Wide-field magnetic imaging the near-field of atmospheric microplasmas using spin resonance of nitrogen-vacancy ensembles

Nitrogen-vacancy (NV) centers in diamond have been leveraged as high-precision quantum sensors for detecting magnetic and electric fields, as well as for measuring temperature and strain. Traditionally, wide-field approaches using these NV centers have been demonstrated either through cumbersome scanning methods or by using scientific-grade phase-sensitive cameras to amplify the weak NV fluorescence signal. In this work, we develop a wide-field magnetometer based on a consumer-grade astrophotography camera to image planar ensembles of NV centers in low-cost diamond nanoparticles. By embedding planar NV ensembles within ultra-thin (<50 µm) quartz wafers, we achieve optical detection of magnetic signatures within magnetohydrodynamic (MHD) flows with a sensitivity of around 500 nT/√Hz. This proximity allows for the resolution of features in microfluidic MHD and electronic systems, such as operating circuit boards or microplasma structures, while also relaxing sensitivity requirements and eliminating the effect of magnetic far-field annihilation. We apply this system to spatially-resolve the DC component of the magnetic signature of toroidal microplasmas generated purely through hydrodynamic shear.