CFS begins preparing a home for our 100 million degree fusion plasma

[OKIsItJustMe]

https://blog.cfs.energy/cfs-begins-preparing-a-home-for-our-100-million-degree-fusion-plasma/

May 14, 2026 by Alex Graziano [Senior Content Marketing Manager]

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The second half of the vacuum vessel for our SPARC demonstration fusion machine has arrived, allowing us to begin equipping it and its counterpart to host the most intense conditions in the solar system. We’ve now begun the hard work of fitting out the vacuum vessel halves for use by measuring them carefully, using those measurements to precisely make the components that’ll face the fierce plasma temperatures, and adding the diagnostic equipment to control and understand SPARC.

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The vacuum vessel is the 96-ton, donut-shaped steel chamber at the heart of SPARC. Once we’ve fully equipped the two halves, welded them together, and begun SPARC operations, our vacuum pumps will make it as airless as outer space. When SPARC operations begin in 2027, we’ll puff in a bit of fusion fuel and use radio waves to heat it into an energetic cloud of particles called a plasma. We’ll heat that plasma to 100 million degrees Celsius, holding it in place with powerful magnets so it fuses and releases more energy from fusion than it took to heat it. This net fusion energy milestone, called Q>1 in scientific circles, is a crucial step to prove our fusion energy approach works.

With SPARC’s cryostat base already installed, and two of our D-shaped toroidal field (TF) magnets now in place — more to come soon — SPARC is nearly 75% complete and is starting to look like an actual tokamak.

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Eventually, each vacuum vessel half will be housed within a set of nine D-shaped toroidal field magnets arranged in a semicircular array, then each of those assemblies will be mated together. But before any of that can happen, both halves of the vessel need to be inspected, cleaned, measured, and outfitted with plasma-facing components and diagnostic systems.

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[ahnakneemoose]

1. Really Great Video - Thank You OKIsItJustMe (n/t)

[OKIsItJustMe]

5. My pleasure!

Happy Monday!

[LPBBEAR]

2. One Million Degrees!?

Insane.

Research and testing for projects like this should be conducted in space far away from Earth. This is just insane.

[eppur_se_muova]

4. No need. The amount of material at this temperature is relatively small.

Temperature is not a measure of the total energy content, but of the concentration of energy. A large amount of energy in a very small mass gives an enormous temperature, and energy tries to diffuse away more rapidly the more concentrated it becomes, so it can cool off very quickly if it contacts any other matter -- including air.

Technically, temperature is a measure of what is called "number energy density", or the average energy per particle. This is an intensive property, which can be measured at a single point; the total amount of heat in a sample is an extensive property, i.e. it is evaluated over the whole sample and thus depends on the sample size. It's like the difference between pressure (intensive) and force (extensive) -- your dancing partner may not weigh all that much (moderate force) but put all that weight into the tip of a stiletto heel and the resulting high pressure can be quite harmful !

[OKIsItJustMe]

6. So, researchers have been producing fusion in Tokomaks (like SPARC) for a lifetime

https://en.wikipedia.org/wiki/Tokamak#First_tokamaks

The key is that (to date) they have not produced more energy than was put into them to power the fusion reaction. If all goes according to plan, SPARC will achieve that. It will not, however, produce a useful amount of energy. SPARC is the prototype.

The plan calls for ARC — a larger scale reactor — to generate electricity for the grid.

https://blog.cfs.energy/going-to-the-grid-cfs-applies-to-plug-our-first-arc-fusion-power-plant-into-pjm/

Going to the grid: CFS applies to plug our first ARC fusion power plant into PJM

April 28, 2026by Ben Byboth [Director, Power Business Development & Strategy]

Commonwealth Fusion Systems (CFS) has pioneered another step of the journey to fusion energy, applying to connect our first ARC fusion power plant in Chesterfield County, Virginia to the world’s largest wholesale electricity market, PJM Interconnection.

Compared to other steps on the fusion commercialization path — developing our technology, raising our funds, building our supply chain — it might not be obvious why requesting a spot on the power grid is so important. So I’d like to explain what we did and why it’s a big deal.

When we submitted a Generation Interconnection Request last week with PJM, we became the first fusion power plant developer to take this definitive step with a major grid operator — pairing the breakthrough technology of fusion with real-world infrastructure to power our future. This is a bridge from the science phase of fusion energy to the real-world impact.

Although fusion energy on the grid is new, the path we’re taking to get it there isn’t. We’re applying for a home on the PJM system just like any other power plant must, and in many ways, our fusion power plant will look just like the 1,400 or so other interconnected generators already there. It’ll be just another source of electricity, except that instead of using the heat from burning coal or natural gas to boil water for a steam turbine, we’ll use the heat from the fusion process. That means our ARC plants can be the new building blocks for the grid, swapping in for older decommissioned coal or gas plants and arriving where demand is growing, capitalizing on the same grid infrastructure that exists today.

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[littlemissmartypants]

3. Video

K&R