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Abstract Given the important role turbulence plays in the settling and growth of dust grains in protoplanetary disks, it is crucial that we determine whether these disks are turbulent and to what extent. Protoplanetary disks are weakly ionized near the midplane, which has led to a paradigm in which largely laminar magnetic field structures prevail deeper in the disk, with angular momentum being transported via magnetically launched winds. Yet, there has been little exploration of the precise behavior of the gas within the bulk of the disk. We carry out 3D, local shearing box simulations that include all three low-ionization effects (ohmic diffusion, ambipolar diffusion, and the Hall effect) to probe the nature of magnetically driven gas dynamics 1–30 au from the central star. We find that gas turbulence can persist with a generous yet physically motivated ionization prescription (order unity Elsässer numbers). The gas velocity fluctuations range from 0.03 to 0.09 of the sound speedc_sat the disk midplane to ∼c_snear the disk surface, and are dependent on the initial magnetic field strength. However, the turbulent velocities do not appear to be strongly dependent on the field polarity, and thus appear to be insensitive to the Hall effect. The midplane turbulence has the potential to drive dust grains to collision velocities exceeding their fragmentation limit, and likely reduces the efficacy of particle clumping in the midplane, though it remains to be seen if this level of turbulence persists in disks with lower ionization levels. 

Abstract Magnetic fields in the early solar system may have driven the inward accretion of the protoplanetary disk (PPD) and generated instabilities that led to the formation of planets and ring and gap structures. The Allende carbonaceous chondrite meteorite records a strong early solar system magnetic field that has been interpreted to have a PPD, dynamo, or impact‐generated origin. Using high‐resolution magnetic field imaging to isolate the magnetization of individual grain assemblages, we find that only Fe‐sulfides carry a coherent magnetization. Combined with rock magnetic analyses, we conclude that Allende carries a magnetization acquired during parent body chemical alteration at ~3.0–4.2 My after calcium aluminum‐rich inclusions in an >40 µT magnetic field. This early age strongly favors a magnetic field of nebular origin instead of dynamo or solar wind alternatives. When compared to other paleomagnetic data from meteorites, this strong intensity supports a central role for magnetic instabilities in disk accretion and the presence of temporal variations or spatial heterogeneities in the disk, such as ring and gap structures.