The present paper describes a compact lidar system which is equipped with a high-power pulsed-laser-diode and a 30cm-diam. telescope. A photomultiplier with a high-speed data accumlator and a micro-computer are used for control and data processing. Field tests were carried out for measuring vertical profiles of suspended particles above congested roads during the winter season. High concentration of suspended particles was found up to an altitude of about 300m.
Considering the moisture that exist in the atmosphere, the water is thought to be complexly connected with the degradation process of polymeric materials due to the partial discharge. Therefore, in this paper, investigation was done from the standpoint that water has effects on the molecules degrading the polymer (i. e. the active molecules for the degradation). The degradation tests were carried out by using the parallel plate electrode system. High frequency potential was applied to the sample (Polyethylene), the particular atmospheric conditions having been established by appropriate mixture of N2, O2 and H20. The following results were obtained in respect to the measurment of the weight change of the samples, the inception voltage and the discharge magnitude by Lissajous's figure. In the N2+H2O atmosphere, the active oxygens were generated due to the discharge similar to the N2+O2 atmosphere, but the amount of generation per discharge magnitude was approximately 1/3 lower than in the N2+O2 atmosphere. In the case of the N2+H2O+O2 atmosphere, the water molecules had three types of degradation effects to the polymer corresponding to the enclosed density of the oxygen, namely the acceleration, inhibition and both of the effects.