KRONOS FUSION ENERGYWHITEPAPER 066 / 104
Direct Energy Conversion & Power Handling

Bracketing the Uncertainty: Trubnikov, AFJ, and the Optically-Thin Bound

The burner does not trust one synchrotron formula — it publishes the whole bracket, including the one that fails.

The synchrotron loss that decides the burner's ledger is not known to one number. The design brackets it across published treatments: 57.9 MW (Trubnikov), 100.1 MW (the AFJ fit used at the reference point), and a 3,038 MW strict optically-thin bound — under which the design never closes.

The science

Synchrotron loss depends on how much emitted radiation is reabsorbed by the plasma. The three treatments span an enormous range: the optically-thin bound assumes no reabsorption and gives 3,038 MW — 15.6x the fusion power — at which point the machine cannot close at any parameter combination. The reference uses the AFJ fit at 100 MW; Trubnikov is lower still.

Why it matters

Publishing the full bracket, including the bound under which the design fails, is the opposite of cherry-picking. It tells the reader exactly how much of the burner's viability rides on reabsorption — which is precisely the quantity no one has measured at these conditions.

The numbers

Trubnikov57.9 MW
AFJ (used)100.1 MW
Optically-thin bound3,038 MW (never closes)
Optically-thin vs fusion15.6x fusion power
Decideswhether the design closes
Straight answersThe synchrotron bracket is published in full, including the failing bound; the AFJ fit is used 8% outside its fitted temperature range at some window points, and it decides the answer — stated plainly as the dominant uncertainty.
Kronos is the fusion company that shows its work. Every figure here traces to the openly deposited Kronos simulation programme and design-point records (CC BY 4.0). Read the series, run the code, check us. — All whitepapers
Conceptual design and simulation study; no machine has been built. Quantitative values are simulation-derived and carry the feasibility gates named in the text; superseded values are kept in the record with era labels. This document is informational and is not an offer of securities. © 2026 Kronos Fusion Energy, Inc. · Los Angeles, California.
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