The measurement of depolarized radiation for monitoring the mass concentration of particulates

Author

• Bruce E. Wilson, New Jersey Institute of Technology

Document Type

Thesis

Date of Award

9-30-1978

Degree Name

Master of Science in Electrical Engineering - (M.S.)

Department

Electrical Engineering

First Advisor

Harlan J. Perlis

Second Advisor

John W. Liskowitz

Third Advisor

W. H. Warren Ball

Abstract

The depolarization of backscattered polarized incident radiation which is expressed as a depolarization ratio was investigated as a means of monitoring the mass concentration of particles in stacks from coal-fired burners. This involved the design of an instrument that would detect small levels of radiation. Two methods were investigated. The first utilized a Gallium Arsenide laser and a silicon detector diode; the second was composed of a xenon flash lamp and a photomultiplier detector tube.

The relationship between the depolarization ratio and the mass concentration of diamond particles in the 0.01 gm/m³ to 0.5 gm/m³ was determined. Diamond particles in the Oμ-0.2μ, 0μ-0.5μ, 0.5μ-1.0μ, 1.0μ-1.5μ and 1.0μ-2.0μ size ranges suspended in water, ethylene glycol and benzene were used to evaluate the effect of size and refractive index ratios of 1.6, 1.7 and 1.8, respectively, on this relationship. The influence of such factors as optical path length and scattering of radiation off the walls on the depolarization ratio were also examined. In addition, relationship between the intensity of backscattered radiation measured at 167 degrees and the mass concentration of particles in suspension was investigated.

The results show that the depolarization ratio is dependent on the mass concentration of particles and the refractive index ratio. Isolation of the refractive index ratio effect is indicated by performing the depolarization measurements simultaneously at two different optical paths. The depolarization ratio was found to be independent of size variations in the 0.5μ-8.0μ range at a refractive index ratio of 1.6 and independent of size variations in the 1.0μ-8.0μ range at a refractive index ratio of 1.8. This is provided that the wavelength of incident radiation is comparable or smaller than the particles in suspension and scattering from the wall that is seen by the receiver is minimized.

Recommended Citation

Wilson, Bruce E., "The measurement of depolarized radiation for monitoring the mass concentration of particulates" (1978). Theses. 3581.
https://digitalcommons.njit.edu/theses/3581