Midinfrared Absorption Measurements of Nitrous Oxide in Ammonium Dinitramide Monopropellant Thruster

Abstract

The thermodynamic compensation law describing an empirical linear relationship between activation enthalpy and activation entropy has seldom been validated for amorphous solids. Here molecular dynamics simulations reveal a well-defined enthalpy-entropy compensation rule in a metallic glass (MG) over a wide temperature and stress range, spanning the glass transition induced by temperature and/or stress. Experiments on other MGs reproduce this law, suggesting that it applies universally to amorphous solids, so we extend it from crystals to amorphous solids. In the glassy state, the compensation temperature is found to agree with the thermal glass transition temperature T g ; whereas in the supercooled liquid region, the compensation temperature matches ∼ 1.4T g , at which the diffusion kinetics start to feel the roughness of the free-energy surface.

Combined tunable diode laser absorption spectroscopy and monochromatic radiation thermometry in ammonium dinitramide-based thruster

“…11 Temperature nonuniformity along the optical pathlength had been carefully evaluated and the cold-flow zone of the boundary layer led to 4.3% variation in temperature measurements, thus we considered gas flow in the cross-section of the chamber was uniform. 21 For temperature measurements of the inner wall, a monochromatic thermometry system was developed, consisting of a CCD camera mounted with a filter and a PC equipped with a data acquisition system including a frame grabber and system software. Measurements were conducted at position 1 and position 2, respectively, as shown in Fig.…”