Aerosol particle charge and size analyzer

Claim 1

A method of determining the charge and aerodynamic size of a particle, comprising the steps of: (a) propagating an acoustic field on a directionalized first axis at a given location, (b) driving a gaseous carrier stream carrying particles of indeterminate size and charge, (c) directing said laden carrier stream into said acoustic field at a directionalized second axis transverse to said first axis to produce a difference between the motion of the particle and the motion of the gaseous carrier stream, (d) propagating a directionalized electrical field at the same location as said acoustic field to produce a unidirectional drift velocity on the particle which is a function of the charge and polarity of said particle, (e) and monitoring said particle to determine the quantum of said difference and of said unidirectional drift velocity as a measure of its charge and aerodynamic size.

Claim 2

A method of determining the charge and aerodynamic size of a particle, comprising the steps of: (a) propagating an acoustic field on a directionalized first axis at a given location, (b) driving a gaseous carrier stream carrying particles of indeterminate size and charge, (c) directing said laden carrier stream into said acoustic field at a directionalized second axis transverse to said first axis to produce a difference between the motion of the particle and the motion of the gaseous carrier stream, (d) propagating a directionalized electrical field at the same location as said acoustic field to produce a unidirectional drift velocity on the particle which is a function of the charge and polarity of said particle, (e) and monitoring said particle to determine the quantum of said difference and of said unidirectional drift velocity as a measure of its charge and aerodynamic size.

Claim 9

An apparatus for determining the size and charge of a particle in a fluid suspension, comprising: means forming a chamber, means for directing a stream of fluid in which particles to be measured are entrained into said chamber, an acoustic transducer for generating an acoustic field within said chamber, first and second electrode elements disposed opposite one another for generating an electric field within said chamber, said means forming said chamber having windows for admitting laser beams into said chamber and for enabling light scattered by the particles to exit said chamber, and laser actuated detecting means for projecting laser beams through said windows and for detecting the scattered light radiations which are a function of particle size and charge.

Claim 10

An apparatus for determining the size and charge of a particle in a fluid suspension, comprising: means forming a chamber, means for directing a stream of fluid in which particles to be measured are entrained into said chamber, an acoustic transducer for generating an acoustic field within said chamber, first and second electrode elements disposed opposite one another for generating an electric field within said chamber, said means forming said chamber having windows for admitting laser beams into said chamber and for enabling light scattered by the particles to exit said chamber, and laser actuated detecting means for projecting laser beams through said windows and for detecting the scattered light radiations which are a function of particle size and charge.

Claim 20

An apparatus for determining the size and charge of a plurality of particles in an aerosol sample, comprising: a laser Doppler velocimeter including an acousto-optic modulator connected to produce a diverging beam pair, a beam focusing apparatus mounted to focus said diverging beam pairs to form a measuring volume of interference planes, a relaxation chamber into which said diverging beam pair is focused, means for establishing an air flow of said aerosol sample through said relaxation chamber substantially parallel to said interference planes, an active acoustic transducer connected to generate an acoustic field within said relaxation chamber transverse to said air flow, a passive acoustic transducer mounted to monitor said acoustic field within said relaxation chamber to produce a reference signal, first and second electrode elements mounted across respective ones of said active and passive acoustic transducers and connected to generate a pulsed electric field within said relaxation chamber simultaneously with said acoustic field, whereby particles in said aerosol sample within said measuring volume are moved by said acoustic field and said electric field thereby scattering light from said interference planes, means for focusing said scattered light from the motion of the particles, a photodetector mounted to sense said focused scattered light and thereby produce an electrical signal, a signal processor connected to receive said electrical signal from said photodetector and connected to said passive acoustic transducer to receive said reference signal, a size counter connected to said signal processor to generate particle size data, a charge counter connected to said signal processor to generate particle charge data, and program controlled means for accumulating said particle size data and said particle charge data.

Claim 21

An apparatus for determining the size and charge of a plurality of particles in an aerosol sample, comprising: a laser Doppler velocimeter including an acousto-optic modulator connected to produce a diverging beam pair, a beam focusing apparatus mounted to focus said diverging beam pairs to form a measuring volume of interference planes, a relaxation chamber into which said diverging beam pair is focused, means for establishing an air flow of said aerosol sample through said relaxation chamber substantially parallel to said interference planes, an active acoustic transducer connected to generate an acoustic field within said relaxation chamber transverse to said air flow, a passive acoustic transducer mounted to monitor said acoustic field within said relaxation chamber to produce a reference signal, first and second electrode elements mounted across respective ones of said active and passive acoustic transducers and connected to generate a pulsed electric field within said relaxation chamber simultaneously with said acoustic field, whereby particles in said aerosol sample within said measuring volume are moved by said acoustic field and said electric field thereby scattering light from said interference planes, means for focusing said scattered light from the motion of the particles, a photodetector mounted to sense said focused scattered light and thereby produce an electrical signal, a signal processor connected to receive said electrical signal from said photodetector and connected to said passive acoustic transducer to receive said reference signal, a size counter connected to said signal processor to generate particle size data, a charge counter connected to said signal processor to generate particle charge data, and program controlled means for accumulating said particle size data and said particle charge data.