Dynamic Mode Decomposition for data-driven analysis and reduced-order modelling of ExB plasmas: II. dynamics forecasting

Today, reliable, predictive, and generalizable reduced-order models do not exist for plasmas. There are at least two reasons for this status quo: first, the classic conservation equations derived from the moments of the plasma kinetic equation [1] do not include the important effects of microscopic plasma instabilities and oscillations on the electrons' momentum and energy transport [2]. Second, despite years of effort and several approaches pursued [3]-[7], rigorous and generalizable closure models for the conservation equations are still to be established so that the effects of the kinetic phenomena and processes such as the cross-field electrons' transport can be selfconsistently resolved in reduced-order simulations based upon the conservation equations for the plasma. Nonetheless, the need for self-consistent, interpretable reduced-order plasma models is critical for scientific and industrial advancements alike. From an academic perspective, the availability of such models can enable answering the so-far unresolved questions in the physics of cross-field plasmas, particularly with regards to the excitation and evolution of the plasma instabilities and turbulence as well as their interactions with plasma species that, for example, can result in enhanced transport of the particles and energy across the magnetic field. From an applied point of view, reliable reduced-order models can lead to the prediction and control of the plasmas, paving the way for more efficient technological solutions and novel plasma applications. The above issues, although rather different in nature and extent, also exist in other research fields such as fluid mechanics. Attempts to establish closure models for Navier-Stokes system of equations to incorporate the effects of unresolved turbulence, for example, have been rigorously pursued for decades in order to achieve fully generalizable predictive models of the fluid systems [8]. Nonetheless, the efforts in fluid dynamics to the above end have not been fully successful either.