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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,009 records · Page 56
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Design and On-Orbit Operation of the Adiabatic Demagnetization Refrigerator on the Hitomi Soft X-Ray Spectrometer Instrument

The Soft X-ray Spectrometer instrument on the Astro-H observatory contains a 6x6 array of x-ray microcalorimeters that is cooled to 50 mK by an adiabatic demagnetization refrigerator (ADR). The ADR consists of three stages in order to provide stable detector cooling using either a 1.2 K superfluid helium bath or a 4.5 K Joule-Thomson (JT) cryocooler as its heat sink. When liquid helium is present, two of the ADR's stages are used to single-shot cool the detectors while rejecting heat to the helium. After the helium is depleted, all three stages are used to continuously cool the helium tank (to about 1.5 K) and single-shot cool the detectors (to 50 mK), using the JT cryocooler as its heat sink. The Astro-H observatory, renamed Hitomi after its successful launch in February 2016, carried approximately 36 liters of helium into orbit. On day 5, the helium had cooled sufficiently (<1.4 K) to allow operation of the ADR. This paper describes the design, operation and on-orbit performance of the ADR, and the use of the ADR's heat rejection as a tool for mass gauging the helium tank.

adiabatic demagnetization refrigerator↗
NASA NTRS2018

ADR Design and Operation for the X-Ray Imaging and Spectrometer Mission (XRISM)

Following the loss of the Hitomi x-ray astronomy satellite 38 days after its launch in early 2016, the US and Japanese space agencies (NASA and JAXA) agreed to fund a replacement mission, presently called XARM. XARM will include only the two soft x-ray instruments from Hitomi, the Soft X-ray Spectrometer (SXS), and the Soft X-ray Imager (SXI). For XARM, the spectrometer instrument named Resolve will be rebuilt to the original SXS design. It consists of a 6x6 array of silicon microcalorimeters cooled to 50 millikelvin by means of a 3-stage adiabatic demagnetization refrigerator (ADR) whose operation is supported by a 40 liter superfluid helium tank, a 4.5 K Joule-Thomson cryocooler and a number of 2-stage Stirling cryocoolers. These components were all successfully demonstrated on Hitomi before its failure. This talk will summarize the design of the XARM ADR and how it differs from the SXS version, and will briefly summarize on-orbit ADR performance during Hitomi's operational period.

adiabatic demagnetization refrigeration↗
NASA NTRS2019

3-Stage ADR for the X-Ray Imaging and Spectrometer Mission (XRISM)

Following the loss of the Hitomi x-ray astronomy satellite shortly after its launch in early 2016, the US and Japanese space agencies (NASA and JAXA) agreed to fund a replacement mission, presently called the X-Ray Imaging and Spectroscopy Mission (XRISM). XRISM will include only the two soft x-ray instruments from Hitomi, the Soft X-ray Spectrometer (SXS), and the Soft X-ray Imager (SXI). The spectrometer instrument, now named Resolve, will be similar to the original SXS design. It consists of a 6 by 6 array of silicon microcalorimeters cooled to 50 millikelvin by means of a 3-stage Adiabatic Demagnetization Refrigerator (ADR) whose operation is supported by a 40 liter superfluid helium tank, a 4.5-degrees-Kelvin Joule-Thomson cryocooler and a number of 2-stage Stirling cryocoolers. These components were all successfully demonstrated on Hitomi before its failure. This talk will summarize the design of the XRISM ADR and how it differs from the SXS version.

ADR (Adiabatic Demagnetization Refrigerator)↗
DOE OSTI2017

Axial deformed solution of the Skyrme-Hartree-Fock-Bogolyubov equations using the transformed harmonic oscillator Basis

HFBTHO is a physics computer code that is used to model the structure of the nucleus. It is an implementation of the nuclear energy Density Functional Theory (DFT), where the energy of the nucleus is obtained by integration over space of some phenomenological energy density, which is itself a functional of the neutron and proton densities. In HFBTHO, the energy density derives either from the zero-range Dkyrme or the finite-range Gogny effective two-body interaction between nucleons. Nuclear superfluidity is treated at the Hartree-Fock-Bogoliubov (HFB) approximation, and axial-symmetry of the nuclear shape is assumed. This version is the 3rd release of the program; the two previous versions were published in Computer Physics Communications [1,2]. The previous version was released at LLNL under GPL 3 Open Source License and was given release code LLNL-CODE-573953.

