Pa In Air Research Articles

Electrical conduction of CeP2O7 and Ce0.95Yb0.05P2O7 at intermediate temperatures

Abstract Intermediate temperature proton conducting Ce0.95Yb0.05P2O7 and CeP2O7 samples are prepared and the conduction behaviors are investigated from 100 to 300 °C. The variation of conductivity with the pH2O or time is also studied. The highest conductivity of Ce0.95Yb0.05P2O7 is observed in dry air atmosphere at 300 °C to be 9.6 × 10− 5 S·cm− 1 and in wet air atmosphere (pH2O = 3.2 × 103 Pa) at 150 °C to be 3.3 × 10− 3 S·cm− 1. The log σ ~ log (pH2O) plot result shows that the conductivities increase linearly with increasing pH2O and reach 3.4 × 10− 3 S·cm− 1 with pH2O = 1.2 × 104 Pa in air at 100 °C.

空気中の強い衝撃波背後の発光特性 （第２報） 全放射発光の諸特性

This paper describes time-frozen measurements using a CCD camera system for total radiation behind strong shock wave in a shock tube. The measurements are carried out for the shock velocity range from 6.8km/s to 12.5km/ s at the initial pressure range from 13.33Pa to 133.3Pa in air. The experimental results are compared with the numerical ones. There is a relatively good agreement between the experimental and numerical results at 10km/s shock velocity at the initial pressure 13.33Pa, although some discrepancies appear at the other velocity range. It is found that the full width at half maximum of profile of the first-peak becomes narrower and the thickness of radiation front becomes broader, as the shock velocity increases at the lower initial pressure. At the higher initial pressure, there is a limitation of spatial resolution in the present experiment.

230 空気中の強い衝撃波背後における発光の時間分解画像分光計測

This paper describes the imaging spectroscopic technique applied to the experimental study of radiation emanating from strong shock waves in air. Shock velocity is about 11km/s and initial pressure is 13.3Pa in air. The spectral diagnostic system consists of an imaging spectrograph, a streak camera, a gated image-intensified CCD camera and a personal computer for data acquisition/processing. This spectral diagnostic system is capable of simultaneous wavelength-, intensity and time-resolved spectroscopic measurements in the nanosecond order. Wavelength range is chosen primarily to investigate the first negative band of N2+ and the second positive band of N2. Spectra with enhanced spectral resolution are obtained.

Design and calibration of a microfabricated floating-element shear-stress sensor

A microfabricated floating-element shear-stress sensor for measurements in turbulent boundary-layers is reported. Using surface micromachining of polyimide, a 500- mu m*500- mu m probe has been fabricated incorporating a differential-capacitor readout circuit. A model for the sensor response is described and is used for the design of an element to measure shear stresses of 1 Pa in air. The sensor is packaged for calibration in laminar flow, and electrical results obtained match the expected response. >

Effects of Glow Discharge Conditioning and Addition of Gases on Surface Flashover

The dc, ac (60 Hz), and lightning impulse (1.2/50 ?s) flashover voltages of solid insulators in high vacuum at a pressure of about < 10-6 Pa have been measured before and subsequent to conditioning with an ac (60 Hz) glow discharge at a pressure of 130 Pa. Sulphur hexafluoride, air, nitrogen, and hydrogen have been used in the glow discharge conditioning. Quartz, Pyrex glass, and Teflon insulators in the form of right angle cylindrical spacers sandwiched between a pair of planar stainless steel electrodes are employed. It has been found that the dc, the ac, and the lightning impulse flashover voltages of the insulators in vacuum are higher after conditioning with a glow discharge. The flashover voltage is also measured in the pressure range 10-6 - 5xl0-4 Pa prior to and after glow discharge conditioning. The flashover voltage increases in the pressure range 10-2 - 10-1 Pa only when sulphur hexafluoride is used. No pressure dependence is found in the range 10-6 - 10-1 Pa in air, nitrogen, and hydrogen when using a pair of stainless steel electrodes bridged by any one of the three dielectric materials. SF6 gives the highest surface flashover voltage compared to air, N2, and H2.