Fig.11 shows the space charge and diffusion precipitates of ions as a function of ion flow rate. Positive and negative ion precipitates due to space charge and diffusion effects ranged from 92 to 97 % and 91e97 % for ion flow rates in the range of 1e5 L/min. Higher ion flow rates resulted in further reducing the space charge and diffusion precipitates of ions. Figs. 12e14 show the time variations of outlet ion concentration with collection voltage at different ion flow rates. For this study the collection voltages varied from 0 to 45 V, the ion flow rates from 1 to 5 L/min and the times of measurement from 0 to 100 s. It was found in Figs. 12e14 that the concentration of positive ions was more stable than that of negative ions. This was because a negative ion had a higher electrical mobility than a positive ion due to a negative corona in the corona discharge ionizer has much higherdensity of free electrons compared to a positive corona, perhaps a thousandth of the electron density, and a hundredth of the total number of electrons. However, the electrons in a positive corona were concentrated close to the surface of the curved electrode in region of high potential gradient; however, the electrons in a negative corona many of electrons are in the outer lowerfield areas[17]. Increasing the collection voltage resulted in the decrease of the ion number concentration at the collector outlet. Fig.15 shows the variation of outlet ion concentration with collection voltage at different ion flow rates. Low ionflow rate and high collection voltage resulted in a decrease in the number concentration of ions at the collector outlet. For positive and negative ions, the ion number concentration at the collector outlet decreased to about 0 at collection voltages greater than 5, 20, and 40 V for ionflow rates of 1, 3, and 5 L/min, respectively.