Toroidal momentum transport is examined experimentally by using on-and off-axis tangential neutral beam injections on the JT-60U tokamak. From a steady state momentum balance analysison the assumption that momentum flux is diffusiveit is found that the profiles of the momentum diffusivity are quite different in the two cases of on-and off-axis beam injections. In addition, transient toroidal momentum transport was examined by using a momentum source modulation experiment. On the assumption that the toroidal momentum flux consists of a diffusive and a convective flow term, it is found that there is non-diffusive inward flux of toroidal momentum whose absolute value is comparable to that of the diffusive flux.

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As a result of an experiment at JT-60U on H mode transition power threshold scaling, which is one of the urgent ITER Physics R&D issues, it has been found that: (a) the derived scaling law of Pth(MW)=0.18ne0.5 (1019 m-3) BT1.0 (T) R1.5 (m) with presumed non-dimensional constraints predicts a threshold heating power of ⩽ 100 MW at 5 × 1019 m-3 for the ITER EDA design, and (b) an increase of the neutral particle density at the plasma edge results in a reduction of the edge ion collisionality just before the transition below unity and thereby an increase of the threshold heating power. It has also been found that both the low density boundary, below which the transition cannot occur, and the apparent density dependence of the threshold power scaling are related to the edge neutrals. It is suggested that a charge exchange process might well be the potential mechanism of the neutral effect

The particle diffusivity and the convection velocity in the reversed shear plasma of JT-60U were separately evaluated based on the perturbation technique using modulated helium gas-puffing. The particle diffusivity in the region of internal transport barrier was reduced by about a factor of two compared with that in the inside region. The inward convection velocity was observed in the region of internal transport barrier, while the outward convection velocity was observed in the inside region. These results indicate that the changes in both the particle diffusivity and the convection velocity are related to the formation of the internal transport barrier.

A previous experiment in JT-60U supported an orbit following Monte Carlo (OFMC) calculation regarding ripple trapped loss, and the present experiment, furthermore, suggests that the OFMC also predicts banana drift loss fairly well. In the experiment presented, the total fast ion losses due to toroidal field ripple were estimated from the decay in neutron emission following a short neutral beam injection (90 keV, D). The neutron decay for co-passing beam injection showed a diffusivity of about 0 m2/s, which indicates no fast ion loss. In contrast, the neutron decay for trapped particle injection exhibited characteristic enhancement of fast ion losses due to toroidal field ripple: the fast ion losses consisted of ripple trapped convection and ripple banana diffusion in the low collisionality regime. The OFMC calculation reconstructed completely the experimental neutron decay irrespective of the total ripple losses and the fraction of banana drift loss. Considering the previous work on ripple trapped loss and this result, it can be concluded that the OFMC code gives a good quantitative estimation of banana drift loss as well as ripple trapped loss

The scintillation properties of a hydrothermal method grown zinc oxide (ZnO) crystal are evaluated for extreme ultraviolet (EUV) laser excitation at 13.9nm wavelength. The exciton emission lifetime at around 380nm is determined to be 1.1ns, almost identical to ultraviolet laser excitation cases. This fast response time is sufficiently short for characterizing EUV lithography light sources having a few nanoseconds duration. The availability of large size ZnO crystal up to 3in. is quite attractive for future lithography and imaging applications.

We have developed a new method to investigate the relaxation time of the dipole moment in polarization clusters in BaTiO3. Time correlation of speckle intensities was measured by the use of a double pulsed soft x-ray laser. The evolution of the relaxation time of the dipole moment near the Curie temperature (T(C)) was investigated. The maximum relaxation time (approximately 90 ps) is shown to appear at a temperature of 4.5 K above the T(C), being coincident with the one where the maximum polarization takes place. This method is widely applicable to any other critical decay processes at phase transitions.

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