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Relativistic electron beam transport through a high-density, magnetized plasma is studied numerically and theoretically. An electron beam injected into a cold plasma excites Weibel and two-stream instabilities that heat the beam and saturate. In the absence of an applied magnetic field, the heated beam continues to propagate. However, when a magnetic field of particular strength is applied along the direction of beam propagation, a secondary instability of off-angle whistler modes is excited. These modes then couple nonlinearly creating a large amplitude parallel-propagating whistler that stops the beam. Here, we will show these phenomena in detail and explain the mechanism of whistler mediated beam stagnation.
It is difficult to get a real scale image of the solar system through lecture. A scale model is a classical and one of good solutions (e.g. Handa et al.2003, Handa et al.2008). Through this model, people living in or visiting to the city can physically understand the scale of the solar system. This scale gives 1 cm for Earth's diameter and 115 m for 1 AU. However, some gadget is required to make it attractive for public citizens.
Optical and near-infrared observations of novae give us useful information for understanding the diversity of nova eruptions. Classical nova V1723 Aql was discovered by F. Kabashima and K. Nishiyama on 2010 September 11. We have conducted photometric and spectroscopic observations of V1723 Aql in both optical and near-infrared (NIR) wavelength regions since its discovery. The V-band decline time by 2 mag after the maximum, t2, was ~12 d. The apparent Fe II emission lines were also seen in the optical spectra. The Rc- and Ic-band light curves exhibited rapid declines (0.16 mag d−1 in Rc) 20 days after the visual maximum, while the NIR (J, H, and Ks) showed slow decline rates (~0.07 mag d−1). This rapid reddening suggests that dust particles formed during the very early phase of the expansion in V1723 Aql.
Results of our experimental investigation on the ozone zero phenomenon suggested us the importance of the electrode surface condition. This means that the main cause of the phenomenon, that is, temporal decrease of ozone concentration at the outlet of DBD type ozone generator and the recovery characteristics from the phenomenon are considered as the surface reaction process, which are influenced strongly by the surface condition. The surface condition is never constant during the ozone generation and varies gradually or remarkably with time depending on the experimental conditions. Therefore we have been continued to make clear the cause of the phenomenon, for example, the reproducibility of the phenomenon, using new electrodes and together with the surface analysis technique etc. In this paper, we describe on the above results and discussion.
The theory of particle diffusion in an electrostatic turbulent plasma is formulated by applying the direct-interaction approximation (DIA) to subensemble-averaged functions instead of conventional ensemble-averaged ones. This theory approximately incorporates the Lagrangian description into the DIA through decorrelation trajectories. The running diffusion coefficient is shown to be calculated by solving a nonlinear ordinary differential equation together with an equation for decorrelation trajectories and by averaging initial conditions at the starting point of trajectories.
An experimental study is carried out to clarify the mechanism of the ozone zero phenomenon. Temporal variations of both the discharge characteristics and the metallic electrode surface in the ozone generator are investigated by the Lissajous figure method and Auger electron spectroscopy (AES), respectively. The AES results suggest that a number of oxygen atoms penetrate into the stainless-steel electrode owing to the exposure to ozone. Such a surface change would result in the temporal variation of the discharge characteristics of the generator.
The poloidal electric field generated by electron-cyclotron resonance heating is investigated for a tokamak plasma in the collisionless regime. This poloidal electric field is calculated by solving an adjoint equation to the linearized Fokker-Planck equation with a quasi-linear diffusion term. It is found from this calculation that the magnitude and the sign of the poloidal electric field depend strongly on the values of the inverse aspect ratio, the poloidal angle of the absorption point, the parallel velocity of resonant electrons normalized by the thermal velocity, and the strength of the relativistic correction to the resonance condition.
Dome Fuji is potentially one of the best astronomical sites in Antarctic plateau. We have a plan to build a 2-m class infrared telescope at Dome Fuji, and have been evaluating the site since the 2006/2007 Antarctic summer. We present the outline of a 2-m class telescope project and some results of our SODAR measurements.
