Center-Post Cooling

The center-post carries large current and absorbs neutron heating in a tiny volume, so cooling shares the same scarce space as conductor and shield.

Heat in the tightest place

The center-post dissipates resistive and nuclear heating in the smallest volume of the machine. That heat must be removed continuously or the conductor overheats, yet the coolant channels compete for the same inboard radius as the conductor and shielding. Cooling the center-post is a packaging problem as much as a thermal one.

The three-way squeeze

Every millimeter of the center stack is claimed by conductor, shield, or coolant. More coolant channel improves heat removal but leaves less room for conductor or shield; less coolant risks overheating. The design balances all three, and the compromise is one more reason the center-post accepts a short, replaceable life rather than an over-engineered permanent one.

• Resistive plus nuclear heating deposited in a small volume.
• Coolant channels compete with conductor and shield for radius.
• Coolant choice ties to the overall machine cooling scheme.
• Thermal limits interact with the neutron-damage limit.

Coupled to lifetime

Cooling and damage together set how hard the center-post can run and how long it lasts. A well-cooled center-post can carry its load, but neutron damage still limits its life to the ~0.01 fpy range. Cooling keeps it working within that life; it does not extend the damage-limited interval.

Coolant under irradiation

The center-post coolant itself operates under intense flux, so its chemistry, activation, and compatibility with the conductor matter as much as its heat-removal capacity. A coolant that carries heat well but activates strongly or corrodes the post under irradiation would trade one problem for another, so it is chosen as part of the whole center-stack design.

This page documents a design and simulation study, not a built machine. Construction begins Q2 2027; first-of-a-kind first tritium is targeted near 2030. Figures are computed, reproducible targets, not measurements.