Vacuum & Cooling of the Collectors

The DEC train lives in high vacuum and its surfaces run hot, so vacuum integrity and closed-loop cooling are shared, load-bearing systems.

Two services the whole train shares

Every converter in the train needs the same two support services: a clean high vacuum so beams travel and high voltages hold, and cooling so hot surfaces survive. Because the stages share one vacuum envelope and a common thermal path, these are designed as train-wide systems rather than per-stage add-ons.

Vacuum

• A high vacuum keeps beams from scattering on residual gas and preserves high-voltage standoff.
• Pumping must handle gas loads from the plasma exhaust and any outgassing surfaces.
• A pressure excursion can both scatter the beam and trigger breakdown, so vacuum is continuously monitored.

Cooling — closed and dry by design

The heat the collectors absorb — intercepted ions, secondary particles, absorbed radiation, and the neutron thermal share — is carried away by a closed cooling loop. Crucially, this loop can be dry-cooled: because the total heat to reject is a small fraction of output, it does not require the large evaporative water use of a steam-cycle condenser. This is where the near-zero-water claim is realized in hardware.

Why they are load-bearing

Neither system is optional. Lose vacuum and the beams scatter and the high voltage arcs; lose cooling and the electrodes overheat and erode. Both must be reliable for the burner to run continuously, which is precisely the firm, always-on operation MetroVolt promises. Their reliability is part of the maintenance and availability picture discussed later in this section.