High Field Diamond Magnetometry Towards Tokamak Diagnostics

Nitrogen vacancy centres (NVC) in diamond have been widely used for near-dc magnetometry. The intrinsic properties of diamonds make them potential candidates for tokamak fusion power diagnostics, where radiation-hard magnetometers will be essential for efficient control. An NVC magnetometer placed in a tokamak will need to operate within a $\ge$ 1 T magnetic field. In this work, we demonstrate fibre-coupled ensemble NVC optically detected magnetic resonance (ODMR) and magnetometry measurements at magnetic fields up to 1.2 T. Sensitivities of approximately 240 to 600 nT/$\sqrt{\text{Hz}}$ and 110 nT/$\sqrt{\text{Hz}}$ are achieved in a (10-150) Hz frequency range, for non-degenerate and near-$⟨$111$⟩$ field alignments respectively.