Melora Larson

Jet Propulsion Laboratory

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Document Type

Co-Authors

Ulf Israelsson

Jet Propulsion Laboratory

N. Mulders

University of Delaware

Al Nash

Jet Propulsion Laboratory

Talso Chui

Jet Propulsion Laboratory

John Panek

Goddard Space Flight Center

John Pensinger

Jet Propulsion Laboratory

Masoud Mohazzab

University of Delaware

Feng-Chuan Liu

Chang Gung University

Mark J. Lysek

Jet Propulsion Laboratory

Guenter Ahlers

University of California, Santa Barbara

Cooperative Institutions

Space Telescope Science Institute

455

Goddard Space Flight Center

282

Northrop Grumman (United States)

124

Jet Propulsion Laboratory

California Institute of Technology

Johns Hopkins University

Michigan Science Center

University of Arizona

European Space Research and Technology Centre

European Space Agency

Author Statistics

Papers

Citation

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Research Field

Measurements of Tx(Q,P): Depression of the Superfluid Transition Temperature by a Heat Current Along the Lambda Line

Yuanming Liu Melora Larson Ulf Israelsson

We report experimental measurements of Tc (Q,P) for heat currents (Q) between I1and 100 micro W/sq cm and pressure (P) between SVP and 15 bar. The measurements were performed in a normal gravity environment, using the low-gravity simulator facility at JPL without the magnet being energized. The sample pressure was controlled to 0.1 micro bar using a hot volume, and a Straty-Adams capacitive pressure gauge. The total volume of helium in the sample cell and the hot volume was held constant using a pneumatic low temperature valve. A melting curve thermometer (MCT) measured the transition temperature (Tc) with a resolution of about 10 nK through a sidewall probe of the thermal conductivity sample cell. We employed the same measurement technique and procedure described by DAS. Preliminary results indicate that Tc (Q,P) depends very little on the pressure in the pressure range between SVP and 15 bar with a variation in the amplitude of Tc(Q,P) of less than about 5% observable in this pressure range. According to the Renormalization-group theory calculation by Haussmann and Dohm, the amplitude of Tc (Q,P) has a leading pressure-dependence term proportional to xi(sub 0) (sup (1/nu)), where xi(sub 0) is the correlation-length amplitude and nu is the correlation-length exponent. Thus, a small pressure dependence of the amplitude of Tc (Q,P) is expected since xi(sub 0) is very weakly dependent on pressure between SVP and 15 bar, consistent with our measurements.

Bar (unit)

Atmospheric temperature range

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Update on the low temperature microgravity physics facility

D. Langford John Pensinger G.J. Dick Melora Larson

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The Legacy of the Low Temperature Microgravity Physics Facility

Melora Larson John Pensinger Feng-Chuan Liu Donald Langford Inseob Hahn

The Jet Propulsion Laboratory (JPL) has been building the Low Temperature Microgravity Physics Facility (LTMPF) as a multi-user research facility for the International Space Station. Because of the recent Presidential Exploration Initiative placed on NASA, NASA has informally told JPL to phase out the development of the LTMPF, assuming a suspension of funding at the end of fiscal year 2004. Over the last five years of development of the Facility, a tremendous legacy of both scientific and technical progress has been made, and a significant amount of flight hardware has been built. During these last few months of remaining funding, the LTMPF plans on finishing some remaining development efforts, archiving the hardware (flight and engineering models), software, and capturing the knowledge generated for possible future missions. These possible future missions could include gravitational or relativistic physics experiments (around the Earth or the Moon), charged particle physics experiments away from the Earth, possible other fundamental physics experiments in a Code U-developed free flyer orbiting the Earth, or even gravitational mapping experiments around the Moon or possibly Mars. LTMPF-developed technologies that are likely to have substantial impact on such future missions include SQUID magnetometers and thermometers, ultra-high-performance cryogenics, and high-Q superconducting resonators.

Space physics

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Citations (0)

Journal of Low Temperature Physics (1998)

Haiying Fu H. Baddar Kerry Kuehn Melora Larson N. Mulders

Thermometer

10.1023/a:1022246124415

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Citations (18)

Superconducting transition thermometry for 4He lambda point experiments

Physica B Condensed Matter (1990)

Melora Larson Guenter Ahlers

Thermometer

Transition temperature

10.1016/s0921-4526(90)80868-j

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Citations (4)

Thermal expansion coefficient near the superfluid transition ofHe4in an aerogel

Physical Review Letters (1992)

Melora Larson N. Mulders Guenter Ahlers

We measured the isobaric thermal expansion coefficient ${\mathrm{\ensuremath{\beta}}}_{\mathit{P}}$ near the superfluid transition of $^{4}\mathrm{He}$ in an aerogel along six isobars between 3 and 24 bars. The data yield the specific-heat exponents \ensuremath{\alpha} and \ensuremath{\alpha}' and amplitude ratio A/A'. Fits by power laws in t\ensuremath{\equiv}T/${\mathit{T}}_{\mathit{c}}$-1, where ${\mathit{T}}_{\mathit{c}}$ is the transition temperature, produced \ensuremath{\alpha}\ensuremath{\simeq}-0.6 and \ensuremath{\alpha}'\ensuremath{\simeq}-1.0\ensuremath{\ne}\ensuremath{\alpha}. Including an analytic background a\ifmmode\times\else\texttimes\fi{}t permitted \ensuremath{\alpha}=\ensuremath{\alpha}'\ensuremath{\simeq}-0.59, but required a very large coefficient a and yielded A'/A\ensuremath{\simeq}0. The exponents are inconsistent with that of ${\mathrm{\ensuremath{\rho}}}_{\mathit{s}}$ and hyperscaling in three dimensions.

Exponent

Transition temperature

10.1103/physrevlett.68.3896

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Citations (38)

The James Webb Space Telescope Mission

arXiv (Cornell University) (2023)

Jonathan P. Gardner John C. Mather R. Abbott James S. Abell Mark Abernathy

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.

Spitzer Space Telescope

Aperture (computer memory)

10.48550/arxiv.2304.04869

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Citations (12)

SIRTF telescope test facility

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (1996)

Daniel R. Coulter Steven A. Macenka Mark J. Lysek Melora Larson

In this paper we describe the key features of the SIRTF Telescope Test Facility developed at the Jet Propulsion Laboratory. Information on the cryogenic performance including details of the test cycle time and cryogen hold time are included. Emphasis is on the operation of the facility. Data are presented on the cryogenic optical testing of the ultra-lightweight 85 cm diameter beryllium primary mirror assembly for the infrared telescope technology testbed.

Infrared telescope

Jet propulsion

Testbed

10.1117/12.243517

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Citations (1)

Journal of Low Temperature Physics (1998)

Masoud Mohazzab N. Mulders Melora Larson Al Nash

Tricritical point

Exponent

10.1023/a:1022508501937

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