MEASUREMENTS OF THE REDUCED FORCE COEFFICIENTS FOR H-2, N-2, CO, AND CO2 INCIDENT UPON A SOLAR PANEL ARRAY MATERIAL, SIO2-COATED KAPTON, KAPTON, AND Z-93-COATED AL

The reduced force coefficients were measured for H-2, N-2, CO, and CO2 incident upon a solar panel array material, SiO2-coated Kapton, Kapto n, and Z-93-coated Al. The coefficients were determined by measuring b oth the magnitude and direction of the force exerted on the surfaces b y molecular beams of the gases. Measurements were made at angles of in cidence of 0 degrees, 25 degrees, 50 degrees, 75 degrees: and 85 degre es. The forces were measured using a torsion balance with the surfaces mounted on the end of the lever arm. The absolute flux densities of t he molecular beams were measured using a second torsion balance with a beam stop mounted on the lever arm that nullified the force of the sc attered molecules. Flux measurements were also made using the effusive method. Standard time-of-flight techniques were used to determine the flux-weighted average velocities of the molecular beams. These veloci ties ranged from 1670 to 4620 m/s. The overall uncertainty in the redu ced force coefficient measurements was estimated to be less than +/-10 %. These measurements were used to obtain the magnitude and direction of the flux-weighted average velocity of the scattered molecules, and also the flux-weighted translational kinetic energy of the scattered m olecules. Analysis of this information provided insight into the micro scopic details of the gas-surface interaction potential energy surface .