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HH 211 is a highly collimated jet with a chain of knots and a wigglestructure on both sides of a young Class 0 protostar. We used two epochs ofAtacama Large Millimeter/submillimeter Array (ALMA) data to study its inner jetin the CO(J=3-2), SiO(J=8-7), and SO(N_J=8_9-7_8) lines at $\sim$25 AUresolution. With these ALMA and previous 2008 Submillimeter Array (SMA) data,the proper motion of 8 knots within $\sim$250 AU of the central source is foundto be $\sim$0.068" per year ($\sim$102 km/s), consistent with previousmeasurements in the outer jet. At $\sim$4 times higher resolution, thereflection-symmetric wiggle can be still fitted by a previously proposedorbiting jet source model. Previously detected continuous structures in theinner jet are now resolved, containing at least 5 sub-knots. These sub-knotsare interpreted in terms of a variation in the ejection velocity of the jetwith a period of $\sim$4.5 years, shorter than that of the outer knots. Inaddition, backward and forward shocks are resolved in a fully-formed knot, BK3,and signatures of internal working surface and sideways ejection are identifiedin Position-Velocity diagrams. In this knot, low-density SO and CO layers aresurrounded by a high-density SiO layer.

25 AU Angular Resolution Observations of HH 211 with ALMA : Jet Properties and Shock Structures in SiO, CO, and SO