Impact Of Cryogenic Temperatures Research Articles

The Impact of Cryogenic Temperatures on the Hardness and Tribological Properties of Cobalt Alloys

The Impact of Cryogenic Temperatures on the Hardness and Tribological Properties of Cobalt Alloys

Impact of cryogenic temperatures on high-power semiconductor performance

Power electronics is necessary for the independent control of the stator windings of electric aircraft motors. The benefit of using liquid fuel to cool conductors to utilize their high current density has enabled power electronics to be cooled by proxy. While small scale semiconductors have been found to be degraded during operation at cryogenic temperatures, results for systems rated for high power cryogenic applications have not been explored as much. In this work we test the performance of IGBT power electronics from room temperature to 77 K, with a focus on temperatures expected for electric aircraft motors using liquid natural gas (LNG, BP about 120 K) as the cooling medium. In this work, the measure of performance was taken to be the ability to be turned on and off (switched) by an input signal provided by a function generator. We also tested the cold-start ability i.e., the lowest temperature in which the power inverter will start. The lowest cold-start temperature was measured as 140 K. Experimentally, we also observed that both conduction losses and switching loss from a low-power constant current with an operational frequency of 10 kHz were sufficient to allow the inverter to work down to 105 K (below the LNG boiling point).

Application of the ultrajet diagnostic method to assess the damage of carbon fiber-reinforced plastic under cooling conditions

This paper considers the possibility of using the ultrajet diagnostic for studying the strength properties of carbon fiber-reinforced plastics after cryogenic temperature impact. The method is based on the interaction of a high-speed liquid jet and a fine-dispersed abrasive with the coating to be diagnosed. Analysis of the experimental data revealed a decrease in the material’s strength after cooling in liquid nitrogen. The deterioration of the composite strength properties is explained by the decrease in the adhesive strength in the “fiber-matrix” system.

Static Performance of SiGe HBTs at Low Temperature

—This paper analyse is the impact of cryogenic temperatures for SiGe Heterojunction Bipolar Transistors (HBTs) base, realised in BiCMOS9 0.13μm industrial process. The use of these components in microwaves applications exposed to various temperatures is fundamental aspect to predict in precise way its electric characteristics. This paper investigates the temperature dependence from (170 K to 300 K) of DC, for NPN SiGe heterojunction bipolar transistors (HBTs) and notably modeling high performance Si/SiGe HBT for telecommunication and radar detection (>0.5THz) in low temperature (cryogenic temperature).