H₂EM‑Agri is a field‑governed atmospheric nitrogen‑fixation architecture that produces nitrate fertiliser, green ammonia, or ammonium nitrate on demand without high‑pressure vessels, cryogenics, or centralised Haber–Bosch infrastructure. It extends the unified electromagnetic governance framework of the Griffiths Canon to nitrogen chemistry, using closed‑loop electron‑energy‑distribution‑function (EEDF) control to selectively drive N₂ → NOx and N₂ + H₂ → NH₃ at atmospheric pressure. As the document states, the system “applies closed-loop EEDF tuning within a governed reaction volume to selectively drive N₂ → NOx at efficiencies substantially exceeding legacy ICP and RF arc systems.”

The architecture comprises two co‑deployed subsystems — the NOx route and the H₂EM‑NH₃ Plant — both governed by DIGSP and sharing the same EM field topology used across the H₂EM family. The NOx route produces nitric acid and nitrate solution; the NH₃ route produces green ammonia via plasma‑catalytic activation. The two streams can be combined to produce ammonium nitrate (34% N), enabling a complete distributed fertiliser production suite.

Mechanistic Innovation — EEDF Governance

The core differentiator is closed‑loop EEDF shaping. Conventional plasma fixation is open‑loop: energy is dissipated as heat, and selectivity is poor. H₂EM‑Agri actively shapes the EEDF to concentrate electrons in the 2–3 eV vibrational‑excitation window, matching the σᵥ(E) peak for N₂ vibrational ladder activation. This enables selective bond activation at far lower thermal load than thermal Zeldovich chemistry. The document notes that the system “suppresses the high-energy ionisation tail (E > 8 eV) and enhances the 2–3 eV window,” enabling non‑thermal fixation with high selectivity.

NOx Route — Nitrate and Nitric Acid Production

Filtered ambient air enters a governed plasma reaction volume where N₂ vibrational excitation and controlled Zeldovich kinetics generate NO and NO₂. A phase‑aligned quench locks the NO/NO₂ ratio before recombination, requiring >10⁶ K/s cooling rates. The quench is synchronised to the MW drive phase with ±50 µs precision. A counter‑current absorption column converts NOx to nitric acid or nitrate solution with ≥95% absorption efficiency. Product concentration is tunable from 3–20% by mass.