Abstract: A process for preparing hyperpolarized helium gas at high pressure including optical pumping at a resonant wavelength of about 1083 nanometers a helium gas formed by pure helium-3 isotope or by a mixture of helium-3 and helium-4 isotopes; and subjecting the helium gas to a magnetic field of about 0.01 to about 1 tesla during optical pumping and maintaining pressure higher than about 10 mbar and an apparatus for preparing a hyperpolarized helium gas at high pressure including a helium gas confinement cell; an excitation laser positioned to irradiate the helium gas; and means for generating a magnetic field of about 0.01 to about 1 tesla operatively connected to the confinement cell.

Abstract: The present invention relates to an apparatus for producing polarized high-pressure vapor-phase helium-3, particularly for NMR imaging. The apparatus comprises a means for injecting helium-3 or a mixture of isotopes into an optical pumping cell (2), a means for liquefying the polarized gas from the optical pumping cell (2) and a tank (4) for storing the polarized liquid-phase helium-3, characterized in that the storage tank (4) is cooled to a temperature that may be set between a storage temperature Ta and an evaporation temperature Te, and communicates alternately with the optical pumping cell (2) and a high-pressure helium-3 gas discharge duct.