Results for “ISS Program”

DOE OSTI2022

AMS Thermal Cooling System (Final Report)

The Alpha Magnetic Spectrometer (AMS) is a U.S. Department of Energy-sponsored particle physics experiment on the International Space Station (ISS). AMS is exploring some of the most fundamental questions in physics such as understanding dark matter, antimatter, the origin of cosmic rays and their characteristics as well as searching for new physics phenomena in the universe. It has recorded more than 200 billion cosmic rays since its launch in May 2011. Over time, anomalies associated with the dedicated cooling system of the AMS Silicon Tracker system were observed, leading to the discovery of progressive deterioration in the functioning of the cooling system's four redundant pumps. The Tracker is crucial to the scientific mission of AMS, as it is the only subdetector that can distinguish matter from antimatter. This report details the successful program of work for the installation of the Upgraded Tracker Thermal Pump System (UTTPS) on AMS. This program included: identifying the root cause of deterioration in the original pumps; design, production, testing, and integration of the new UTTPS cooling system; launch of the UTTPS to ISS; installation of the UTTPS in AMS across a series of four complex extra-vehicular activities (EVAs); and establishment of a dedicated Flight Simulator Laboratory to test the performance of the UTTPS under various thermal conditions. This program was critical to the success of the AMS experiment, and its successful completion will enable AMS to continue taking data through 2030.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Quantitative investigation of sooting dynamics in droplet combustion using an automated image analysis algorithm

This paper reports an image analysis approach using a newly-developed open-source program to extract quantitative measurements of soot volume fraction (SVF) from digital video images of burning n-heptane droplets. The automated program developed in this work can analyze images of fixed and untethered droplets to quantify sooting dynamics. The images analyzed in the program were taken from experiments carried out in the Multi-user Droplet Combustion Apparatus (MDCA) onboard the International Space Station (ISS). In these experiments, video imaging of burning droplets was obtained using backlighting by a laser diode with a wavelength of 653 nm. Here, the light was collimated before it passed through the droplet and soot-containing region, after which the light was then attenuated and projected onto the camera’s sensors. This technique facilitates the measurements of SVF based on the principles of the full field light extinction method (FFLEM). The measurements provide quantitative data that reveal the sooting dynamics of liquid fuels during droplet combustion processes. The analyses of a soot-attenuating image (ISS n-heptane, untethered droplet) at an instant during the burning show that the SVF distribution has a peak at the soot shell location. It then decreases due to soot oxidation when the location is further away from the burning droplet. Regarding temporal effects on the maximum SVF (SVF max ), results show that SVF max first increases after the burning is initiated until a peak value is reached, after which SVF max decreases. The SVF max values identified in this study for n-heptane are quantitatively consistent with previously reported values for fiber-supported droplets and are reached relatively early in the burning history. n-Heptane images are also analyzed to show the effects of initial droplet sizes on the maximum soot volume fraction. Results show that SVF max decreases with increasing initial droplet size, which is consistent with visual observations of less soot formed and dimmer flame brightness as Do increases.

42 ENGINEERING↗