| Popis: |
Atomization of an aqueous suspension of 0.8 μm polystyrene particles produces highly charged aerosols. The values of the absolute mean charge unit | q | = 31 and the s.d. σ = 4.0 were obtained by charge distribution measurements. In order to neutralize the charges on aerosol particles to the values of | q | = 2.1 and σ = 2.6 given by Boltzmann's equilibrium relationship, a bipolar ion atmosphere was created by a.c. corona discharge between needle point and orifice plate electrodes. Electroneutrality of the ionic cloud was found for one value V0, of the applied potential V, which depends upon the point-to-plate distance d, and the air velocity through the orifice v. When V V0 the sign was positive. By exposing 0.8 μm aerosol charged particles to a bipolar atmosphere, the residual particle charge reflected the same behaviour as reported above. The electroneutrality was attained for V0 = 2350 V, d = 2 mm and v = 200 m/sec. For low and higher values of V0 the aerosol charge assumed a negative or positive value. respectively. The behaviour of the aerosol neutralization with ions created by a.c. corona is similar to the neutralization by α disintegration, where electroneutrality is attained when the source plane-to-aerosol distance corresponds to the Bragg's maximum range in air. As expected, aerosol neutralization was also attained when a bipolar atmosphere was created by two ionizers facing each other, in which the needle electrodes generated d.c. positive and negative corona discharges. |
