The transmittance and reflectivity of metal meshes made brass wire were measured in the far infrared region. these is very low wavelength region up to about 1.3 times mesh constant, but then increases steeply so that becomes a nearly perfect reflector beyond twice constant. This reflecting property excellent for reflection filter, compared with usual filters.

A far infrared spectrograph is described. The mounting of the Czerny-Turner type. radiation sources are a heated platinum strip used in short-wave region and high-pressure mercury lamp long-wave region. Golay cells with diamond or quartz windows as detectors. Holders for filters to eliminate reflection transmission samples designed convenient use. Special chambers provide optical paths long gas holders small solid samples. All parts system vacuum tank remote-controlled. Spectra automatically...

Pile-of-plates polarizers made of thin sheets polyethylene were constructed for use in a far-infrared spectrograph. The degree polarization with 15 is more than 97% except the spectral region which constructive interference light reflected from both surfaces sheet increases transmission s component and decreases polarization. 75% incident plane polarized light. Limitations due to decreased by combining two thicknesses. reflectivities filter grating, dispersion gratings, reststrahlen crystals...

The magnetospheric response to a solar wind impulse, geomagnetic sudden commencement, is studied using an MHD model of the coupled wind‐magnetosphere‐ionosphere system. This paper discusses propagation first signal launched by impulse and generation field‐aligned current that causes ground magnetic detected as preliminary (PI). It revealed PI excited enhanced Chapman‐Ferraro in magnetopause next turns magnetosphere along wavefront compressional impulse. finally converted via mode coupling...

Mode conversion to the fast magnetosonic wave by anisotropic ionospheric currents from a localized incident shear Alfvén is studied in detail, based on simple layered model inclusive of an conducting sheet (the E layer) and upper ducting layer under vertical, uniform ambient magnetic field lines. A horizontal profile electromagnetic intensity at shows wider spread than that due trapping layer. Since electrostatic electric dominant central region, eddy Hall current associated with generates...

The substorm mechanism is investigated by analyzing the numerical results obtained through use of recently refined magnetohydrodynamic model. After showing growth phase features, solution reproduces observed signatures a onset, including formation near‐Earth neutral line (NENL), earthward directed flow in plasma sheet, dipolarization, geosynchronous D deflection, development nightside field aligned currents (FACs), and electrojets ionosphere. onset triggered sudden collapse sheet successive...

A geomagnetic sudden commencement (SC) is studied numerically based on a model of buffeting the magnetosphere by solar wind density impulse. This paper treats two successive current systems in main impulse (MI) phase. The have different generating mechanisms. first generator appears behind wavefront compressional disturbance launched inertia mode generated free energy due to deceleration plasma flows. field‐aligned (FAC) excited through conversion from wave V gradient region. magnetospheric...

Abstract We performed 3‐D time domain simulation of geomagnetically induced currents (GICs) flowing in the Japanese 500‐kV power grid. The three‐dimensional distribution electric field (GIE) was calculated by using finite difference method with a electrical conductivity model constructed from global relief and map sediment thickness. First, we imposed uniform sheet current at 100‐km altitude sinusoidal perturbation to illuminate influence structured ground on GIE GIC. result shows that...

We developed, characterised, and verified an alignment method for the DESHIMA 2.0 instrument, ultra wide-band spectrometer operating between 200-400 GHz, at ASTE telescope. Due to ultra-wide bandwidth of 2.0, we require work across entire spectral range. Moreover, should be possible remotely, as on-site access is impractical. To fulfill these requirements mounted warm optics, consisting a modified Dragonian dual reflector system, on motor controlled hexapod. Crucial in procedure our sky...

A linear analysis of the Kelvin‐Helmholtz instability is performed by assuming that one plasma regimes (magnetosphere) separated a velocity shear layer zero thickness spatially nonuniform. The previous theories based on semi‐infinite uniform model with infinitesimally thin magnetopause showed wave growth due to exhibits monotonic increase for shorter frequency. This finding implies no monochromatic waves whose spatial scales are as large magnetospheric size generated instability. In...

