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Israelsson, U. E.

Publications and source records attributed to Israelsson, U. E..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1996

Opportunities for Low Temperature Research Aboard the Space Station

A cryogenic Space Station facility is being developed by the Jet Propulsion Laboratory and industrial partners to support the microgravity needs of the international scientific community....Capabilities, conceptual designs and development plans for the facility will be discussed along with a summary of potential near term flight candidate experiments.

Space Station cryogenic microgravity↗
NASA NTRS1995

(abstract) Wide Dynamic Range Porous Plug and Vent Line for SIRTF

The most recent approach to the Space Infrared Telescope Facility (SIRTF) uses a new design concept in which the telescope is launched warm and subsequently cooled to operating temperture on orbit. At launch the cryostat is at 2 K and the telescope is at room temperature. Cooldown of the telescope will be accomplished initially through radiation to space. Final cooldown to the 5.5 K operating temperature is done with helium vapor. Initially the helium flow on orbit will be 10 to 20 times larger than required for steady-state operation. The vent line and the liquid-vapor phase separator (porous plug) therefore must accomodate a large dynamic operational range. For ground testing of IR instruments, the required temperature is 1.5 K. The helium tank temperature for both ground testing and space operations thus needs to be 1.4 K. We will present a discussion of the requirements, a conceptual design, and initial laboratory test results with candidate porous plugs and associated instrumentation. A discussion of possible connections to the design of Gravity Probe-B cryostat will also be presented.

infrared space helium cryostat↗
NASA NTRS1995

The Superfluid Transition of Helium-4 in the Presence of an Applied Heat Flow in 1-g and Below: Comparison between Experiment and Numerical Simulations

Reported are thermal conductivity measurements of liquid Helium-4 at saturated vapor pressure. measurements were made inside a super- conducting magnet. The thermal conductivity measurements consist of ramping the temperature at the cell top while passing a constant heat current through the cell from the bottom. Numerical results are quantitatively compared with the observed experimental behavior.

superfluid helium-4 numerical simulations thermal ↗
NASA NTRS1993

Dynamic Measurements Near the Lambda-point in a Low-G Simulator on the Ground

The properties of liquid helium very near the lambda-transition in the presence of a heat current has received recent theoretical and experimental attention. In this regime, gravity induced pressure effects place severe constraints on the types of experiments that can be performed. A new experiment is described which largely overcomes these difficulties by magnetostrictively canceling gravity influences in the helium sample with a suitable magnetic coil. Design limitations of the technique and a discussion of proposed experiments is presented.

Israelsson, U. E.↗
NASA NTRS1993

Dynamic Measurements Near the Lambda-point in a Low-gravity Simulator on the Ground

The properties of liquid helium very near the lambda-transition in the presence of a heat current has received recent theoretical and experimental attention. In this regime, gravity induced pressure effects place severe constraints on the types of experiments that can be performed. A new experiment is described which largely overcomes these difficulties by magnetostrictively canceling gravity influences in the helium sample with a suitable magnetic coil. Design limitations of the technique and a discussion of proposed experiments is presented.

Israelsson, U. E.↗
NASA NTRS1993

Design of a Low Gravity Simulator for Performing Non-Equilibrium Investigations near the Lambda Transition of ^4He

A design is presented of a low gravity simulator where a magnetic field gradient is employed to oppose the hydrostatic pressure effects of gravity. It appears feasible to reduce the effective gravity environment of the helium in the cell by about two orders of magnitude. The corresponding shift in transition temperature with vertical height would be reduced to 12.7 nK/cm. Methods for instrumenting the simulator to perform high resolution investigations of non-equilibrium phenomena near the lambda point are presented. The advantages of using a low gravity simulator in searching for the predicted change in character of the superfluid transition from continuous to first order in the presence of a heat current are also discussed.

Israelsson, U. E.↗