Cryogenic Heat Transfer System

Disclosed herein is a cryogenic heat transfer system capable of transferring 50 W or more at cryogenic temperatures of 100.degree. K or less for use with cryocooler systems. In an embodiment, a cryogenic heat transfer system comprises a refrigerant contained within an inner chamber bound by a condenser in fluid communication with an evaporator through at least one flexible conduit, the condenser in thermal communication with the cold station of a cryocooler, and the evaporator positionable in thermal communication with a heat source, typically a radiation shield of a cryogenic chamber. A process to remove heat from a cryogenic chamber is also disclosed

Heterodyne Interferometer Angle Metrology

A compact, high-resolution angle measurement instrument has been developed that is based on a heterodyne interferometer. The common-path heterodyne interferometer metrology is used to measure displacements of a reflective target surface. In the interferometer setup, an optical mask is used to sample the measurement laser beam reflecting back from a target surface. Angular rotations, around two orthogonal axes in a plane perpendicular to the measurement- beam propagation direction, are determined simultaneously from the relative displacement measurement of the target surface. The device is used in a tracking telescope system where pitch and yaw measurements of a flat mirror were simultaneously performed with a sensitivity of 0.1 nrad, per second, and a measuring range of 0.15 mrad at a working distance of an order of a meter. The nonlinearity of the device is also measured less than one percent over the measurement range

A report on the laboratory performance of the spectroscopic detector arrays for SPIRE/HSO

We report the performance of the flight bolometer arrays for the Spectral and Photometric Imaging REceiver (SPIRE) instrument to be on board of the Herschel Space Observatory (HSO). We describe the test setup for the flight Bolometric Detector Assembly (BDA) that allows the characterization of its performance, both dark and optical, in one instrument's cool down. We summarize the laboratory procedure to measure the basic bolometer parameters, optical response time, optical efficiency of bolometer and feedhorn, dark and optical noise, and the overall thermal conductance of the BDA unit. Finally, we present the test results obtained from the two flight units, Spectroscopic Long Wavelength (SLW) and Spectroscopic Short Wavelength (SSW)

The Ariel payload electrical and electronic architecture: a summary of the current design and implementation status

Ariel is the M4 mission of the ESA’s Cosmic Vision Program 2015-2025, whose aim is to characterize by lowresolution transit spectroscopy the atmospheres of over one thousand warm and hot exoplanets orbiting nearby stars. It has been selected by ESA in March 2018 and adopted in November 2020 to be flown, then, in 2029. It is the first survey mission dedicated to measuring the chemical composition and thermal structures of the atmospheres of hundreds of transiting exoplanets, in order to enable planetary science far beyond the boundaries of the Solar System. The Payload (P/L) is based on a cold section (PLM – Payload Module) working at cryogenic temperatures and a warm section, located within the Spacecraft (S/C) Service Vehicle Module (SVM) and hosting five warm units operated at ambient temperature (253-313 K). The P/L and its electrical, electronic and data handling architecture has been designed and optimized to perform transit spectroscopy from space during primary and secondary planetary eclipses in order to achieve a large set of unbiased observations to shed light and fully understand the nature of exoplanets atmospheres, retrieving information about planets interior and determining the key factors affecting the formation and evolution of planetary systems

Long-Term Open-Label Vebicorvir for Chronic Hbv Infection: Safety and Off-Treatment Responses

BACKGROUND & AIMS: The investigational first-generation core inhibitor vebicorvir (VBR) demonstrated safety and antiviral activity over 24 weeks in two phase IIa studies in patients with chronic HBV infection. In this long-term extension study, patients received open-label VBR with nucleos(t)ide reverse transcriptase inhibitors (NrtIs). METHODS: Patients in this study (NCT03780543) previously received VBR + NrtI or placebo + NrtI in parent studies 201 (NCT03576066) or 202 (NCT03577171). After receiving VBR + NrtI for ≥52 weeks, stopping criteria (based on the treatment history and hepatitis B e antigen status in the parent studies) were applied, and patients either discontinued both VBR + NrtI, discontinued VBR only, or continued both VBR + NrtI. The primary efficacy endpoint was the proportion of patients with HBV DNA/ml at 24 weeks off treatment. RESULTS: Ninety-two patients entered the extension study and received VBR + NrtI. Long-term VBR + NrtI treatment led to continued suppression of HBV nucleic acids and, to a lesser extent, HBV antigens. Forty-three patients met criteria to discontinue VBR + NrtI, with no patients achieving the primary endpoint; the majority of virologic rebound occurred ≥4 weeks off treatment. Treatment was generally well tolerated, with few discontinuations due to adverse events (AEs). There were no deaths. Most AEs and laboratory abnormalities were related to elevations in alanine aminotransferase and occurred during the off-treatment or NrtI-restart phases. No drug-drug interactions between VBR + NrtI and no cases of treatment-emergent resistance among patients who adhered to treatment were observed. CONCLUSIONS: Long-term VBR + NrtI was safe and resulted in continued reductions in HBV nucleic acids following completion of the 24-week parent studies. Following treatment discontinuation, virologic relapse was observed in all patients. This first-generation core inhibitor administered with NrtI for at least 52 weeks was not sufficient for HBV cure. CLINICAL TRIAL NUMBER: NCT03780543. IMPACT AND IMPLICATIONS: Approved treatments for chronic hepatitis B virus infection (cHBV) suppress viral replication, but viral rebound is almost always observed after treatment discontinuation, highlighting an unmet need for improved therapies with finite treatment duration producing greater therapeutic responses that can be sustained off treatment. First-generation core inhibitors, such as vebicorvir, have mechanisms of action orthogonal to standard-of-care therapies that deeply suppress HBV viral replication during treatment; however, to date, durable virologic responses have not been observed after treatment discontinuation. The results reported here will help researchers with the design and interpretation of future studies investigating core inhibitors as possible components of finite treatment regimens for patients with cHBV. It is possible that next-generation core inhibitors with enhanced potency may produce deeper and more durable antiviral activity than first-generation agents, including vebicorvir

