Kinetic turbulence drives MHD equilibrium change via 3D reconnection

Cross-scale coupling from magnetohydrodynamics(MHD) to non-MHD scales is an important key in interpreting observations of explosive events in nature like solar flares and geomagnetic storms. Experiments and observations also link it to the emergence of energetic particles and X-rays. However, how such multi-scale physics affects the abrupt onset of reconnection remains an open, unresolved question. Here, we report observations from laboratory experiments involving two flux ropes with electron beams that induce magnetic turbulence and then abruptly merge into a single structure, altering the magnetic topology in the MHD regime. Two separate electron beams are launched along magnetic field lines and form individual flux ropes with a drift velocity higher than the ambient Alfvén velocity, effectively driving magnetic turbulence via beam-driven instabilities, inferred from the increased level of turbulent power spectrum. Experimental observations, including the appearance of energetic particles, increased ion temperature, and changes in the characteristics of flux ropes, suggest that beam-driven turbulence drives 3D reconnection. 3D particle-in-cell simulations are performed which successfully reproduce the key aspects of the experiment. These results directly illustrate how non-MHD kinetic processes progress through multiple scales to induce global MHD changes.