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Challenge General Fusion Challenge: Method for Sealing Anvil Under Repetitive Impacts Against Molten Metal
General Fusion Challenge: Method for Sealing Anvil Under Repetitive Impacts Against Molten Metal
STATUS: Awarded
Active Solvers: 229
Posted: Apr 15 2015
Challenge ID: 9933691
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A new method is needed to seal a metal cylinder and the metal surface of the cylindrical hole into which it fits such that molten lead on one end of the cylinder is isolated from a vacuum on the opposite end of the cylinder. The cylinder is subject to repetitive impacts and high temperatures, which must not compromise the seal. More details are provided in the body of the Challenge. 

This Challenge requires only a written proposal.


A thick-walled steel vessel has a cylindrical hole bored into it, into which a puck-shaped metal anvil fits. The vessel is filled with molten lead. Exterior to the vessel, and at the anvil, a cylindrical hammer assembly is mounted and evacuated. The hammer (similar to the anvil in size, shape and mass) is accelerated towards and impacts the anvil. The kinetic energy of the hammer is transferred through the anvil into the molten lead as a pressure wave. 

A robust seal technology is required to isolate the molten lead from the vacuum. The seal must survive high temperatures and extreme pressures over repetitive impacts. 

This is a Theoretical Challenge which requires only a written proposal to be submitted. The Challenge award will be contingent upon theoretical evaluation of the proposal by the Seeker. The solution may combine existing components, commercially available components and/or novel Solver solutions. Ideas leveraged from other industries with similar problems are encouraged.

To receive an award, the Solvers will have to transfer to the Seeker their exclusive Intellectual Property (IP) rights to the solution. 

About the Seeker

General Fusion is developing the fastest, most practical, and lowest cost path to commercial fusion energy. Established in 2002, the company and its 65 employees are supported by a global syndicate of leading energy venture capital funds, industry leaders, and technology pioneers. 

Fusion energy holds immense promise as a clean, safe and abundant energy source. Fusion generates neither pollution nor greenhouse gases and is fueled by hydrogen isotopes which are easily extracted from seawater and derived from lithium, in abundant supply. There is enough fusion fuel to power the planet for hundreds of millions of years. 

General Fusion’s Magnetized Target Fusion system uses a sphere, filled with molten lead-lithium that is pumped to form a vortex. On each fusion pulse, magnetically-confined plasma is injected into the vortex. An array of hammers, around the sphere, impact and drive a pressure wave into the center of the sphere, compressing the plasma to fusion conditions. 

For more information on General Fusion, visit

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An InnoCentive Theoretical Challenge builds upon an idea but is not yet a proof of concept. A solution to a Theoretical Challenge will solidify the Solver's concept with detailed descriptions, specifications and requirements necessary to bringing a good idea closer to becoming an actual product or service.

This Challenge is a Theoretical-IP Transfer Challenge, meaning that Solvers must relinquish all rights to the Intellectual Property (IP) for which they are awarded. By contrast, Theoretical-Licensing means that the Seeker is requesting non-exclusive rights to use the winning solution. For these forms of a Theoretical Challenge, Solvers that do not win retain the rights to their solution after the evaluation period is complete. The Seeker retains no rights to any IP not awarded.

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