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Electrode Surface Erosion at High Pressures


TECHNOLOGY AREAS: Materials/Processes

OBJECTIVE:  Develop a computational model to predict the flow field in the attachment region of an electric arc and the associated material removal.

DESCRIPTION:  Data and the ability to predict surface heating and material removal of electrodes at moderate to high pressures (10-300 atm) with a moving arc is needed. The complexity of the process of electrode erosion, involving extreme temperatures (~14,000 K), a complex charge concentration zone, a material/gas interface, and the creation of a liquid pool at the arc foot, combined with the difficulty in obtaining validation data due to the brightness, temperatures, and voltages involved has limited the capability to model electrode material removal.  Current models can predict material removal rates within about an order of magnitude but there are many factors that are poorly understood such that many different parameter settings can generate the same results.  The flow field in the region of the arc attachment region; the constriction and attachment of the arc; the magnetic field produced by the arc; the effect on the arc of externally applied magnetic fields; the melting and vaporization of the electrode surface; removal of material due to surface shear, chemical processes, magnetic forces, and material vaporization; and the flow of current once within the electrode surface all must be understood and relevant models included in the computational model.

PHASE I:  Develop the theory needed to model the relevant processes & identify existing computational tools that can be utilized as is or in a modified form in development of the final computational tool.  Develop the architecture for the computation tool & a design for the test apparatus to be used to gather data needed to develop & tune the model.

PHASE II:  Develop the computational model.  Construct experimental apparatus and perform tests and analysis needed to determine properties, understand relevant processes, and develop databases for use by the computational tool.  Tune computational model and validate using experimental data.


Military Application:  Computational tool has military uses in the design of electrodes for arc heaters and rail guns.

Commercial Application:  Computational tool could be used to aid in the design of large transformers and other electrical equipment.

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