The DEC Efficiency Budget

Rolling every stage, loss, and handoff into one accounting shows where the energy goes and what limits the train.

One budget for the whole train

An honest picture of DEC performance is not a single stage efficiency but a budget: start with the charged-particle energy entering the train and subtract each loss on the way to the bus. Because the stages cascade, a loss in one place may be recovered later, so the budget must be tallied in order, stage by stage, with the residual heat and neutron share accounted separately.

The line items

• TWDEC: capture fraction, deceleration completeness, RF and rectification losses.
• MHD: ohmic dissipation, electrode drops, Hall short-circuit, end effects.
• Thermionic: space-charge-limited current, radiation between electrodes.
• Collectors: interception, secondary-electron leakage, sheath drops.
• Power electronics: DC-DC conversion and inverter losses.
• Rejected: neutron thermal share (~5.44%) and radiation, handled by cooling.

Reading the budget

The budget's value is that it shows where to invest. If interception dominates, work on grid transparency and beam optics; if ohmic loss dominates, raise the MHD field or run hotter inlet; if secondary electrons cost the most, improve suppression and coatings. It converts a vague ‘efficiency’ into a prioritized engineering list.

Status

Every number in this budget is, at present, a modeled quantity in a design-and-simulation study. The line-item structure is firm and physically grounded; the values await the burner test unit around 2032. Presenting it as a budget — rather than a single headline efficiency — is the honest way to describe a converter that has not yet run on a plasma.