The Vacuum Vessel

The vacuum vessel is the sealed chamber that holds the plasma in high vacuum and forms the first structural boundary around it.

The plasma's container

Fusion plasmas exist only in high vacuum: any residual gas would radiate away the energy and quench the reaction. The vacuum vessel is the sealed, pumped chamber that maintains that vacuum, gives the plasma-facing components and blanket a structure to mount to, and forms the first confinement boundary for tritium and activated material.

A demanding shape and duty

In a spherical tokamak the vessel wraps closely around the plasma and the center stack, so its inboard wall is tight and its shape complex. It must hold vacuum against atmospheric pressure, carry electromagnetic loads from plasma events, tolerate heat and neutron flux, and provide ports for heating, fueling, pumping, and diagnostics, all while remaining leak-tight over the machine's life.

Interfaces

The vessel is the hub that everything else connects through. The first wall and breeding blanket sit inside it; the divertor mounts at the bottom; neutral beams and RF launchers enter through ports; vacuum pumps and tritium-handling lines tie in; and remote-handling tooling reaches the internals through access points. Because the interior becomes activated, most in-vessel work is done remotely, and the vessel's ports and layout are designed around that constraint from the start.

• Maintains high vacuum and forms the first confinement boundary
• Carries plasma-event electromagnetic and thermal loads
• Provides ports for heating, fueling, pumping, and diagnostics

This page describes a design and simulation study, not a built machine. Construction begins Q2 2027; first-of-a-kind first tritium is targeted near 2030.