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It was conflrmed that light air ions have positive in∞uence on human health. For its appraisal it is necessary to know the concentration of air ions and air ion mobility spectrum. This spectrum is usually found out using the saturation characteristic measurement with a ger- dien tube; another design option consists in the aspiration condenser with a segmented inner electrode. The second method is faster, but the resolution of air ion mobility spectrum shows worse characteristics.. This paper deals with the mathematical analysis and numerical model- ing of saturation characteristic evaluation for this aspiration condenser with a segmented inner electrode. Using a combination of both methods may increase the resolution of air ion mobility spectrum, and the progress of measurement is still better than with the gerdien tube solution. The presumption that ions contained it the air have signiflcant in∞uence on living organisms has been discussed in a large number of scientiflc papers with a focus on the problem of concrete efiects of ions on bacteria, animals, and humans (1{3). Light and negative ions feature positive efiects on the human organism, whereas their heavy and positive counterparts bring about negative impact. It was shown by N. I. Goldshtein (3) that the complete absence of negative air ions in the inhaled air is fatal to animals. Any evaluation of air ions and their impact on the human organism is only made possible after and on the basis of air ions concentration measurement and air ions spectrum mobility. One of its methods is based on measurement using the aspiration capacitor. In a simple aspiration condenser | gerdien tube the internal electrode is not divided into several segments. This method will be modeled saturation characteristics for the natural spectrum of negative air ions measured in (4). Here, the disadvantage consists in considerable time consumption inherent with the measurement of air ions spectrum. However, if an aspiration condenser with a segmented inner electrode is applied, the pace of measurement can be substantially accelerated. We will obtain an estimation of the air ions spectrum in the given interval, whose accuracy can be further advanced by measurement at several voltages. For the purpose, saturation characteristics will be modeled again of individual segments of the aspiration condenser inner electrode. 2. THE ASPIRATION METHOD PRINCIPLE The basic principle of the aspiration method is shown in Fig. 1 on an elementary aspiration con- denser | gerdien tube; the principle (model) was taken over from (1) and (5). Here, it holds that d1 | inner electrode diameter, d2 | outer electrode diameter, L | length of gerdien tube, vx | air ∞ow velocity, \+" | positive air particle (ion), \i" | negative air particle (ion). The gerdien tube consists of two electrodes. There is an electric fleld between the inner electrode (the collector) and the outer electrode. The fleld is imposed by voltage source U. The air mass with ions is actuated by a fan through the gerdien tube. Negative ions in the electric fleld impact the collector, and the current produced is measured by an electrometer. The measured current is proportional to air ion concentration (2). By means of the change of polarity it is also possible to measure positive air ions. |
