Common-path achromatic rotational-shearing coronagraph

To suppress starlight for direct exoplanet observation, we propose a common-path achromatic rotational-shearing coronagraph (CP-ARC), which is an interferocoronagraph with an angular-adjustable field rotator. The CP-ARC aims to maintain unwanted detection of stellar light, which can be suppressed incompletely by interference because of the finite diameter of the star. Compared to the previous interferocoronagraph, which had a nonadjustable 180° field rotation, the proposed CP-ARC can improve the coronagraphic contrast by several orders if the CP-ARC is combined with medium or large telescopes where the companion-star separation is optically resolved by more than a few Airy radii. The CP-ARC is made robust against mechanical disturbances due to the common-path interferometer principle.     

Laser-induced fluorescence of seeded nitric oxide as a flame thermometer

Received: 10 June 1997/Revised version: 25 November 1997     

Reduction of ion thermal diffusivity associated with the transition of the radial electric field in neutral-beam-heated plasmas in the large helical device

Recent large helical device experiments revealed that the transition from ion root to electron root occurred for the first time in neutral-beam-heated discharges, where no nonthermal electrons exist. The measured values of the radial electric field were found to be in qualitative agreement with those estimated by neoclassical theory. A clear reduction of ion thermal diffusivity was observed after the mode transition from ion root to electron root as predicted by neoclassical theory when the neoclassical ion loss is more dominant than the anomalous ion loss.     

Mass spectrometric studies on gibberellins

Based on the element maps of twenty-two gibberellin methyl esters fragmentations are discussed, which are characteristic of the common structural features as well as structural modification in gibberellin homologues.     

Regularized determinants for quantum field theories with fermions

A new type of regularized determinant for the ratio of two Dirac operators is presented. Some of its properties with application to the chiral anomaly are given.     

Surface magnetism of Fe(110) from polarized electron scattering

Exchange- and spin—orbit-induced scattering asymmetry spectra of polarized slow electrons from the ferromagnetic Fe(110) surface have been calculated by dynamical theory and found to agree with recent experimental data taken at room temperature. Comparison of exchange asymmetry spectra, obtained for various interaction and layer-dependent magnetization models, with the data implies firstly an enhancement of the surface magnetization by about 30% with respect to the bulk, and secondly the importance of spin-dependent localized inelastic electron—electron scattering processes.     

Measuring grain rotation at the nanoscale

In this paper, we introduced a method to measure grain rotation of nanomaterials under external stress using a high pressure diamond anvil cell and the Laue microdiffraction technique at a synchrotron facility. We used tungsten carbide marker crystals to investigate grain rotation activities of 3 and 500?nm nickel media. Our results show that the grain rotation of 3 and 500?nm nickel nanocrystals increase with pressure and finally rotation of 500?nm nickel tends to stop at a lower pressure/stress level than 3?nm nickel. 3?nm nickel nanocrystals show a higher rotation magnitude than 500?nm nickel nanocrystals. Our measurements show an effective method to study the grain rotation of nanomaterials especially in ultrafine nanocrystals.     

Simultaneous Laser-Induced Fluorescence Imaging of Unburnt and Reacting Areas in Combustion Fields Using a KrF Excimer Laser

Simultaneous two-dimensional imaging of an unburnt area and a reacting area was performed using laser-induced fluorescence. Acetone was added to fuel as a tracer, and OH radical was used as a marker of the reacting area. A narrow band tunable KrF excimer laser (248 nm) was employed to excite acetone and OH simultaneously. Two intensified CCD cameras with different wavelength filters were used to detect these two kinds of species respectively. Detecting 294-314 nm (A-X (3, 2), etc.) for OH and 335-410 nm for acetone, we obtained images of each species without interference of a signal from the other. The method was also successfully applied to flames in a pressurized combustion chamber under the pressure of 0.5 MPa.