Massachusetts Institute of Technology

Dennis G Whyte

Zachary S Hartwig

Brandon N Sorbom

Sara Ferry

Caroline Sorensen

Jeffrey Freidberg

Ethan Peterson

A 'liquid sandwich' vacuum vessel for magnetic confinement fusion of plasma includes two rigid structural “bread” members that form a double-walled vessel and a non-structural “cheese” material disposed between the walls. The inner member is semi-conductive and encloses a volume of fusing plasma, while the outer member may contact a neutron shield (e.g. a molten salt blanket) and is corrosion-resistant. The non-structural material is solid at room temperature, but is molten during fusion, and is preferably lead. The structural members may be steel or silicon carbide, or similar structural material. During a disruption of fusion, excess electrical energy that escapes from the plasma into the vessel will primarily shear the liquid material rather than the structural members, allowing the “bread” to be thin.

Liquid sandwich vacuum vessel for magnetic fusion

Disclosed are a superconductor having improved critical current density when exposed to high-energy neutron radiation and high magnetic fields, such as found in a compact nuclear fusion reactor, and a method of making the same. The method includes, prior to deployment in the exposure environment, irradiating a polycrystalline (e.g. cuprate) superconductor with ionic matter or neutrons at a cryogenic temperature to create 'weak' magnetic flux pinning sites, such as point defects or small defect clusters. Irradiation temperature is chosen, for example as a function of the superconducting material, so that irradiation creates the beneficial flux pinning sites while avoiding detrimental widening of the boundaries of the crystalline grains caused by diffusion of the displaced atoms. Such a superconductor in a coated-conductor tape is expected to be beneficial when used, for example, as a toroidal field coil in a fusion reactor when cooled well below its critical temperature.

Cryogenic radiation enhancement of superconductors

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Brookline, MA, United States of America

Dennis G Whyte