Perez, R. Navarro↗
DOE OSTI2015

Measurements of Thermal Impedance on Superconducting Radiofrequency Cavities

The thermal impedance of niobium plays an important role in the stability of the superconducting radio frequency cavities used in particle accelerators. During the operation of SRF cavities, the RF power dissipated on the inner surface of the cavities and the heat transport to the helium bath depend on the thermal conductivity of niobium and the Kapitza conductance of the interface between the niobium and superfluid helium. Here, we present the results of measurements done on samples as well as on SRF cavities made of both ingot and fine-grain Nb to explore the effect of the surface preparation and crystal structure on the thermal impedance.

Dhakal, Pashupati↗
DOE OSTI2022

Simulating long-range coherence of atoms and photons in quantum computers

Lasers and Bose-Einstein condensates (BECs) exhibit macroscopic quantum coherence in seemingly unrelated ways. Lasers possess a well-defined global phase and are characterized by large fluctuations in the number of photons. In BECs of atoms, instead, the number of particles is conserved and the global phase is undefined. Here, we present a unified framework to simulate lasers and BECs states in gate-based quantum computers, by mapping bosonic particles to qubit excitations. Our approach relies on a scalable circuit that measures the total number of particles without destroying long-range coherence. We introduce complementary probes to measure the global and relative phase coherence of a quantum state, and demonstrate their functionality on a Rigetti quantum computer. Our work shows that particle-number conservation enhances long-range phase coherence, highlighting a mechanism used by superfluids and superconductors to gain phase stiffness.

Torre, Emanuele Dalla↗
DOE OSTI2022

Quasiparticle spectroscopy, transport, and magnetic properties of Nb films used in superconducting transmon qubits

Niobium thin films on silicon substrate used in the fabrication of superconducting qubits have been characterized using scanning and transmission electron microscopy, electrical transport, magnetization, quasiparticle spectroscopy, and real-space real-time magneto-optical imaging. We study niobium films to provide an example of a comprehensive analytical set that may benefit superconducting circuits such as those used in quantum computers. The films show outstanding superconducting transition temperature of $T_{c}=9.35$ K and a fairly clean superconducting gap, along with superfluid density enhanced at intermediate temperatures. These observations are consistent with the recent theory of anisotropic strong-coupling superconductivity in Nb. However, the response to the magnetic field is complicated, exhibiting significantly irreversible behavior and insufficient heat conductance leading to thermo-magnetic instabilities. These may present an issue for further improvement of transmon quantum coherence. Possible mitigation strategies are discussed.

Joshi, Kamal R.↗
DOE OSTI2023

Cryogenic testing of the first HL-LHC Q1/Q3 cryo-assembly at Fermilab

In early 2023, Fermilab is conducting horizontal cryogenic testing of the first Q1/Q3 cryo-assembly for the high-luminosity LHC upgrade (HL-LHC). The cryo-assembly was installed on the upgraded Fermilab horizontal test stand previously used for testing the LHC inner triplet quadrupoles. The cryogenic process requirements of this test include controlled cool-down and warm-up with a 100 K maximum temperature differential between the two ends of the cold mass, operation of a 1.3 bar, 1.9 K bath of subcooled superfluid helium during power testing and magnetic measurements, and operation at pressure up to 18 bar with full helium recovery after a quench. This paper presents the operational experience gained from this first test.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Cryogenic testing of HL-LHC Q1/Q3 cryo-assemblies at Fermilab

Fermilab is conducting horizontal cryogenic testing of Q1/Q3 cryo-assemblies for the high-luminosity LHC upgrade (HL-LHC). Cryo-assemblies are installed on the upgraded Fermilab horizontal test stand previously used for testing the LHC inner triplet quadrupoles. The cryogenic process requirements of these tests include controlled cool-down and warm-up with a 100 K maximum temperature differential between the two ends of the cold mass, operation of a 1.3 bar, 1.9 K bath of subcooled superfluid helium during power testing and magnetic measurements, and operation at pressure up to 18 bar with full helium recovery after a quench. This paper presents the operational experience gained from the first tests as well as improvement for subsequent tests.

