My general sense is that there’s more confidence in the plasma physics community that CFS will succeed than that Helion will succeed.
That is, indeed, an important indicator.
Otherwise, tokamaks being an old design works as an argument in the opposite direction for me (more or less along the following lines: tokamak design has been known for ages, and they still have not succeeded with it; perhaps an alternative and less tried design would have better chances, since at the very least it does not have the accumulated history of multi-decade-long delays associated with it).
(I guess, my assumption is that the mainstream plasma community has been failing us for a long time, feeding us more promises than actual progress for decade after decade, and that I would rather bet on something from the “left field” at this point, at least in terms of the chances to achieve commercial viability relatively soon, as opposed to the ability to attract funding or boost headcounts.)
Basically, yes, one thing we are comparing is their (Helion and CFS) respective 2024 and 2025 promises regarding Q>1, but more importantly from my viewpoint, Helion’s promise to actually ship electricity to the customers in 2028 does seem overoptimisitic, but perhaps not outrageously so, whereas with tokamaks, what’s our forecast for when they have a chance to actually ship electricity to the customers?
Tokamaks have been known for ages. We plausibly have gotten close to the best performance out of them that we could, without either dramatically increasing the size (ITER) or making the magnets significantly stronger. The high temperature superconducting[1] ‘tape’ that Commonwealth Fusion has pioneered has allowed us to make stronger magnetic fields, and made it feasible to build a fusion power plant using a tokamak the size of JET.
After SPARC, Commonwealth Fusion plans to build ARC, which should actually ship electricity to customers. ARC should have a plasma energy gain of Q~13, and engineering energy gain of about 3, and produce about 250 MWe. They haven’t made any public commitments about when they expect ARC to be built and selling electricity to the grid, but there has been some talk about the early 2030s.[2]
The higher temperature is not really what we care about. What we really want is higher magnetic field. These two properties go together, so we talk about ‘high temperature superconductors’, even if we’re planning on running it at the same temperature as before and making use of the higher magnetic fields.
You don’t need to have any insider information to make this estimate. Construction of SPARC is taking about 4 years. If we start when SPARC achieves Q>5 (2026?), add one year to do the detailed engineering design for ARC, and then 4 years to construct ARC, and maybe a year of initial experiments to make sure it works as expected, then we’re looking at something around 2032. You might be able to trim this timeline a bit and get it closer to 2030, or some of these steps might take longer. Conditional on SPARC succeeding at Q>5 by 2028, it seems pretty likely that ARC will be selling electricity to the grid by 2035.
That is, indeed, an important indicator.
Otherwise, tokamaks being an old design works as an argument in the opposite direction for me (more or less along the following lines: tokamak design has been known for ages, and they still have not succeeded with it; perhaps an alternative and less tried design would have better chances, since at the very least it does not have the accumulated history of multi-decade-long delays associated with it).
(I guess, my assumption is that the mainstream plasma community has been failing us for a long time, feeding us more promises than actual progress for decade after decade, and that I would rather bet on something from the “left field” at this point, at least in terms of the chances to achieve commercial viability relatively soon, as opposed to the ability to attract funding or boost headcounts.)
Basically, yes, one thing we are comparing is their (Helion and CFS) respective 2024 and 2025 promises regarding Q>1, but more importantly from my viewpoint, Helion’s promise to actually ship electricity to the customers in 2028 does seem overoptimisitic, but perhaps not outrageously so, whereas with tokamaks, what’s our forecast for when they have a chance to actually ship electricity to the customers?
Tokamaks have been known for ages. We plausibly have gotten close to the best performance out of them that we could, without either dramatically increasing the size (ITER) or making the magnets significantly stronger. The high temperature superconducting[1] ‘tape’ that Commonwealth Fusion has pioneered has allowed us to make stronger magnetic fields, and made it feasible to build a fusion power plant using a tokamak the size of JET.
After SPARC, Commonwealth Fusion plans to build ARC, which should actually ship electricity to customers. ARC should have a plasma energy gain of Q~13, and engineering energy gain of about 3, and produce about 250 MWe. They haven’t made any public commitments about when they expect ARC to be built and selling electricity to the grid, but there has been some talk about the early 2030s.[2]
The higher temperature is not really what we care about. What we really want is higher magnetic field. These two properties go together, so we talk about ‘high temperature superconductors’, even if we’re planning on running it at the same temperature as before and making use of the higher magnetic fields.
You don’t need to have any insider information to make this estimate. Construction of SPARC is taking about 4 years. If we start when SPARC achieves Q>5 (2026?), add one year to do the detailed engineering design for ARC, and then 4 years to construct ARC, and maybe a year of initial experiments to make sure it works as expected, then we’re looking at something around 2032. You might be able to trim this timeline a bit and get it closer to 2030, or some of these steps might take longer. Conditional on SPARC succeeding at Q>5 by 2028, it seems pretty likely that ARC will be selling electricity to the grid by 2035.