[en] Depth profiles of the Ag grains density in autoradiographs, which represent tritium concentration in CX-2002U samples exposed to high flux D/T particles under various conditions, were examined and the apparent diffusion coefficients were estimated from the profiles. Plasma discharge generating D/T atomized particles with low energies increases tritium inventory in the samples by introducing high tritium concentration on the surface exposed and following diffusion process into the deep region with apparent diffusion coefficients (1.7x10^-16 m²/s at 293 K and 2.3x10^-15 m²/s at 573 K), which are much larger than the diffusion coefficients in the bulk reported. Oxygen RF-plasma exposure might be effective to remove tritium retained even at a fairly deep region in carbon fiber composite (CFC) components

[en] In order to search for techniques to mitigate disruptions, the characteristics of disruptive I_p decays were tested for (1) low and high vacuum vessel loop resistance Ω_v conditions, and (2) scrape-off layer (SOL) plasma to vessel current (halo current) control. These tests were to manipulate the SOL current. Case (1) had the advantage of lower loop voltage V₁ without an increase of the force due to the eddy current, in comparison with high Ω_v conditions. In case (2), the I_p decay rate was reduced by suppressing the SOL current. The core plasma current and the shell effect during the first phase, in which magnetic axis and core plasma still exist with the closed flux surfaces, were enhanced, which is effective in mitigating disruptive I_p decay. (author). 12 refs, 7 figs

[en] The triple differential cross sections for the ⁶Li(e,e'p) reaction have been measured in the excitation energy range from 27 to 46 MeV in a search for evidence of the giant dipole resonance (GDR) in ⁶Li. The cross sections have no distinct structures in this energy region, and decrease smoothly with the energy transfer. Angular distributions are different from those expected with the GDR. Protons are emitted strongly in the momentum-transfer direction. The data are well reproduced by a DWIA calculation assuming a direct proton knockout process

[en] To develop a new method for decontamination of tritium retained in the carbon fiber composites (CFC) tiles and other components of D-T fusion reactors, a preliminary experiment using ultra violet (UV) light source was performed. Samples simulating a co-deposited layer were prepared by glow discharge using C₂H₂ and a tungsten or CFC substrate. The UV light from a xenon excimer lump (172 nm) was irradiated to the samples in 423 K. Small amounts of species were released only by the heating procedure to 423 K. By UV irradiation, large quantities of hydrogen, carbon and hydrocarbons were released from the samples. Fourier Transform Infrared (FT-IR) analysis showed hydrocarbons were formed on the sample by acetylene glow discharge and C-H bonds were decomposed by irradiation with UV light. It is concluded that the combination of heating and UV irradiation causes release of tritium from the surface of the materials

[en] Tritium retention in CX-2002U was studied by exposure to high flux of D/T atomized particles. The amount of tritium retained in CX-2002U appeared to be proportional to the half power of total incident fluence below 597 K and to the one third power at 897 K. No saturation was observed up to 10²⁷ atoms/m² at 297 K. The tritium concentration profile was also measured by means of autoradiography, from which an overall diffusion coefficient of D_t = 3.6 x 10¹⁴ m²/s at room temperature was estimated. This value, which was much larger than the reported bulk diffusion coefficient, implies additional diffusion processes such as pore diffusion of tritium atoms or molecules. Tritium removal from the sample by exposure to air and helium plasma after irradiation of D/T atomized particles was studied. Tritium retention was reduced by about one tenth during air plasma exposure and by about a half during helium plasma exposure. (orig.)

[en] Reactive ion beam etching (RIBE) is an effective dry etching technique for the fabrication of micro-sized surface emitting (SE) lasers and optoelectronic devices. In this chapter, some etching characteristics for GaAs, InP and GaInAsP with a Cl₂ gas using an RIBE system are discussed. Micro-sized circular mesas including GaInAsP/InP multilayers with vertical sidewalls were fabricated. RIBE-induced damage in InP substrates was estimated by C-V and PL measurement. In addition, the removal of the induced damage by the second RIBE with different conditions for the InP wafer was proposed. The sidewall damage is characterized by photoluminescence emitted from the etched sidewall of a GaInAsP/InP DH wafer. (orig.)

[en] We have developed a spectroscopic transmission-type four detector polarimeter (T-FDP). It consists of a detector head and a multichannel spectrometer equipped with a two-dimensional CCD detector. Inside the T-FDP, three cubic beam splitters are aligned in a straight line and they are rotated relative to each other. From the responses of the spectroscopic T-FDP to five inputs with known polarization states it is possible to determine the characteristic matrices of the T-FDP at various wavelengths. The trajectories of the experimentally measured polarization states on the Poincare sphere agree well with theoretical predictions. These results demonstrate the feasibility of using the T-FDP for spectroscopic ellipsometry.

[en] The energy spectra and angular distributions of protons from the ¹²C(e,e^primep) coincidence reaction have been measured at azimuthal angles of φ_p=-45 ^circle and -135 ^circle out of the scattering plane, at energy transfer of 40 MeV and momentum transfer of 0.35 fm^-1 (69 MeV/c). The longitudinal-transverse interference term, as well as the non-interference term of the (e,e^primep₀) cross section have been obtained, and the transition amplitudes are deduced in the LS coupling basis. The cross sections are compared with an RPA calculation. The photo-reaction cross section derived from the transverse term is in reasonable agreement with previous experimental results. ((orig.))