Comparison of Different Methods for Determining the Air Ion Mobility Spectrum

Light negative air ions demonstrably exert a positive influence on the human organism. To assess their impact on the human body, we to know their mobility and related aspects. The spectrum is usually defined by measuring the saturation characteristic with a Gerdien tube; another option consists in using an aspiration condenser with a segmented inner electrode. A major problem affecting the methods outlined within the paper rests in the impact of measurement uncertainties and noise on the results. We propose a solution where the actual estimation of the air ion mobility spectrum is refined via combining analytical calculation and the numerical method of least squares. The Matlab-based simulation procedure reduces the number of measured polarization voltages, optimizes the dimensions of the internal electrode segments, and defines the impact of noise on the result. The simulation is compared with saturation characteristics measured in a faraday chamber.