Method and apparatus for production of spin-polarized medical-grade xenon .sup.129 gas by laser optical pumping

A method of providing spin-polarized xenon.sup.129 gas, said method comprising steps of:

• providing a reactor vessel defining a cavity
• introducing a quantity of an alkali metal into a lower portion of said cavity;
• heating said alkali metal to produce alkali metal gas;
• introducing xenon gas including a fraction of xenon.sup.129 isotope into a lower portion of said cavity;
• causing mixing and up-welling of the alkali metal gas and xenon gas within said cavity;
• providing a magnetic field traversing said cavity and said mixed and up-welling alkali metal and xenon gases;
• illuminating and optically pumping said mixed and up-welling alkali metal and xenon gases with laser light energy traversing said cavity generally perpendicularly to said up-welling gas flow to spin-polarize a significant fraction of the alkali metal gas;
• colliding molecules of said alkali metal gas with molecules of said xenon gas to transfer spin energy from said spin-polarized alkali metal gas to said xenon gas to provide a significant fraction of spin-polarized xenon.sup.129 gas;
• flowing the mixed alkali metal and xenon gases including said spin-polarized xenon.sup.129 gas together from said reactor vessel;
• and
• cryogenically condensing said alkali metal gas and separating the xenon gas from the condensed alkali metal to provide a flow of xenon gas including said spin-polarized xenon.sup.129 gas.

An apparatus for providing medical-grade spin-polarized xenon.sup.129 gas, particularly for use as a contrast medium for human inhalation during magnetic resonance imaging procedures, said apparatus comprising:

• a reactor vessel, said reactor vessel defining a cavity for receiving an alkali metal and xenon gas including a fraction of xenon.sup.129 isotope, said reactor vessel including a heater disposed at a floor of said reactor vessel for gasifying said alkali metal, gas inflow and outflow means for receiving and discharging the xenon gas into and from said cavity, said gas inflow and outflow means providing for mixing of said alkali metal gas with said xenon gas to up-well the mixed gases in said cavity;
• magnetic means providing a magnetic field traversing said cavity and said mixed flow of alkali metal and xenon gases up-welling in said cavity;
• laser means for projecting laser light energy across said cavity generally horizontally to illuminate said up-welling mixed alkali metal and xenon gases to optically pumping these gases spin-polarize a significant fraction of the alkali metal gas, said spin-polarized alkali metal gas transferring spin energy to the xenon gas by molecular collision between alkali metal gas molecules and xenon gas molecules in the mixed and up-welling gases to provide a significant fraction of spin-polarized xenon gas including spin-polarized xenon.sup.129 gas;
• cryogenic alkali metal gas condensation and separation means including a gas flow means for receiving the mixed alkali metal and xenon gases, for chilling these mixed gases to a temperature of at least -60 degrees Centigrade or lower and condensing said alkali metal gas to a solid form, and for allowing continued flow to an exit of xenon gas including said spin-polarized xenon.sup.129 gas;
• said laser means including a diode laser light bar providing a plane of laser light energy traversing said cavity and through which substantially all of said mixed alkali metal and xenon gas flow up-welling in said cavity must flow to be optically pumped.