Abstract From the global magnetosphere‐ionosphere coupling simulation, we examined formation of Sun‐aligned arc region and void (polar slot) under northward interplanetary magnetic field (IMF) with negative B y condition. In magnetospheric null‐separator structure, separatrices generated from two null points separators divide entire space into four types region, i.e., IMF, northern open field, southern closed field. ionosphere, are reproduced in distributions simulated plasma pressure...

Abstract In this paper, we try to elucidate the generation mechanism of field‐aligned current (FAC) and coexisting convection. From comparison between theoretical prediction state numerical solution from high‐resolution global simulation, obtain following conclusions about distribution dynamo, magnetic field structure along flow path that diverges Poynting flux, energy conversion promoting electromagnetic energy. The dynamo for region 1 FAC, which is in high‐latitude‐side cusp‐mantle region,...

Abstract We have developed a global simulation code which gives numerical solutions having an extremely high resolution. The substorm solution obtained from this reproduces the precise features of onset in ionosphere. It can reproduce that starts equatorward side quiet arc, two step development onset, and westward traveling surge (WTS) 2 min after initial brightening. Then, we investigated counter structures magnetosphere correspond to each event structure promoting is near‐Earth dynamo...

Behavior of fast-magnetosonic-mode MHD signals in the inner magnetosphere that are driven by impulsive eastward current is investigated as a model Pi2 signal at midnight. The treated an axisymmetric cold regime with dipole magnetic fields and has plasmaspheric structure Alfvén speed distribution. perturbation assumed to be axisymmetric. Numerical calculation revealed following: 1) induces plasmasphere virtual resonance oscillation; 2) compressional field confined near equator; 3) waveform...

The present paper deals with the transient behavior of MHD perturbations in inner magnetosphere induced by an impulsive localized eastward current (source current) as a model Pi2 pulsations magnetosphere. magnetospheric consists dipole magnetic field, plasmasphere, ionosphere Pedersen conductivity, and free outer boundary. source is at onset substorm wedge distributed around equatorial plane L = 10 ±2 hour longitudinal extent midnight. numerical results allow us to track variation expected...

The reflection and transmission spectra of ruby, pure α–Al 2 O 3 haematite (α–Fe ) were observed in the infrared region from to 200 µ. Six bands found for each compound accordance with conclusion factor group analysis, which predicts two polarized parallel c -axis four perpendicular -axis. By examining spectrum a polyethylene sheet polarizer, polarization character some beyond 17.5 µ was confirmed; but complete assignment six not tried because insufficiency data under due unfavorable...

Abstract We investigated the temporal variations and saturation of cross polar cap potential (CPCP) in Bastille Day storm event (15 July 2000) by global magnetohydrodynamics (MHD) simulation. The CPCP is considered to depend on electric field dynamic pressure solar wind as well ionospheric conductivity. Previous studies only conductivity due extreme ultraviolet (EUV) variations. In this paper, we dealt with changes attributable auroral caused enhancement inner magnetosphere owing energy...

During a great magnetic storm on Feb 11, 1958, fan-shaped aurora was photographed at Memambetsu, Hokkaido, Japan – the first and oldest photograph record of auroras observed in Japan, accompanied by many hand-made drawings, thus, portraying rare opportunity coexistence between images drawings. In fact, same portrayal reminds us red with white pillars during 1872 1770 storms. The sketches, photographs, spectral data revealed that glow were dominated auroral green lines, respectively. From...

Abstract Physics-based simulations are important for elucidating the fundamental mechanisms behind time-varying complex ionospheric conditions, such as potential, against unprecedented solar wind variations incident on Earth’s magnetosphere. However, carrying out an extensive parameter survey comprehending nonlinear density dependence of example, requires state-of-the-art global magnetohydrodynamic (MHD) simulations, which cannot be executed efficiently even large-scale cluster computers....

Ducted propagation of short‐period hydromagnetic waves in the upper ionosphere are studied based on a layered model including ducting ionospheric layer and an anisotropic conducting sheet ( E layer) under vertical, uniform ambient magnetic fields. Energy ducted wave is dissipated by Joule loss, Poynting loss due to shear Alfvén converted from fast magnetosonic Earth. The mainly contributes energy dissipation as far Pedersen conductivity not much smaller than Hall conductivity. Spatial...