isokinetic sampling

in atmospheric chemistry
https://doi.org/10.1351/goldbook.I03286
A technique for collecting airborne particulate in which the sampling device has a @[email protected] efficiency of unity for all sizes of particles in sampled air, regardless of wind velocity and direction of the instrument. The air stream entering the collector has a velocity (speed and direction) equal to that of the air in the gas stream just ahead of the sampling port of the collector.
Source:
PAC, 1990, 62, 2167. (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2198 [Terms] [Paper]