This study aimed to evaluate the efficacy and toxicity of concurrent chemoradiotherapy as a primary treatment modality for larynx preservation in patients with stage two squamous cell carcinoma (SCC) of the glottic larynx. Between February 2000 and August 2003, a total of 20 patients received concurrent chemoradiotherapy. Carboplatin was given intravenously once a week during the period of radiotherapy. The weekly carboplatin dose was based on the area under the curve 1 to 1.25. Uracil–ftegafur (UFT) was given in a daily oral dose of 300 mg as tegafur. Radiotherapy was delivered five days a week using a once-daily fractionation of 2.0 Gray (Gy), to a total dose of 66–72 Gy. The three-year overall survival rate with larynx preservation was 100 per cent.
Concurrent chemoradiotherapy with carboplatin and UFT for stage two SCC of the glottic larynx was safe and effective in improving local control with larynx preservation.
In January 2003, two cases of Legionnaires' disease associated with a ship's cruise were registered in the database of National Epidemiological Surveillance of Infectious Diseases. A 70-year-old male heavy smoker with mild emphysema contracted the disease during a cruise. Legionella pneumophila serogroup (sg) 5 was isolated from the patient's sputum and the ship's indoor spa. The isolate from the spa matched the patient's isolate by genotyping performed by pulsed-field gel electrophoresis (PFGE). The second case was in a 73-year-old female. During epidemiological investigation, a third case of Legionnaire's disease in a 71-year-old male was subsequently diagnosed among passengers on the same ship on the following cruise. Environmental investigation revealed that porous natural stones (Maifanshi) in the filters of the spas had harboured L. pneumophila, a phenomenon which has not been reported except in Japan. This is the first documented evidence of L. pneumophila sg 5 infection on a ship and of porous stones as a source of Legionella infection.
The particle diffusion in a stochastic magnetic field is investigated by using the functional integral method. With the ensemble average of a functional representation to a kinetic equation over the fluctuating magnetic field and the random variables modeling the Coulomb collisions, a closed set of equations for an ensemble-averaged distribution function and a response function to an infinitesimal external perturbation is derived within the framework of the direct-interaction (DIA). By using the Markovian approximation to the equation for the response function, the cross-field diffusion coefficients are found to be obtained from nonlinear ordinary differential equations. Explicitly calculated diffusion coefficients for various parameters are also shown in the shearless and sheared configurations.
The characteristics of 1 MeV electron irradiated GaAs solar cells grown on GaAs and Si substrates are studied under dark and AM 0 conditions. The short circuit currents (Isc) for GaAs/GaAs cell and GaAs/Si cell have been decreased at higher fluences. The degradation rate of Voc and Pmax for GaAs/Si is slower than that of GaAs/GaAs at the fluence 1×1016 cm−2. This is due to the high radiation resistance of saturation current. It has been due to slow generation of arsnic vacancies related defect (VAs) in the GaAs/Si solar cell, which is determined by photoluminescence analyses and deep level transient spectroscopy.
We report estimates for the extragalactic background light (EBL) in the K band (2.2 μm), obtained by the integration of galaxy counts down to K=25 mag in the Subaru Deep Field (SDF, 2′ x 2′). We have obtained deep galaxy count data by using the 8.2m Subaru telescope, with a total integration time of 10 hours and an average seeing of about 0.4 arcsec. The 5-sigma limiting magnitude is K=23.5, and 350 objects are detected brighter than this magnitude. There has been a significant discrepancy between previous K-count observations, probably because of the systematic uncertainties in the completeness correction. To overcome this problem, we have paid special attention to selection effects and completeness corrections, with realistic theoretical galaxy models taken into account consistently. The faint-end slope is significantly flatter than some earlier observations of K counts, and our results suggest that the bulk of the extragalactic light in this band has been resolved as discrete sources. We estimate the value of the EBL flux obtained from the integration of our counts as 9.8 ± 1.0 nWm−2 sr−1.
