One of several wind tunnels operated by Arizona State University at the Planetary Aeolian Laboratory at NASA Ames Research 
Laboratory, Moffett Field, CA, Building N242. This wind tunnel is no longer in operation.

A small portable wind tunnel used for low-gravity and reduced-pressure tests. It consists of two concentric cylinders
constructed of clear Lexan plastic, each 30 cm deep. The outer cylinder is 60 cm in diameter and the inner cylinder is 40 cm
in diameter; the space between the cylinders is the test section. The inner cylinder is spun at speeds of up to 3000 rpm by 
a variable-speed motor driving a belt-and-pulley arrangement, which causes an airflow between the cylinders. Instrumentation
consists of a tachometer, which measures the inner-cylinder rotational speed, and an accelerometer which measures the gravity.
The tunnel has been used onboard the NASA KC-135 0g test aircraft to obtain particle thresholds at 0-1.8 g. This information
provided verification of the equations used to correct for the difference between thresholds obtained at Earth gravity and
those which would be obtained at martian or other gravity levels. The CWT also provided a convenient means of measuring
the interparticle force, which becomes the predominant force resisting entrainment at 0g. This tunnel has also been used in 
the vertical gun vacuum chamber (VGCG) to obtain particle thresholds as low as 15 mbar. This capability is especially useful
when only a small amount of material is available for testing, because the particles are confined in the closed system and 
not dispersed outside the tunnel, as is the case with MARSWIT. Threshold information is obtained primarily visually, with 
videotaping of some of the runs for later analysis.