A bifluidic model formalism analyzing sheath plasma resonance in inverted fireballs

The sheath plasma resonance (SPR) in an inverted fireball (IFB) system is semi-analytically investigated in the framework of a generalized hydrodynamic isothermal model formalism comprising of electron–ion fluids. It incorporates the constitutive ionic fluid viscosity, inter-species collisions, and geometric curvature effects. The SPR stability is investigated for an anodic (hollow, meshed) IFB for the first time against the traditional cathode-plasma arrangements of regular electrode (solid, smooth) fireballs. The SPR develops in the vicinity of a spherical electrode enclosed by a plasma sheath amid a given electric potential. A generalized linear quartic dispersion relation (DR) with diverse plasma multi-parametric dispersion coefficients is methodically derived using a standard spherical linear normal mode analysis. The mathematical construct of the DR roots confirms that there exists only one feasible nonzero frequency mode (emerging in the IFB). This DR root is studied both analytically and numerically. This consequent SPR creates trapped acoustic fluctuations in the IFB plasmas because of the internal reflections at the sheath plasma boundary. Also, sensible parametric changes in the SPR characteristics, with both plasma density and viscosity, are seen. A local condition for the SPR excitation and its subsequent transition to collective standing wave-like patterns in the IFBs is illustratively analyzed. A fair corroboration of our investigated results with the previously reported SPR experimental observations of standing wave-like eigenmode patterns (evanescent) validates the practical reliability of our proposed study.