Fig. 4. Sample extraction and hyperpolarization sheltering method.

¹³C polarization losses as a function of the sample vertical position inside the polarizer while using a traditional DNP probe. The experiment was repeated for a non-thermalized sample (blue circles) and a thermalized sample (black circles) (A). ¹³C polarization losses as a function of the sample vertical position inside the polarizer while using the DNP probe equipped with permanent magnets. The experiment was performed for a thermalized sample only (red circles). The gray shaded area represents the area covered by permanent magnets in the probe. The last point was measured after lifting the sample up to the loading chamber and closing the mini-gate valve for 10 s (B). Calculated magnetic field value as a function of the distance from the polarizer isocenter. The magnetic field generated by the polarizer coil is parallel to the probe axis (red dotted line), while the magnetic field generated by the permanent magnets is perpendicular to the probe axis (blue dotted line). The norm of the total field is also reported (green continuous line) (C).