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An incoherent Thomson scattering diagnostic will be installed in the JT-60SA tokamak to measure electron temperature and electron density profiles. The target radial spatial resolution is 25 mm with 46 spatial channels. The accuracy in electron temperature and density is a few percent at ne = 7.5 × 1019 m−3, which is the expected value in the plasma core. This paper presents the designs of collection optics, fibers with their alignment system, and polychromators. The collection optics overcomes unique issues for superconducting fusion devices, i.e., limited design space, high-temperature measurements, and harsh radiation condition. When in several years the more performing plasma will generate intense nuclear radiation, the lens materials of the optics can be replaced by radiation resistant glasses without major changes in the lens holder. It will prevent transmission degradation and keep stable measurement accuracy. [ABSTRACT FROM AUTHOR]

Energy confinement properties for hydrogen and deuterium H-mode plasmas are investigated. The thermal energy confinement time becomes longer in deuterium by a factor of ~1.4 than in hydrogen at a given absorbed power. When the absorbed power is fixed, the values of electron temperature Te and ion temperature Ti become explicitly higher in deuterium than in hydrogen across the whole range of minor radius while the profiles of electron density ne are almost the same. Accordingly, the effective heat diffusivity becomes relatively lower in deuterium than in hydrogen. Despite almost the same power crossing the separatrix, type-I ELM frequency for hydrogen becomes approximately double that of deuterium. When the stored energy is fixed, the spatial profiles of ne, Te and Ti become identical for both cases while higher heating power is required in the hydrogen case. The pedestal pressure is about twice as high in deuterium as that in hydrogen at a given absorbed power. The increase of the pedestal temperature is more significant for the deuterium case while the pedestal density is not changed. The poloidal beta at the H-mode pedestal βpped is increased linearly with the increased total poloidal beta βpTOT for both cases. The relation between βpTOT and βpped is almost identical regardless of the difference of the isotope species. [ABSTRACT FROM AUTHOR]

The multichannel motional Stark effect (MSE) diagnostic system in JT-60U has been upgraded to measure density fluctuation profile. A 16-channel fast-sampling digitizer has been added in order to measure photomultiplier-tube signals at measurement frequency of 0.5–1 MHz. The new system works as a MSE and beam emission spectroscopy diagnostic. Spatially resolved electron density fluctuation profile measurement in various operation regimes is presented. In the core plasma, density fluctuation induced by rotation of tearing mode islands was observed. Temporal evolution of the fluctuation frequency agrees with that measured by Mirnov coils (poloidal and toroidal mode numbers: 2 and 1, respectively). The phases of the fluctuations on either side of the q=2 surface are inverted, which is consistent with electron cyclotron emission. These measurements show that the density fluctuation is caused by a rotating magnetic island structure induced by the tearing mode. In the scrape-off layer of a H-mode plasma with edge-localized-mode (ELM), i. e., ELMy H-mode outward propagation of strong intermittent emission corresponding to ELM crash was also observed. The propagation velocity is 0.69–2.2 km/s along the MSE measurement points, the time lag and distance between adjacent channels being 67±35 μs and 70 mm, respectively. [ABSTRACT FROM AUTHOR]

An analytical model of fluctuation reflectometry is developed, which is capable of handling the plasma profiles of arbitrary shape and curvature. The experimental profiles are piece-wise approximated by the functions, which allow for the integration of the full-wave O-mode equation. The model is applied to the reflectometry of the JT-60U tokamak plasma to provide a preliminary estimation of the fluctuation amplitude and spectral width. [ABSTRACT FROM AUTHOR]

Describes the development of the ultrashort-pulse reflectometry system for electron density profile and fluctuation measurements on the GAMMA 10 tandem mirror. Device description and experimental setup; Measurement of the double-pass time-of-flight from the vacuum window to the cutoff layer; Uncertainty value and repetition rate of the system.

Proposes a method of measuring plasma density in the microwave reflectometer signal. Use of wavelet analysis in the method; Achievement of a radial electron density profile; Inclusion of calibration and solution of for integral equation in the electron density reconstruction algorithm.