- test chamber that does not require liquid coolant submersion
- cryogenic testing equipment
There is amajor need for cryogenic materials testing at extreme temperatures at or below -200°C, for example space applications such as exploration of the Moon, Titan, and Europa. Existing technologies which cool reliably and quickly use direct submersion in liquid nitrogen, which limits testing conditions. Indirect cooling methods provide cooling that is too slow and/or limited for practical tests.
This invention performs rapid cooling of mechanical testing equipment to extreme cryogenic environmental conditions without direct submersion in liquid coolant. Cryogenic liquid is introduced into an environment chamber via a series of unconnected, open channels, as shown in Fig. 1. Cooling is performed via evaporation, convection, and conduction into all parts of the test fixture simultaneously. The environment chamber is unsealed and placed at positive pressure to avoid moisture contamination, allowing for a large cryogen mass flow rate and improved cooling performance from a compact chamber with limited insulation. In order to control the temperature, ensure positive pressure, and prevent condensation of the atmosphere at extreme test conditions, a continuous flow of room-temperature high-purity gas is introduced adjacent to the sample. Using liquid nitrogen as a coolant, an uninsulated quartz glass test chamber with aluminum end caps reached minimum possible test conditions of -196°C in 26 minutes, measured via a thermocouple within the test sample.
Name: Shyamala Rajagopalan