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We actually do have commercially available superconductors that support much stronger magnetic fields than what ITER is able to do. I don't think it's 100x, bu

We actually do have commercially available superconductors that support much stronger magnetic fields than what ITER is able to do. I don't think it's 100x, but it doesn't have to be. Tokamak output scales with the fourth power of magnetic field strength. Double the field, 16X the energy output. CFS and Tokamak Energy are building tokamaks with these. Tokamak output also scales with the square of reactor size, which is why ITER is so big. These new reactors can be much smaller for the same output, so they'll be much faster and cheaper to build. The CFS design is about the size of JET, which was built in four years, with three of those being just for the building.

UltraSane 2y ago
Why doesn't ITER use the better superconductors?
- DennisP 2y ago
  Because they completed the initial design in 2001, and broke ground in 2007. The superconductors became available in the early 2010s.
  - UltraSane 2y ago
    They should have redesigned it. Spending so much money on a fundamentally inferior design is pretty stupid.
    - rcxdude 2y ago
      That's a good way to never actually complete a big project.
      - UltraSane 2y ago
        It is already incredibly far behind schedule.
        rcxdude 2y ago
        And your suggestion would put it even further behind.
pfdietz 2y ago
It can't be 100x. In designs like ARC the magnets are up against limits not from the superconductors, but from the structures needed to resist JxB forces. The majority of the mass of the ARC reactor is in these steel structures. Much progress beyond that would involve significant increases in strength of materials, and even then the strength needed scales as B^2. 100x ARC would be ~2000 T. The magnetic pressure of such a field would be about 100x the detonation pressure of TNT. Experimentally, fields of such magnitude could only be produced very briefly in devices that near-instantly explode (for example, devices driven by intense laser pulses that produce large charge separations.) > Tokamak output also scales with the square of reactor size ITER is big because it wouldn't work at all if it were smaller (at the magnetic fields involved). Output scaling as (linear dimensions)^2 means you want your reactor to be as small as possible, to maximize power/volume. Square-cube law in operation. The higher magnetic field in HTSC tokamaks allows then to be smaller. Volumetric power density is still poor, though, just not as terrible as ITER.

UltraSane 2y ago

Why doesn't ITER use the better superconductors?

DennisP 2y ago
Because they completed the initial design in 2001, and broke ground in 2007. The superconductors became available in the early 2010s.
- UltraSane 2y ago
  They should have redesigned it. Spending so much money on a fundamentally inferior design is pretty stupid.
  - rcxdude 2y ago
    That's a good way to never actually complete a big project.
    - UltraSane 2y ago
      It is already incredibly far behind schedule.
      - rcxdude 2y ago
        And your suggestion would put it even further behind.

pfdietz 2y ago

It can't be 100x. In designs like ARC the magnets are up against limits not from the superconductors, but from the structures needed to resist JxB forces. The majority of the mass of the ARC reactor is in these steel structures. Much progress beyond that would involve significant increases in strength of materials, and even then the strength needed scales as B^2. 100x ARC would be ~2000 T. The magnetic pressure of such a field would be about 100x the detonation pressure of TNT. Experimentally, fields of such magnitude could only be produced very briefly in devices that near-instantly explode (for example, devices driven by intense laser pulses that produce large charge separations.) > Tokamak output also scales with the square of reactor size ITER is big because it wouldn't work at all if it were smaller (at the magnetic fields involved). Output scaling as (linear dimensions)^2 means you want your reactor to be as small as possible, to maximize power/volume. Square-cube law in operation. The higher magnetic field in HTSC tokamaks allows then to be smaller. Volumetric power density is still poor, though, just not as terrible as ITER.