Commonwealth Fusion Systems
MIT Plasma Science & Fusion Center

An exclusive behind-the-scenes-view of the HTS Magnet Demonstration

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Magnet FAQ

General information — The big picture

What is being demonstrated?

We have designed and built a large-bore, full-scale high-temperature superconducting magnet suitable for fusion devices. It will be the most powerful superconducting magnet ever built for fusion applications. The magnet is a key technology for SPARC, which will be the first machine to create and confine a plasma that makes net fusion power. The successful magnet demonstration is the last piece of the puzzle — it will mean that we have all the pieces to build SPARC

Why are magnets so important?

To make fusion work, the fuel must be heated to temperatures above 100 million degrees. Matter in that state is called a plasma – where the particles have net electric charge. To be kept hot, this plasma must be very well insulated from ordinary matter. Fusion devices use magnetic fields to provide the thermal insulation that is required. The stronger the magnetic field, the stronger the confining force on the charged particles in the plasma, the better the insulation, which enables a much smaller, better performing fusion device.

What is special about this magnet?

It incorporates important innovations in design. Unlike existing fusion magnets it is built using a new conductor HTS (high temperature superconductors). Compared to conventional superconductors (LTS Low temperature superconductors) our magnet can carry more current even when embedded in a strong magnetic field. It incorporates important innovations in design which together with the use of HTS allows us to build smaller more powerful magnets.

What would it mean for fusion?
Why is this important?

Allows fusion devices to be made smaller, faster, cheaper. Puts us on a faster path to commercializing fusion energy in time to impact global warming.

Is this the magnet that will be used in SPARC?

Not quite: it is approximately 80% the size of the magnets that will be used in SPARC. Designed to prove out the SPARC design.

What are the differences?

More about the magnet

About HTS

What is a superconductor?
What is HTS?
Why hasn’t it been used to make magnets before?

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