The H₂EM Thruster is a microgravity‑stable, electromagnetically governed hydrogen‑combustion propulsion system designed for deep‑space vessels assembled in orbit. It combines three domains—on‑demand water cracking, EM‑stabilised hydrogen combustion, and an optional plasma/REMN acceleration mode—into a unified architecture capable of delivering both high thrust and ultra‑high specific impulse. As stated in the attached document, the system “produces hydrogen and oxygen streams that are fed into an electromagnetically governed combustion chamber,” enabling sustained, stable operation in microgravity.

1. Propellant and Feed Architecture

Water is the sole propellant. It is cracked on demand using microwave excitation, producing high‑purity hydrogen and oxygen without the need for stored cryogenic propellants. The attached document notes that “water is cracked on demand via microwave excitation… producing hydrogen and oxygen streams” . This cracking process is fully microgravity‑compatible: a pressurised feed system, positive‑displacement metering, and capillary‑wicking baffles ensure stable flow without reliance on gravity. Gas‑liquid separation is handled by a compact centrifugal micro‑separator, guaranteeing that only pure hydrogen enters the combustion or plasma stages.

2. EM‑Governed Hydrogen Combustion (Primary Mode)

The primary propulsion mechanism is hydrogen combustion governed by electromagnetic field architecture. The combustion chamber contains three EM‑defined zones: an ignition zone, a flame‑stabilisation zone, and a suppression boundary. As the document states, “EM‑stabilised ignition, flame anchoring, and suppression zones enable sustained high‑mass‑flow hydrogen combustion in microgravity.” This governance layer eliminates flashback, blowout, and mixed‑gas instabilities that traditionally prevent hydrogen combustion in microgravity.

Combustion mode delivers the bulk of mission Δv. With Isp in the 400–450 s range, high mass flow, and full EM stability, the H₂EM Thruster provides reliable, high‑thrust propulsion for interplanetary transit, orbital manoeuvres, and long‑duration burns.

3. Plasma/REMN Mode (Secondary High‑Isp Extension)
For missions requiring extreme efficiency or rapid Δv injection, the H₂EM Thruster transitions into a plasma acceleration mode. Partially dissociated hydrogen from the cracking module enters an EM‑governed dissociation core, producing a controlled mixture of H, H₂⁺, and H⁺ optimised for electromagnetic acceleration. This plasma is then accelerated through a wall‑less Rotating Electromagnetic Nozzle (REMN), which uses rotating and static magnetic fields to confine, collimate, and accelerate the exhaust.

The attached document describes this as “a wall‑less rotating EM nozzle… enabling cruise Isp (~10,000 s) and REBCO burst Isp (500,000–1,000,000+ s).” This dual‑regime capability allows the same engine to operate as a high‑thrust combustor or an ultra‑efficient plasma engine.

4. Power and Modularity

The architecture is powered by Prometheus‑class fission reactors, with optional clip‑on reactor pods that expand available power without redesign. Water pods attach the same way, providing both propellant and radiation shielding. This modularity enables long‑range missions, rapid refuelling, and scalable power budgets.

5. Mission Context

Four H₂EM engines arranged in a 2×2 cluster feed twin REMN nozzles, providing thrust vectoring, redundancy, and burst‑mode sequencing. The system is designed for deep‑space vessels assembled in orbit, with all Δv requirements achievable in combustion mode alone. Plasma/REMN mode extends the envelope but is not required for mission completion.