Universal Scanning Mobility Particle Sizer for a measuring range from 8 to 1200 nm

Palas® U-SMPS systems work according to the principle of “electric mobility” of particles in the electric field and in ambient air, as described in ISO 15900:2000. Here, the particles in the aerosol are first brought into a neutral known charge equilibrium with known charge distribution (Bolzmann charge distribution) by different bipolar neutralizer systems (X-ray emitters, radioactive emitters) and then selected by size via the classifier column (Differential Mobility Analysis – DMA). The selected particles are detected and recorded using a counter (e.g., condensation particle counter or electrometer).

Particle-free enveloping air in the column carries the aerosol flowing in at the annular gap of the column to the opposite side of the column. At the same time, an electric field from the inner column outer wall to the inner center electrode displaces the particles horizontally to the electrode (capacitor). They drift after short acceleration with constant velocity and either reach the upper inner annular gap (exit to the counter) or are deposited at the electrode or carried out of the column via the enveloping volume flow and filtered off.

The change of the applied voltage at the electrode of the column (typically in the range of a few volts up to max. 10 kV) leads to different horizontal drift velocities in the column depending on the particle size and the number of charges on the particle. An “inversion algorithm” can be used to infer the particle size and concentration, as described in ISO 15900:2000. Instead of selecting individual particle sizes, the systems can display the size distribution and concentration in the set range in scan mode.

All settings can be accessed directly via the 7″ touch screens, also used for the initial graphical processing and enabling the first comparisons. Measured values and sensor data are immediately and continuously recorded.