Thomson scattering system, that consists mainly of a proximity focused image intensifier, a 20×12 spatially and spectrally arrayed silicon photodiode, and a data processing unit enabling high repetitive measurement at 1 kHz. To secure a wide spectral bandwidth for an effective detection of the Thomson scattering spectrum, we have introduced a spectrometer and lens systems with enhanced transmission in a longer wavelength, which can compensate for the decreasing characteristic of quantum efficiency of a transmission-mode photocathode used in the image intensifier. The spectral divide of the photodiode array is designed to give its full performance in a wide electron temperature (Te) range of 0.2–15 keV with 12 spectral channels. The application of this newly developed detector to the JT-60U core plasma measurement is also presented. © 1999 American Institute of Physics.
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  • 4
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The design and operation performance of the latest ruby Thomson scattering system for the JT-60U are described, which includes many novel approaches to attain the repetitive measurement of 60 spatial points with high resolution (8 mm), precision, and reliability especially for a high temperature and large size tokamak device. A beam combiner composed of a polarizer and a Faraday rotator for two ruby lasers has provided the transient measurement with the minimum time interval of 2 ms in burst operation and the multitime-slice measurement with the repetition rate of 0.5 Hz in normal operation. A newly developed photodiode array detector with high repetitive ability of 1 ms has been used for the high temperature core plasma measurement. A quantitative alignment of collection fiber object field has been utilized for the reliable ne profile measurement. By using Rayleigh scattering light, an in situ inferring method for a coated viewing window transmission has been found to have an effect on the precise correction of electron temperature Te and density ne underestimate for high Te plasmas. Making the most use of this diagnostic in a series of the recent JT-60U reversed shear experiments, the formation of an internal transport barrier even for electrons has been revealed from the clear existence of a steep gradient in both Te and ne profile shapes. © 1999 American Institute of Physics.
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  • 5
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A YAG laser Thomson scattering system has been developed to measure the time evolution of electron temperature (Te) and density (ne) profiles in the JT-60U. Presently this system provides Te and ne periodically every 100 ms (20 ms at the minimum) at 15 spatial channels. A six spectrum channel polychromator, which is a successive interference filter type, was designed to measure a wide Te range (20 eV–20 keV) by using five channels. The sixth channel is used for calibration by Rayleigh scattering. However, we also used the Rayleigh channel to measure Te and ne since the stray light level was very low. As a result, we were able to measure temperatures below 20 eV. The temperature of the silicon avalanche photodiode (APD) is stabilized by a Péltier element so that the gain is kept constant within ±0.5%. The stable performance of the APD enables accurate Te and ne measurement. During plasma operation, the electron temperature is measured over a wide range from the low temperature plasmas in the runaway plasma current tail generated by a killer pellet to the high temperatures of high performance negative shear plasmas. © 1999 American Institute of Physics.
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 143-147 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A beam combine method of two ruby lasers has been developed for the JT-60 Thomson scattering system, that is mainly composed of a polarizer plate and a Faraday rotator. By this method we have achieved a minimum time interval of 2 ms between the two laser pulses homogeneously combined. Also a high energy transmission of more than 95% has been attained. As a result, transient phenomena measurement can be available especially for pellet-injected plasmas by using the Thomson scattering system. The beam combine method applied to JT-60 is very attractive in terms of upgrading a Thomson scattering system to a high repetition diagnostic without any essential change of the existing equipment, and has been working with no serious trouble since 1989. The application of this method to a multilaser system with three or more lasers is also discussed for the practical purpose of improving a repetition rate of high power pulsed laser. © 1995 American Institute of Physics.
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 56 (2000), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Hatchery-reared honmasu salmon Oncorhynchus rhodurus × masou parr released into the Yanagisawa River, Tochigi Prefecture on 24 June 1996 increased significantly in length and weight by November, while siblings retained in hatchery tanks did not. Plasma growth hormone (GH) levels of the released parr increased from 1 day after the release until 23 August, while the GH levels of the wild parr in the river did not increase. The released parr started to consume various natural prey organisms within a day after release. However, stomach fullness of the released parr was considerably lower than that of the wild parr during the first week following release. Trypsin activity in the released parr increased after 23 August, 2 months post-release. The results demonstrate that the released parr adapt to the natural river environment within weeks. Endocrine control by GH and exocrine pancreas activity appear to play important roles in the post-release adaptation processes.
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