Hyperion Neutron Shield
The neutron shield sits behind the blanket to protect the vacuum vessel, the superconducting coils, and the structure from radiation.
Stopping what the blanket misses
Even a thick breeding blanket does not stop every neutron. The neutron shield is the layer outboard of the blanket whose job is to absorb the remaining flux before it reaches the components that cannot tolerate it, above all the superconducting magnets.
Why the magnets need it
- Superconductors lose performance and are damaged by neutron irradiation over time.
- The magnets are cold; neutron heating adds to the cryogenic load that must be removed.
- Insulation and structure degrade under accumulated dose.
- The inboard side is hardest to shield because the center stack is so tight.
The inboard squeeze
On a spherical tokamak the inboard shield competes for the same scarce radius as the TF conductor and the solenoid. There is only so much room in the center stack, so inboard shielding is one of the tightest trade-offs in the machine: enough to protect the conductor for its intended life, thin enough to keep the geometry compact. This trade-off is a recurring subject of the Hyperion engineering work.
In the model
The shield appears in the cutaway as the layer between the blanket and the vacuum vessel, with its own thickness callout. Selecting it highlights how it wraps both the outboard blanket and, more thinly, the inboard center stack.
What it protects
The shield's purpose is defined by what sits behind it: the vacuum vessel and the toroidal-field coils. See the breeding blanket ahead of it.