Development of Charge-to-Radius Ratio Measuring Apparatus for Submicron Particles

A preliminary study was made to develop a charge-to-radius measuring apparatus for submicron particles. One intended purpose of this apparatus is its use as the sensor of outlet particles in feedback controlled electrostatic precipitators. The amplitude of the motion of submicron charged particles inside a sine wave electric field, determined by the value of q/a, was measured optically by a combination of slits and a photomultiplier tube. Several types of slit configuration were tested to improve the signal-to-noise (S/N) ratio of the light signal from the particle. The S/N ratio improves as the area of slit opening is reduced to eliminate background light noise. The amplitude measurement was made with parallel slits by detecting the maximum velocity of the particle. at the crest of the electric field. The accuracy of the amplitude measurment was confirmed by other experiments.