At low magnetic field, the efficiency of metastability-exchange optical pumping of helium-3 is known to be optimal for pressures around 1mbar. We demonstrate on several examples (up to 32mbar) that operating in a higher magnetic field (here 0.12 T) can significantly increase the nuclear polarisations achieved at higher pressures. Since polarisation measurements cannot be made with the standard technique, we use a general optical method based on absorption measurements at 1083 nm to measure the polarisation of the atoms in the ground state.

PACS numbers: 32.80.Bx, 32.70.--n