Passive Cavity Aerosol Spectrometer Probe
PCASP is a wing-mounted aerosol probe that uses a standard PMS canister. Sample air enters the forward-facing inlet and decelerates by ~10x. Side-facing skarf tube provides suction for continuous flushing of the air to provide fast time response.
During cloud penetrations, the splash-breakup of cloud particles can produce large concentrations of spurious particles, and some of these can enter the PCASP air sample as a contamination. Internal diaphragm pump drives air flow through the optical cavity. Sample rate is ~1 cc/sec within a particle-free sheath flow of 15 cc/sec.
Alternate name: Passive Cavity Aerosol Spectrometer Probe with Signal Processing Package-200
Measurements Provided: Size distribution and concentration of aerosol particles ~0.1 to 3.0 micrometer diameter in 30 size bins. *Note: due to its flow system design, the PCASP is not suitable for operation above about 8 km altitude.*
Typical Sampling Rates: 10 Hz
Example(s) of Measurement: Two examples of differential size distributions from the FRAPPE project:
Size calibrations use monodisperse aerosols, including PSL (polystyrene latex) spheres or ammonium sulfate passed through DMA