Mesoscopic Test of Conditional Space Reactivity in a Boundary-Free Rotating Plasma Ring

This preprint proposes a laboratory-scale test of conditional space reactivity within the space–matter–motion (RMB) framework. The work does not introduce a global modification of gravity nor additional propagating degrees of freedom. Instead, it formulates a falsifiable hypothesis for a weak, local backreaction of space to collectively organized, coherent rotation in dissipative, non-equilibrium systems. Boundary-free rotating plasma rings generated in pulsed-power experiments are identified as a realistic testbed. Using parameters from recent MAGPIE/RPX experiments, a dimensionless mesoscopic order parameter is defined and shown to reach values of order unity under experimentally accessible conditions. The resulting prediction is a small but systematic shift in plasma stability thresholds at the level of 10⁻⁴–10⁻³, detectable through differential ON/OFF measurements. A null result yields a sharp upper bound, rendering the hypothesis explicitly falsifiable. The work is intended as a technical note bridging the RMB cosmological framework to laboratory-scale tests and does not address cosmological gravity, gravitational-wave propagation, or large-scale structure.