Engineering topics

S Yoon

Publications and source records attributed to S Yoon.

5 records

NASA NTRS2023

The Coupling Between Tropical Meteorology, Aerosol Lifecycle, Convection, and Radiation, During the Clouds, Aerosol and Monsoon Processes Philippines Experiment (CAMP2Ex)

The NASA Cloud, Aerosol, and Monsoon Processes Philippines Experiment (CAMP2Ex) employed the NASA P-3, Stratton Park Engineering Company (SPEC) Learjet 35, and a host of satellites and surface sensors to characterize the coupling of aerosol processes, cloud physics, and atmospheric radiation within the Maritime Continent’s complex southwest monsoonal environment. Conducted in the late summer of 2019 from Luzon Philippines in conjunction with the Office of Naval Research Propagation of Intraseasonal Tropical OscillatioNs (PISTON) experiment with its R/VSally Ride stationed in the North Western Tropical Pacific, CAMP2Ex documented diverse biomass burning, industrial and natural aerosol populations and their interactions with small to congestus convection. The 2019 season exhibited El Nino and associated drought, high biomass burning emissions, and an early monsoon transition allowing for observation of pristine to massively polluted environments as they advected through intricate diurnal mesoscale and radiative environments into the monsoonal trough. CAMP2Ex’s preliminary results indicate 1) increasing aerosol loadings tend to invigorate congestus convection in height and increase liquid water paths; 2) lidar, polarimetry, and geostationary Advanced Himawari Imager remote sensing sensors have skill in quantifying diverse aerosol and cloud properties and their interaction; and 3) high resolution remote sensing technologies are able to greatly improve our ability to evaluate the radiation budget in complex cloud systems. Through the development of innovative informatics technologies, CAMP2Ex provides a benchmark dataset of an environment of extremes for the study of aerosol, cloud and radiation processes as well as a crucible for the design of future observing systems.

CAMP2Ex↗

NASA NTRS2023

Refinement of Transition-Edge Sensor Dimensions for the X-ray Integral Field Unit on ATHENA

At NASA Goddard Space Flight Center, we have previously demonstrated a kilo-pixel array of transition-edge sensor (TES) microcalorimeters capable of meeting the energy resolution requirements of the future X-ray Integral Field Unit (X-IFU) instrument that is being developed for the Advanced Telescope for High ENergy Astrophysics (ATHENA) observatory satellite. The TES design in this array was a square device with side length of 50 μm. Here, we describe studies of TES designs with small variations of the dimensions, exploring lengths, parallel to the current direction, ranging from 75μm to 50μm and widths, perpendicular to the current direction, ranging from 50μm to 15 μm. We describe how these changes impact transition properties, thermal conductance and magnetic field sensitivity. In particular, we show that using a TES with a length of 50μm and width of 30μm may be a promising route to reduce the maximum time-derivative of the TES current in an X-ray pulse and reduce the sensitivity of the TES to magnetic field.

N A Wakeham↗

NASA NTRSDate not supplied

Effect of Space Radiation on TES Detectors Performance

The Athena mission and its X-IFU instrument (X-ray Integral Field Unit) will be positioned at the Sun-Earth Lagrangian point L1, where it will be subject to solar wind (low flux plasma of 95% protons and 5% alpha particles) with energy below 0.1 MeV, and to galactic cosmic rays and solar flares (energetic protons, alpha particles, and electrons) with energies up to hundreds of MeV for protons and the GeV for heavier ions. Some of these particles will go through the satellite and hit the focal plane assembly and hence the detectors. These detectors will be TES (Transition-edge sensor) microcalorimeters, flown for the first time in such an environment. In order to ensure the performance of this type of detectors throughout the duration of such mission, it is critical to study the impact of the radiation on their behavior. Indeed, although a lot of reference material exist for semiconductor detectors such as CCDs, little is currently known about the impact of radiation on TES detectors. These energetic events could cause local heating or damage to the detectors and affect their performance. In this work, we describe how we designed a test campaign to assess the impact of L1 radiation on TES detectors for Athena/X-IFU-like missions and present the results of the tests. Analyses includes assessing changes in the pulse shapes and energy resolution of the detectors measured at 55 mK after several radiation dose steps performed at 4 K.

Sophie Beaumont↗

NASA NTRSDate not supplied

Long Term Performance Stability of TES Detectors

We are developing superconducting transition-edge sensor (TES) microcalorimeter arrays for a variety of applications such as ground-based laboratory astrophysics experiments and next generation space-based X-ray missions. These detectors can provide X-ray spectral information with an unprecedent resolution of ~2 eV at 6 keV and have been selected for the X-ray Integral Field Unit (X-IFU) instrument of ESA’s large flagship mission Athena. To maintain detector performance over the lifetime of the mission, it is important to understand whether environmental conditions that the detector may be exposed to will affect its properties over time. This “aging” begins right after the array leaves the fabrication environment, with potential exposure to humidity, oxygen, or elevated temperatures which may affect the detector performance. In a few prior arrays we have observed increased fall times in the pulse shape and/or the introduction of anomalous low energy tails on the X-ray spectrum. This is thought to be an indication of “aging” on chips exposed to such conditions, causing e.g. changes in the absorber properties. In this contribution, we report on a systematic characterization of TES properties, before and after exposing the chip to various controlled temperature and humidity levels and assess the changes in the measured transition and pulse shapes, energy resolution, and spectral redistribution.

S Beaumont↗

NASA NTRSDate not supplied

Refinement of the Transition-edge Sensor Design for ATHENA X-IFU

The X-ray Integral Field Unit (X-IFU) instrument on the Advanced Telescope for High ENergy Astrophysics (ATHENA) is baselined to have 2376 transition-edge sensor (TES) microcalorimeter pixels in a single array. The required performance for X-IFU has been demonstrated on a kilo-pixel array of square TES’s with 50 m side length, and this is considered the baseline pixel design. However, over the last few years we have explored small modifications to this design in search of a globally optimized instrument performance. We have previously reported on investigations of extending the length of the TES’s and variations in the number of X-ray absorber support stems. Here we report on investigations of TES designs with a length of 50 m but narrower width. We will discuss the consequence of this on magnetic field sensitivity, resistive transition parameters, spectral performance, and ease of multiplexing. We will also discuss how the number and position of the absorber attachments influences the vibrational modes of the pixels, and the impact this may have on performance. Finally, we will present measurements of more substantial change options of our TES design, including more extreme TES geometries, the use of metal islands or etched holes in the silicon nitride membranes, and the position of wiring to minimize current-induced magnetic field effects. The exploration of all these changes to the design are not only useful for optimizing performance on X-IFU, but also guide our fundamental understanding of the key physics of TES microcalorimeters.

Nick Wakeham↗