[en] Since a decade hyperpolarized ³He, used in fundamental research as well as in medical imaging, is polarized in a central facility, located at the University of Mainz and shipped to the users. The gas is polarized via metastability exchange optical pumping (MEOP) at a pressure of approximately 1 mbar inside a magnetic field of 1 mT. At these parameters the process requires the magnetic field to have a relative gradient of ΔB/B<3.8.10^-4 cm^-1. To construct a compact facility for local gas-polarization it is imperative to create a sufficiently homogeneous magnetic field all over a solenoid's volume in order to be able to use its complete volume for the MEOP assembly. Our concept of a spacious homogenization of a solenoid's magnetic field consists of enclosing it into a shielding of soft magnetic material, providing a high magnetic permeability. In addition to the homogenization of the magnetic field a new concept for the optics, used for the optical pumping has been developed, to fit into the new compact facility. Compared to the currently used facility, a neat linear motor replaces the cumbersome hydraulical drive of the piston, which compresses the gas without polarization-losses from 1 mbar up to 5 bar. The design of the compact apparatus aims to reach a flux of hyperpolarized ³He at P>65% of several standard liters per hour.

[en] The method of polarizing ³He via metastability exchange optical pumping is well known since the early 1960s. Since then hyperpolarized gases have found manifold applications in fundamental science as well as in medical research. The present polarizer apparatus in Mainz used as central facility is well established and can produce up to three standard liters of gas per hour with a polarization of 60-65 %, sufficient for medical applications. For basic research where higher degrees of polarization are needed one can reach up to 78 % at a production rate of one standard liter per hour. To provide the users with high polarization degrees and big amounts of polarized gas a compact apparatus was designed. Using this compact polarizer as local polarizing facility enables the users to avoid polarization losses during shipping. For the new polarizer several concepts had to be developed to minimize the size while retaining the production rate and polarization degree. There have been efforts in optimizing optics, polarization conserving compression of the gas and homogenization of the magnetic field. By using a closed cylinder of soft magnetic material a relative field gradient of better than ΔB/B<3.8.10^-4 cm^-1 has been obtained, which is needed to have the desired gradient relaxation time for sufficient polarization. Further results are presented in this talk.