Integrating the DEC Train
The stages only deliver system efficiency if the beam is handed cleanly from one converter to the next through shared magnetic and vacuum geometry.
The handoff problem
On paper the train is a tidy cascade; in hardware, the challenge is the handoffs. The plasma exhaust must be shaped by the magnetic field into a beam the TWDEC can bunch, the residual must arrive at the MHD channel with the right flow and conductivity, and what heats the surfaces must be presented to the thermionic emitters. Each interface is a place where energy or beam quality can be lost, so integration is as important as any single stage's physics.
What must be shared
- Magnetic geometry: one field profile both confines the plasma and steers the exhaust through each converter.
- Vacuum envelope: the whole train sits in a common high vacuum — a leak or pressure rise degrades every stage.
- Control: stage voltages, RF phase, and channel loads must be coordinated so one stage's operating point does not spoil the next.
- Thermal path: heat rejected by upstream electrodes becomes the input to the thermionic stage.
Diagnostics at every interface
Because losses hide at the handoffs, the train is instrumented at each interface: beam current and energy spectrum entering TWDEC, flow and conductivity into the MHD channel, surface temperatures on the thermionic emitters, and residual power to cooling. These measurements close the efficiency budget and tell operators which stage to tune.
Status
Individual stages rest on established physics; the integrated train on a real D-3He plasma is the central objective of the burner program. The ~2032 test unit is designed to demonstrate the handoffs working together — not just each converter in isolation — which is the difference between a set of components and a generator.