ON-LINE DETERMINATION OF SINGLE PARTICLE SIZE AND DENSITY IN THE 5 - 100NM DIAMETER RANGE

PROPOSED HERE IS A DIAGNOSTIC METHOD FOR THE ON-LINE, SEMI-CONTINUOUS DETERMINATION OF THE SIZE AND DENSITY (G/CM(3)) OF INDIVIDUAL PARTICLES IN THE 5 NM TO 100 NM SIZERANGE. THIS IS ACCOMPLISHED THROUGH A DOUBLE SIZE SPECTROMETRY SYSTEM. PARTICLES ARE FIRST SIZED BY THEIR STOKES DIAMETER, AND THEN SIZED BY THEIR AERODYNAMIC DIAMETER. THE FIRST MEASURE, NAMELY THE STOKES DIAMETER SIZING, GIVES THE GEOMETRIC DIAMETER OF THE PARTICLE FOR ROUND PARTICLES. THE SECOND MEASURE, THE AERODYNAMIC SIZING, IS DEPENDENT ON PARTICLE DENSITY AS WELL AS STOKES DIAMETER. THE RESULT IS A DISTRIBUTION OF PARTICLE DENSITIES AT EACH SELECTED STOKES DIAMETER. THE STOKES SIZING IS DONE BY AN ELECTRICAL MOBILITY SEPARATION, THE AERODYNAMIC SIZING IS DONE USING A SINGLE-STAGE HYPERSONIC IMPACTOR. THE ELECTRICAL MOBILITY SPEARATION PRODUCES MONODISPERSE PARTICLES OF KNOWN STOKES SIZE WHICH ARE SAMPLED BY THE IMPACTOR. THE AERODYNAMIC SIZE FOR PARTICLE CAPTURE IS VARIED BY ADJUSTMENT OF THE IMPACTION PLATE POSITION. SINCE PARTICLES ARE SINGLY CHARGED, THE RATE OF PARTICLE CAPTURE IN CAN BE MEASURED ON-LINE USING AN ELECTROMETER. THE SYSTEM IS EFFECTIVE OVER THE 5 TO 100 NM DIAMETER RANGE.