Transport equations are investigated for a cylindrical plasma in the presence
of electrostatic fluctuations. In a weakly turbulent regime, the transport matrices
that relate the anomalous particle and heat fluxes and the parallel current to
the thermodynamical forces are determined by employing drift-kinetic and gyrokinetic
orderings for the electrons and ions. The calculation is based on the kinetic
equations for the ensemble-averaged and fluctuating distribution functions. The
crucial difference with previous works is the inclusion of an extra term in the drift-kinetic equation for the fluctuating electron distribution function. This extra term,
which arises from the ensemble-averaged first-order (in a Larmor radius expansion)
electron distribution function, leads to the Ware pinch components of the particle
and heat fluxes and a correction to the Ohmic current. Furthermore, Shaing's
ansatz, which was introduced in the synthetic theory of anomalous and neoclassical
transport, is shown to be connected with this extra term in the context of
a turbulent plasma, and the physical meaning and the validity of this ansatz are
revealed. In drift-wave turbulence, the transport matrices, expressed in an implicit
form by considering the frequency of fluctuations as a parameter, are rewritten
in an explicit form by determining its frequency through the dispersion relation.
The Onsager symmetry is shown to be broken for this explicit form of anomalous
transport matrix.
A synthetic theory of neoclassical and anomalous transport in a weakly
turbulent tokamak plasma is presented. The neoclassical effect on the anomalous
particle and heat fluxes and the parallel current in the presence of electrostatic
fluctuations is investigated using the kinetic equations for the ensemble-averaged
and fluctuating distribution functions. It is found in the drift-kinetic and gyro-kinetic orderings for electrons and ions that the Ware pinch components of the
anomalous particle and heat fluxes and the parallel current are sensitive to the
toroidal effect, although the other components of particle and heat fluxes are little
influenced. In the banana regime, these Ware pinch components and the anomalous
parallel current are shown to be significantly reduced when the condition
[mid ](ω − ωE)/
k∥ve[mid ] < (2ε)1/2
is satisfied, where ω and k∥ are the frequency and the
parallel wavenumber of fluctuations, ωE is the drift frequency due
to the radial electric field, ve is the thermal velocity for
electrons and ε is the inverse aspect ratio. Interpolated formulae that can be used
throughout all collisonality regimes are also obtained for the Ware pinch components and the
anomalous parallel current.
The electrical conductivity of nc-Si films grown from SiF4 and H2 with constant arsenic doping rises from 10-5 to 10 Scm-1 as the thickness rises from ˜ 0.1 to 1 μm. This variation demonstrates the strong influence of film structure on conductivity. We show that the conductivity of undoped nc-Si films of constant thickness can be varied by adding SiH4 to the SiF4 and H2 source gas.
We annealed dispersions of microcrystalline Si in amorphous silicon by heating to 550 °C. The dispersions had been deposited by plasma-enhanced CVD from SiF4 and H2 at 250 to 290 °C. By X-ray diffraction and Raman scattering we observe an increase in crystal size and volume fraction. The electron mobility, measured by the Van der Pauw method, also was raised to a highest value of 91 cm2V−1s−1 at the electron density of 7.6×1017 cm−3.
As a new dielectric layer for magneto-optical disks, we have developed AlGeN films prepared by the reactive sputtering method. The deposition rate, internal stress, and refractive index were investigated as functions of the sputtering parameters.AlGeN films were found to be superior in these points: high deposition rate, low internal stress (<1.5×109 dyne/cm2), and high refractive index (>2.4).
To evaluate dynamic characteristics and reliability, magneto-optical disks with TbFeCo double layer sandwiched by AlGeN layers were prepared on the polycarbonate substrate. Those disks had high carrier-to-noise ratio (C/N) even for 0.7 6 μm recording bit length. The acceleration test at a temperature of 60°C and a relative humidity of 90% was carried out. The defect error rate remained constant up to 2000 hours.
High reliability and good dynamic recording characteristics of the magneto-optical disk can be achieved by use of the AlGeN dielectric films.
Conventional selected area diffraction patterns as obtained in the TEM present difficulties for identification of materials such as asbestifonn minerals, although diffraction data is considered to be one of the preferred methods for making this identification. The preferred orientation of the fibers in each field of measurement, and the spotty patterns that are obtained, do not readily lend themselves to measurement of the integrated intensity values for each dspacing, and even the d-spacings may be hard to determine precisely because the true center location for the broken rings requires estimation. To overcome these problems, we have implemented an automatic method for diffraction pattern measurement. It automatically locates the center of patterns with high precision, measures the radius of each ring of spots in the pattern, and integrates the density of spots in that ring.
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