Peak Field and On-Axis Field
Kronos quotes the breeder's 16.84 T peak field and 8 T on-axis field distinctly, because peak and on-axis field are different quantities and conflating them overstates the magnet.
Two fields, two meanings
Magnetic field in a tokamak is not a single number. The peak field is the highest field the conductor sees, at the magnet; the on-axis field is the field at the plasma centre. For the breeder (Hyperion) these are 16.84 T peak and 8 T on-axis. Quoting one where the other belongs either flatters or undersells the magnet, so we always say which.
Why the distinction is load-bearing
- Peak field sets the engineering demand on the conductor and structure
- On-axis field is what the plasma physics actually experiences
- A high peak field quoted as on-axis would overstate confinement performance
- A low on-axis field quoted as peak would understate the magnet challenge
The honest presentation
When we cite field, we name the location: 16.84 T at the coil, 8 T at the axis. Both are design targets from the frozen canon, not measured values — the magnets are not yet built. Keeping the pair distinct lets a magnet engineer and a plasma physicist each read the number that is relevant to them without being misled.
It is a small discipline that prevents a common sleight of hand: using whichever field number makes a given point look strongest.