The AAC may be thought of as translating the DMA into a rotating frame, where the electrical force on the particles is replaced by a centrifugal force. Particles are carried along the classifier by a sheath of clean air. The rotation of the classifier imparts a centrifugal force onto the particles, opposed by their drag force in air.
Particles which are larger than the selected diameter adhere to the outer wall of the classifier, those smaller than the target size exit with the excess sheath flow, particles at the selected diameter exit through the sample port.
Since the only forces acting on the particles are due to their mass and drag (i.e. aerodynamic diameter), charging is not required and charge state has no effect on classification.
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