Three Meter Experiment
The 3 meter dynamo project is under construction. When complete, the 3 meter diameter sphere will contain over 13,000 kg of sodium. Originally, this system was intended to be driven by a pair of propellers, like Dynamo II. We have decided instead to build a spherical couette system with a radius ratio of 1/3, like that used in the magnetorotational instability experiments (which was Dynamo II with a sphere instead of propellers). Like Dynamo III, the whole vessel will be capable of rotation. This system will be capable of generating a flow with magnetic Reynolds number of nearly 700.

The move to a spherical couette geometry will make this experiment more useful for benchmarking numerical MHD codes. The complicated forcing of counterrotating propellers were a hindrance to numerics. A spherical geometry is more natural, and will likely make the analysis of our results simpler.







The sphere is nearing completion. Below are some photos of the sphere and the highbay where the experiment will be located.

View of the highbay showing the lower frame, reinforced concrete motor pedestal with two (out of position) motors, and the plate on which the sphere base will rest.	The outer sphere is receiving finishing touches at Central Fabricators in Cincinatti. It will arrive in late September or early October, 2004. Photo courtesy of Dan Meade, Central Fabricators	The speed of each 250kW (350HP!) induction motor will be controlled by one of these variable frequency drives.
Two 4m I.D magnets have been constructed to apply fields up to about 0.02T to the system to study induced field dynamics. (The bottom magnet is white, the top orange) The variable frequency drives are also shown in this picture.

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Questions or comments? Contact Dan Lathrop, Dan Z., or Santiago
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