Commonwealth Fusion Systems and MIT’s Plasma Science and Fusion Center (PSFC) have demonstrated a magnet with a record-breaking 20 Tesla magnetic field. This is the core technology that they planned to create. They now have to mass produce it at ten times lower cost and assemble it into a net energy gain system by 2025. They have $1.8 billion in recent funding from Bill Gates, Jack Ma, Richard Branson and many other funds and investors. They previously had gotten over $200 million so they now have total funding over $2 billion. The 20-Tesla magnets will make the Commonwealth Fusion reactor 40 times smaller than the ITER tokamak reactor which will use 11-tesla magnets.

The 20 Tesla magnets will be used in SPARC. The SPARC demo unit began construction in 2021 and they hop eto demonstrate net energy gain for the first time in history by 2025.

Daniel Jassby, a retired physicist from the Princeton Plasma Physics Laboratory (PPPL), says PPPL’s Tokamak Fusion Test Reactor and the UK’s Joint European Torus, the only two fusion reactors in the world to have used tritium, took 10 years of experimenting with hydrogen and deuterium alone. If the warm-up period could be halved, SPARC’s tritium operation wouldn’t be likely to occur before 2032. The SPARC net gain demo reactor with construction completion targeted for 2025 will target 10 seconds bursts of power. Jassby is saying it will take years to get the system up to full operation and power levels. It would not be practical or reasonable to start work on the ten times larger commercial reactor before they learn if things are really working with the demo reactor.

SPARC would be the size of existing mid-sized fusion devices but with a much stronger magnetic field. SPARC plans to verify the technology and physics required to build a power plant based on the ARC fusion power plant concept. SPARC is designed to achieve this with margin in excess of breakeven and may be capable of achieving up to 140 MW of fusion power for 10 second bursts despite its relatively compact size. The resulting plasmas are expected to generate at least twice as much energy as is required to sustain themselves at high temperatures (200 million K), giving a fusion gain Q > 2, with an expected Q ≈ 11.

A 19 Tesla field is powerful enough to lift 403 Boeing 747s. Each of the SPARC demo systems would have 18 magnets and each magnet would have 166 miles of superconducting tape.

Commonwealth Fusion is trying to make a compact Tokomak with more powerful superconducting magnets. They wanted a commercial tokamak by 2033 but the current target is 2035 for a commercial tokamak. MIT spunout a tokamak fusion project into Commonwealth Fusion systems. They want to apply modular designs to high-temperature superconductors. They want to get to stronger magnets that will shrink the size and cost of the potential nuclear fusion reactor. Improved magnets would improve any nuclear fusion design that involves confinement of plasma. There is less science risk to this MIT approach but more technological risk. They are trying to accelerate the commercial use of high-temperature superconducting magnets and trying to contain their costs. Cost for superconducting magnets for past fusion projects have been $20 per watt but other applications have seen costs of $1.4 to $1.8 per watt.

They want to mass-produce superconducting magnets that are 2X the field strength of past strong magnets while bringing the cost per watt down.

The list of items below that Commonwealth fusion is targeting is from 2018.

There are 16 subsegments stacked for each magnet and 18 magnets are needed for the demo net gain system.

Commonwealth Fusion has more detailed project plans and peer-reviewed papers indicate the science is sound.

SPARC will use new high temperature superconducting (HTS) magnets to enable a similar performance as ITER but built more than 10 times smaller and on a significantly faster timeline.

The papers also predict that SPARC will very likely achieve a burning plasma for the first time on earth, meaning the fusion process will be dominantly self-heating. This is a major multi-decade goal of the world’s scientific community. In 2020, Commonwealth Fusion Systems (CFS) had a series of seven papers published and peer reviewed in a special edition of the Journal of Plasma Physics validating CFS’ approach to commercial fusion energy.

NOTE: Two years ago Tokamak Energy reported progress on a 20 Tesla magnet.The Commonwealth Fusion System 20 Tesla magnet is more complete for a fusion project. There are also more powerful magnets at the National Magnet lab. There is a 32 Tesla superconducting magnet. 42 Tesla hybrid magnet and 100 Tesla pulse magnet. Those magnets are for lab work and would be suitable for the Tokamak project.

SOURCES – Commonwealth Fusion Systems, Journal of Plasma Physics
Written By Brian Wang, Nextbigfuture.com