Minimizing Pressure Inhomogeneities Across Large Samples Under Helium Pressure Media at Low Temperatures

Published

March 23, 2022

Author(s)

Juscelino Leao

Abstract

Literature shows that, when using pressure media to achieve hydrostatic pressure under a constant pressure and volume, passing thru the P x T of the pressure gas to achieve low temperatures (1.5 K ≤ T < 30 K) will cause an overall pressure reduction at base temperatures of at most 25 percent of the pressure read while under hydrostatic conditions at the P x T. In-situ inert gas high pressure vessels for neutron scattering for pressures of up to 1.0 GPa and temperatures as low as 1.5 K pose a particular problem due to the P x T phase diagram of the pressure media. A methodology for pressurization to ensure minimal pressure loss as temperature falls below the pressure media phase change, at the same time minimizing pressure inhomogeneity throughout the length of the sample; as well as calibration data are presented within this work.

Citation

Journal of Neutron Research

Volume

24

Issue

1

Pub Type

Journals

Keywords

Pressure, hydrostatic, neutron scattering, helium, pressure gradient

Citation

Leao, J. (2022), Minimizing Pressure Inhomogeneities Across Large Samples Under Helium Pressure Media at Low Temperatures, Journal of Neutron Research (Accessed May 14, 2025)