Rabehl, R. [Fermilab] (ORCID:0000000311130030)↗
DOE OSTI2025

Fabrication of the HFVMTF Double-Bath Cryostat

The High Field Vertical Magnet Test Facility (HFVMTF) at Fermilab is designed to test superconducting magnets up to 20 tons and 1.3 meters in diameter. Central to the facility is a double-bath superfluid helium cryostat reaching 1.8 K at 1.2 bar. Integrated with a 15 T superconducting dipole from LBNL, HFVMTF supports HTS cable testing for fusion applications. This paper presents the design and fabrication of the cryostat, with a focus on two complex components: the 2 K heat exchanger and the lambda plate. The heat exchanger thermally links sub-atmospheric and pressurized helium baths. The 1.4-meter lambda plate provides thermal isolation and structural support for over 20 tons under 1.3 bar pressure differential. Finite Element Analysis validated the vessel's integrity under maximum load conditions.

Bruce, R. [Fermilab] (ORCID:0000000234200612)↗
DOE OSTI2026

Neural-network quantum states for the nuclear many-body problem

A long-standing goal of nuclear theory is to explain how the structure and dynamics of atomic nuclei and neutron-star matter emerge from the underlying interactions among protons and neutrons. Achieving this goal requires solving the nuclear quantum many-body problem with high accuracy across a wide range of length scales and density regimes. In this review, we discuss how artificial neural network representations of the nuclear many-body wave function have significantly extended the capabilities of continuum quantum Monte Carlo methods. In particular, neural network quantum states enable calculations of larger systems than were previously accessible and provide a flexible framework for capturing phenomena that challenge conventional approaches, including the emergence of nuclear clusters and superfluid phases in dense matter. We highlight recent applications to finite nuclei, infinite nuclear and neutron matter, and dynamical processes relevant to lepton-nucleus and nucleus-nucleus scattering. We also discuss conceptual and methodological connections with condensed matter physics, emphasizing developments in neural network quantum states that bridge strongly correlated systems across disciplines. Together, these developments demonstrate how neural-network methods open new avenues toward unified and accurate descriptions of nuclear structure, matter, and reactions.

Lovato, Alessandro [Argonne; TIFPA-INFN, Trento; V↗
DOE OSTI2022

Thermodynamic properties of nodal superconductors close to a magnetic quantum critical point

In this work we study thermodynamic manifestations of the quantum criticality in multiband unconventional superconductors. As a guiding example we consider the scenario of magnetic quantum critical point in the model that captures superconductivity coexistence with the spin-density wave. We show that in situations when the superconducting order parameter has incidental nodes at isolated points, quantum magnetic fluctuations lead to the renormalization of the relative 𝑇-linear slope of the London penetration depth. This leads to the nonmonotonic dependence of the penetration depth as a function of doping and the concomitant peak structure across the quantum critical point. In addition, we determine contribution of magnetic fluctuations to the specific heat at the onset of the coexistence phase. Furthermore, our theoretical analysis is corroborated by making a comparison of our results with the recent experimental data from the low-temperature thermodynamic measurements at optimal composition in BaFe 2 (As 1-x P x ) 2 .

