Gamma-ray attenuation for measuring cryogenic slush mixture density

Abstract

Gamma-ray attenuation is used to measure cryogenic mixture density. Parameters are optimized for specific space application. A simple error formula is established. The feasibility of the measurement is demonstrated. An automatic measurement device is built.

Density determination of slush nitrogen by the improved capacitance-type densimeter

“…(8) and (9) are impossible to be obtained, the method of magnitude analysis is employed here to evaluate the interference voltages, and the magnitudes of the capacitances are determined by measuring with the LCR meter. The load capacitance C X , namely the capacitance of the densimeter, is generally about 1 pF for the non-differential type, and less than 5 pF for the differential type, while C KN and C NG are usually larger than 30 pF, much larger than C X .…”

“…Due to the reflection of microwave by the inner wall of dewar, the wave-absorbent material is required to improve the measurement accuracy. Carapelle and Collette [8] developed a densimeter using gamma-ray attenuation to measure the densities of cryogenic slush fluids for space application, and the relative error for slush nitrogen density is within ±5.8%. However, it is not suitable for the radioactive substances and not very safe because of the radioactivity.…”

Capacitive gas-phase detection in liquid nitrogen

“…Current measurement systems for cryogenic environments use gamma-ray-based (Carapelle and Colette, 2005), microwave-based (Ohira, 2004), radio-frequency-based (Filippov et al, 2013), resistive, or capacitive (Jiang and Zhang, 2011) principles. Some of them intrude into the volume under investigation, and some can lead to a local heat input or other parasitic effects (Mukhopadhyay, 2010).…”

“…Among them, capacitive sensors promise a high potential to not only determine the position of the surface of a liquid phase (i.e. the position of the liquid-to-gas interface), but to also be costefficient, simple, and to show fast reaction times (Carapelle and Colette, 2005;Medeova et al, 1998;De Kerpel et al, 2013). They neither disturb the liquid movement nor do they heat the liquid.…”