Construction of vanes for helical pitch flow control in the Madison Dynamo Experiment

The Madison Dynamo Experiment (MDE) comprises a 1 m diameter spherical chamber that contains liquid sodium flowing under the influence of two counter rotating impellers and vanes close to the vessel wall. MDE seeks to observe a magnetic field grow at the expense of kinetic energy in the liquid sodium flow. The most recent upgrade has been the addition of three vanes symmetrically located around each impeller to control the helical pitch of the flow and thus minimize the critical velocity at which the dynamo onset occurs. Each of the new vane/shaft assemblies can be rotated anywhere in a full circle about the shaft axis and then fixed to the desired position. The design and construction of the so called rotatable vanes will be discussed and illustrated today.