36 MATERIALS SCIENCE↗
DOE OSTI2016

Coupled motion of Xe clusters and quantum vortices in He nanodroplets

Single He nanodroplets doped with Xe atoms are studied via ultrafast coherent x-ray diffraction imaging. The diffraction images show that rotating He nanodroplets about 200 nm in diameter contain a small number of symmetrically arranged quantum vortices decorated with Xe clusters. Furthermore, unexpected large distances of the vortices from the droplet center (≈0.7-0.8 droplet radii) are explained by a significant contribution of the Xe dopants to the total angular momentum of the droplets and a stabilization of widely spaced vortex configurations by the trapped Xe clusters.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2026

Uranium Doped Gallium Nitride Epitaxial Thin Films

Gallium nitride (GaN) is near ubiquitous in modern day technologies, forming the backbone of solid-state lighting and high-power electronics. Engineering the physical properties of GaN has been investigated to some degree by the incorporation or doping of most of the elements of the periodic table, but the actinides remain unexplored. Molecular beam epitaxy is used to demonstrate uranium doping of GaN single crystals. High structural quality of the host matrix is maintained despite partial elemental segregation of the uranium dopant into 1D structures at the levels presented here. Electronic transport measurements reveal relatively high conductivity, which persists down to cryogenic temperature and is characterized by the formation of narrow gaps in the electronic band structures very close to the Fermi level. Photoluminescence measurements reveal that the U-doped GaN exhibits optical behavior similar to that of the GaN substrate. The addition of actinide materials to a non-centrosymmetric, optically active, radiation-hard, and electronically tunable host matrix opens a world of possibilities for investigating and leveraging elements with high electron correlations in the pursuit of novel devices.

36 - MATERIALS SCIENCE↗
DOE OSTI2017

Response Functions for the Two-Dimensional Ultracold Fermi Gas: Dynamical BCS Theory and Beyond

Response functions are central objects in physics. They provide crucial information about the behavior of physical systems, and they can be directly compared with scattering experiments involving particles such as neutrons or photons. Calculations of such functions starting from the many-body Hamiltonian of a physical system are challenging and extremely valuable. In this paper, we focus on the two-dimensional (2D) ultracold Fermi atomic gas which has been realized experimentally. We present an application of the dynamical BCS theory to obtain response functions for different regimes of interaction strengths in the 2D gas with zero-range attractive interaction. We also discuss auxiliary-field quantum Monte Carlo (AFQMC) methods for the calculation of imaginary time correlations in these dilute Fermi gas systems. Illustrative results are given and comparisons are made between AFQMC and dynamical BCS theory results to assess the accuracy of the latter.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Integrated SQUID/Sensor Metallic Magnetic Microcalorimeter for Gamma-Ray Spectroscopy

Metallic magnetic microcalorimeters (MMCs) achieve energy resolution comparable to transition-edge sensors (TESs) but rely on different measurement physics that may allow MMCs to surpass TESs in some future applications. We have recently completed fabrication of new MMC γ-ray detector arrays using several exploratory sensor designs. All designs integrate the SQUID and sensor on the same chip and use a superconducting cap layer on the paramagnet, but explore different combinations of combined/separate sensing and magnetization coils and direct/flux transformer coupling to the input SQUIDs. This report describes the design and initial testing of one of these devices, which has so far demonstrated an energy resolution of 38 eV at 60 keV near 10 mK using natural-abundance silver–erbium paramagnet.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Equilibrium Properties of the Mixed State in Superconducting Niobium in a Transverse Magnetic Field: Experiment and Theoretical Model

Equilibrium magnetic properties of the mixed state in type II superconductors were studied on high-purity film and single-crystal niobium samples with different Ginzburg-Landau parameters in perpendicular and parallel magnetic fields using dc magnetometry and scanning Hall-probe microscopy. The magnetization curve for samples with unity demagnetizing factor (slabs in perpendicular field) was obtained for the first time. It was found that none of the existing theories is consistent with these new data. To address this problem, a theoretical model is developed and comprehensively validated. The new model describes the mixed state in an averaged limit, i.e., without detailing the samples’ magnetic structure and therefore ignoring the surface current and interactions between the structural units (vortices). At low values of the Ginzburg-Landau parameter, it converts to the model of Peierls and London for the intermediate state in type I superconductors. The model quantitatively describes the magnetization curve for the perpendicular field and provides new insights into the properties of the mixed state, including properties of individual vortices. In particular, it suggests that description of the vortex matter in superconductors of the transverse geometry as a “gas-like” system of non-interacting vortices is more appropriate than the frequently used solid-like scenarios.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