The Mid-infrared Instrument for JWST and Its In-flight Performance

The Mid-Infrared Instrument (MIRI) extends the reach of the James Webb Space Telescope (JWST) to 28.5 μm. It provides subarcsecond-resolution imaging, high sensitivity coronagraphy, and spectroscopy at resolutions of λ/Δλ ∼ 100-3500, with the high-resolution mode employing an integral field unit to provide spatial data cubes. The resulting broad suite of capabilities will enable huge advances in studies over this wavelength range. This overview describes the history of acquiring this capability for JWST. It discusses the basic attributes of the instrument optics, the detector arrays, and the cryocooler that keeps everything at approximately 7 K. It gives a short description of the data pipeline and of the instrument performance demonstrated during JWST commissioning. The bottom line is that the telescope and MIRI are both operating to the standards set by pre-launch predictions, and all of the MIRI capabilities are operating at, or even a bit better than, the level that had been expected. The paper is also designed to act as a roadmap to more detailed papers on different aspects of MIRI

The Science Performance of JWST as Characterized in Commissioning

This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies.Comment: 5th version as accepted to PASP; 31 pages, 18 figures; https://iopscience.iop.org/article/10.1088/1538-3873/acb29

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Phonon scattering by ferroelectric domain walls in potassium dihydrogen phosphate

I have studied phonon scattering by ferroelectric domain walls in KH2P04 (KDP) using thermal conductivity and phonon imaging measurements of samples in both single-domain (poled) and multidomain states. Domains were eliminated by applying a 2- 3kV /em field using evaporated electrodes. Phonon images of a poled (001) sample (at 1.7K) show two-fold symmetric focusing patterns that clearly show the small orthorhombic distortion of the lattice. Poled images are qualitatively reproduced by calculations using continuum acoustics with room temperature tetragonal elastic moduli split to orthorhombic symmetry; a rough set of low temperature orthorhombic moduli is thereby determined. The presence of domains causes a large change in ST focusing structures but little change in L and FT patterns. There is an apparent decrease in overall intensity for all modes. The images show strongly mode and polarization dependent phonon scattering. Monte Carlo simulations using acoustic mismatch (phonon reflection) to model phonon/domain wall interactions accurately reproduce the changes seen in the domained images. The low temperature (0.03-3K) thermal conductivity, K, of [100], [110], and [001] (tetragonal basis) oriented samples was measured. K in poled samples shows typical surface-limited behavior which is predicted to 13% by calculations including finite length and anisotropy and using elastic constants from the imaging simulations. Domain walls produce a 40% conductivity decrease in a [110] sample and a 30% decrease in [100) samples which is nearly independent of sample size, suggesting strong scattering of only a subset of phonons. Domain wall scattering is nearly temperature independent between 0.3K and 1K, but decreases at lower temperatures, and increases above 1K. The [001] sample couldn't be poled, but the domained K is higher than that expected from sample surface scattering. Domains parallel to the heat flow may be channeling phonons and increasing K. Acoustic mismatch calculations applied to K predict the right order of scattering, but do not reproduce the sample size effects. Orientation effects can be partially explained. The probability of diffuse scattering at the domain boundaries (often seen in Kapitza resistance studies) is at most 1%.U of I Onlydissertatio

On-orbit Thermal Performance of the JWST Mid-Infrared Instrument

Bryan Shaughnessy, Rutherford Appleton Laboratory (RAL) Space, United KingdomTim Grundy, Rutherford Appleton Laboratory (RAL) Space, United KingdomSamuel Tustain, Rutherford Appleton Laboratory (RAL) Space, United KingdomMireya Etxaluze, Rutherford Appleton Laboratory (RAL) Space, United KingdomBret Naylor, Jet Propulsion Laboratory, USAMark Weilert, Jet Propulsion Laboratory, USAICES202: Satellite, Payload, and Instrument Thermal ControlThe 52nd International Conference on Environmental Systems was held in Calgary, Canada, on 16 July 2023 through 20 July 2023.Authors Bryan M. Shaughnessy(1), Tim Grundy(1), Samuel Tustain(1), Mireya Etxaluze(1) Bret Naylor(2) and Mark Weilert(2). 1 RAL Space, STFC Rutherford Appleton Laboratory, UK 2 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA Abstract The James Webb Space Telescope (JWST) observatory was launched on the 25th December 2021. This was followed by a commissioning phase of about six months, where the observatory deployed to its final configuration and transferred to its L2 orbit location, whilst cooling science components and instruments down to their cryogenic operating temperatures. The Mid-Infrared Instrument (MIRI) is one of four scientific instruments on the JWST observatory. It provides unique capabilities to probe the deeply dust-enshrouded regions of the universe, investigating the history of star formation both near and far. The MIRI is the coldest instrument on the observatory. Its thermal design is driven by requirements to cool an Optics Module (OM) to below 16 K and detectors within this to below 7 K with a stability of <10 mK over 1000 seconds. The OM is accommodated within the passively cooled Integrated Science Instrument Module (ISIM). The instrument temperatures are achieved by a combination of thermal isolation from the ISIM and active cooling by a dedicated cryocooler. This paper summarises briefly the thermal design and pre-launch thermal verification of the instrument. It goes on to report the MIRI thermal performance through the commissioning phase, and concludes with lessons that can be applied to future similar missions