Vacuum Vessel and Divertor
The vacuum vessel holds the plasma environment and the divertor handles exhaust heat and particles, both shaped by the compact geometry.
Two structural essentials
The vacuum vessel is the sealed chamber that maintains the high vacuum the plasma requires and forms the first structural boundary around it. The divertor is the region that receives plasma exhaust, heat and particles, and channels them away. Both are demanding in a compact, high-power machine.
The vessel
- Maintains operating vacuum with low outgassing
- Forms a precision structure sized to the compact spherical geometry
- Provides ports for heating, diagnostics, and maintenance access
- Carries loads and interfaces with blanket and magnets
The divertor
Exhaust heat handling is one of the hardest problems in any tokamak. The divertor must accept concentrated heat flux without failing. The negative triangularity of -0.30 is chosen partly to improve exhaust behavior, so the divertor design and the plasma shape are linked decisions.
Why the compact machine makes it harder
Concentrating 85.0 MW of fusion power in a compact machine concentrates the exhaust load. Less surface area is available to spread the heat, which raises the demand on divertor materials and geometry. This is a genuine engineering challenge the design must meet, not assume away.
The vessel and divertor are designs for a machine not yet built. Their performance is verified during commissioning and operation; the vessel is one of the long-lead pacing items that drives the build schedule.