Nonlinear Plasma Dynamics in Microgravity: A High-Energy-Density Physics Platform

The Microgravity Nonlinear Plasma Platform (MNPP v2) is a structured theoretical framework for governed nonlinear plasma behaviour in microgravity environments. Version 2 expands the physical, mathematical, and governance architecture introduced in v1.0, refining the microgravity threshold, extending the instability‑growth model, and formalising the three‑state governance structure that constrains nonlinear evolution into Admissible, Marginal, and Runaway regimes. The MNPP identifies the gravity ceiling that limits terrestrial plasma research: buoyancy‑driven convection, wall‑bounded geometry, and gravity‑dependent transport distort or suppress nonlinear behaviours such as boundary‑free filamentation, long‑coherence density structures, and gravity‑sensitive instability families. MNPP v2 formalises the microgravity condition as g/g0≲3–8×10−4, where buoyancy timescales exceed electromagnetic evolution timescales by an order of magnitude. This regime is accessible on ISS‑class platforms, sounding rockets, and drop‑tower facilities. At the core of the framework is the Governance Ratio R=ωc/γnl, which classifies nonlinear evolution into three states: • Admissible (R > 10) — nonlinear growth fully governable • Marginal (1 < R < 10) — growth approaches control authority • Runaway (R ≤ 1) — termination mandatory MNPP v2 formalises the diagnostic latency constraint TLγnl<0.1, the five‑growth‑time recovery window, and the supervisory contraction loop that applies hysteresis as R approaches unity. These structures transform an open‑ended nonlinear system into a bounded, reproducible research platform. Version 2 also expands the falsifiability architecture, providing explicit predictions with measurable pass/fail criteria, required revisions if falsified, and defined diagnostic methods. Recent ISS PK‑4 results (2025) showing field‑aligned filament formation and long‑coherence density structures, along with 2025 PIC simulations of magnetised filamentation, provide supportive external context for the MNPP’s predicted nonlinear behaviours, without constituting validation of the full framework. The MNPP is connected to the Griffiths Canon propulsion and habitat architectures — the REMN rotating electromagnetic nozzle, the GNMT nuclear‑microwave‑thermal propulsion system, the Dual‑Ring Habitat, and the EM Curvature Theory — where several of the nonlinear plasma phenomena motivating the MNPP were first identified in boundary‑layer and exhaust‑coupling modelling. MNPP v2 extends this field‑governance philosophy into a dedicated microgravity plasma physics framework.