Effects of air pressure on impulse coupling coefficient in air breathing laser propusion

Keeping the single pulse energy of CO2 laser constant, the impulse coupling coefficients in air-breathing laser propulsion are measured at different air pressure with a high precision impact pendulum system and the altitude characteristics are analyzed. The results indicate that the impulse coupling coefficient is about 3.5×10-4 N·s·J-1 with a fluctuation lower than 5%, when the air pressure ranges from 2.8×104 Pa to 1×105 Pa and the altitude from 0 to 10 km. When the air pressure is lower than 2.8×104 Pa and the altitude higher than 10 km, the impulse coupling coefficients drop apparently in terms of conic. At the pressure of 1×103 Pa and altitude of 31 km, the impulse coupling coefficient is only 9.7×10-5 N·s·J-1.