The Gatchina discharge - a high-voltage capacitive pulse discharge between an electrode and a water surface - can reproducibly produce self-luminous spherical plasmoids (detached, wall-free volumes of ionized gas) 10-20 cm across that persist for up to about 1 s after the current ceases and exhibit several properties attributed to natural ball lightning: nonthermal glow, interaction with conductors but not dielectrics, an uncompensated electric charge, and passage through openings smaller than their diameter. Shabanov's 2019 Physics-Uspekhi review, which consolidated this work, left the central physics open: no mechanism derived from discharge microphysics explains the formation, charge and envelope structure, stability, and lifetime of the objects, and its proposed electrostatic model and ball-lightning-analog claim were immediately contested (a charge estimate implying surface fields about 100 times the air breakdown field, disputed energy budgets, and lifetime and energy-density shortfalls relative to natural events). Follow-up literature through 2026 has deepened characterization - leader/streamer imaging, field-perturbation and charge-sign tests, toroidal-vortex visualization, aerosol and OH-radical measurements, and a 2026 claim of a thin negatively charged shell - but has produced no validated theory and no community consensus. The problem posed is to establish, by predictive theory plus decisive noncontact diagnostics, the physical mechanism of these long-lived plasmoids - formation, structure, stability, and regime boundaries - to the level needed to settle the contested charge magnitude, energy budget, and the ball-lightning analogy itself.

Background

Ball lightning - a free-floating, luminous, roughly spherical object, typically 5-50 cm across, reported during thunderstorms and persisting for seconds to tens of seconds - is a long-standing unsolved problem of atmospheric electricity: tens of thousands of eyewitness reports exist, yet no accepted physical theory explains how such an object stores energy and remains stable in open air, and candidate hypotheses number in the hundreds.

In 2000, at Gatchina (Petersburg Nuclear Physics Institute, Russia), a laboratory route to similar objects was discovered. The Gatchina discharge is a pulsed high-voltage discharge between a graphite electrode and the surface of an electrolyte (electrically conducting water solution) in open air, driven by a capacitor bank of a few kilojoules with a current pulse of order 10-100 ms set by the commutation (switching) device. A glowing plasma sheet and jet phase over the water is followed by detachment of a self-luminous sphere that keeps its size and glow for up to about 1 second with no external power supply, with near-100% reproducibility on the originator's facility. Such detached ionized-gas volumes confined without material walls are commonly called plasmoids.

These laboratory objects exhibit unusual properties that motivated the ball-lightning comparison. They interact with conductors - a suspended nichrome (nickel-chromium alloy) ring placed inside one melts at a single site - while low-melting dielectric fibers embedded in them remain unchanged, indicating a bulk temperature below about 200 degrees C despite a visible glow whose color temperature is 1000-2000 degrees C (nonthermal luminescence). They carry an uncompensated electric charge (a net charge not neutralized by opposite charges, inferred from deflection by electric fields and from corona observations, a corona being the faint local ionization glow that develops at the surface of a strongly charged body). They can pass through openings about half their diameter, and their apparent color changes with illumination conditions. Mass spectrometry by independent groups showed that the discharge synthesizes a rich set of ions and molecules - for example NH3_3 from atmospheric nitrogen and hydrogen, demonstrated by substituting heavy water D2_2O - which the original author takes as the building material of a thin insulating envelope, a dielectric skin visible in filtered photographs, that separates the charged interior from the surrounding air. Independent laboratories (Eindhoven/Augsburg, New Mexico, Illinois, and others) reproduced plasmoid production over water with shorter lifetimes, typically 0.2-0.5 s, and a parallel tabletop approach generated confined plasma balls along laser-guided discharge channels, but none of these produced an accepted mechanism either.

Shabanov's 2019 review proposed a qualitative model: the head of a stopped lightning leader (the leader being the hot conductive channel of a propagating discharge, fed at its tip by cold branched ionization channels called streamers) delivers charge into a growing envelope of synthesized polar molecules; the Coulomb repulsion of the enclosed like charges is balanced by the mechanical pressure of this polarized dielectric shell. An electrostatic scaling Q=2W/φQ = 2W/\varphi, with WW the statistically averaged ball-lightning energy of about 6 kJ and φ\varphi the averaged leader potential of about 30 MV, reproduces the statistically observed mean diameter of natural ball lightning (about 23 cm) and yields Q≈4×10−4Q \approx 4\times10^{-4} C. The model is explicitly hypothetical: it is not derived from discharge microphysics, gives no quantitative stability or lifetime prediction, and no map of the existence regimes in the facility parameter space exists. The review itself concedes the main empirical gaps: existing experiments do not determine the charge-carrier structure inside the envelope, the plasma-chemical kinetics of envelope formation are unquantified, and new noncontact diagnostics (for example electric-field probes) are required. The theory distinguishes two extreme existence modes - high-charge, low-temperature, envelope-stabilized objects versus low-charge, hot, thermally inflated and short-lived ones - with unmapped intermediate regimes.

The model's central numbers were immediately contested. Shmatov (2020) showed that a 4×10−44\times10^{-4} C charge on a sphere of this size implies an electric field at its surface about 100 times the air breakdown field, that the envelope-pressure balance uses orientation polarizability outside its range of validity, and that the laboratory objects fall short of natural ball lightning in lifetime (about 1 s versus tens of seconds) and energy density (up to hundreds of J/cm3^3 reported for natural events); he concluded that the laboratory-analog claim is unsubstantiated. Shabanov's reply invoked corona-discharge physics and much smaller directly measured charges (about 2×10−62\times10^{-6} C), leaving the discrepancy unresolved in print. An exchange in the Journal of Atmospheric and Solar-Terrestrial Physics (2023-2025, opening with the online publication of the Shmatov-Stephan critique in December 2022) continued the dispute without consensus. Meanwhile, mechanistic hypotheses for natural ball lightning continue to proliferate without convergence.

Problem Statement

Establish the physical mechanism that produces and sustains the long-lived luminous objects (plasmoids) of the Gatchina discharge, and decide on that basis whether they are genuine laboratory analogs of natural ball lightning. The account must be quantitative, consistent with the published measurements, and testable by decisive noncontact diagnostics, and must address: (i) formation - how the discharge phases (plasma sheet over the electrolyte, jet, detachment) and the underlying streamer/leader microphysics create a detached object; (ii) structure - the magnitude, sign, and spatial distribution of the uncompensated charge and of the insulating envelope (including whether the charge resides in a thin shell with only short-range (non-crystalline) molecular order, as conjectured), together with the internal composition, aerosol content, and temperature, and the plasma-chemical kinetics that synthesize the envelope material from air and water; (iii) stability and decay - what balances the electrostatic, thermal, and mechanical (including vortex-flow) pressures over the autonomous lifetime of roughly 0.1-1 s, what sets that lifetime, and how the conductor-selective energy release (local melting of conductors without heating embedded low-melting dielectrics) operates; and (iv) the boundaries of the existence regimes in the facility parameter space (charging voltage, capacitance, commutation time, electrode material and geometry, water conductivity, additives, ambient composition), including the interpolation between the two observed extreme modes (high-charge, low-temperature envelope-stabilized objects versus low-charge, thermally inflated short-lived ones). The account must be quantitative enough to discriminate the specifically contested claims and must name the decisive noncontact measurement (observable and expected signal) that would settle each: the magnitude of the uncompensated charge (about 2×10−62\times10^{-6} C measured versus 4×10−44\times10^{-4} C from the electrostatic model), the energy budget of the objects, and whether their properties match the observational statistics of natural ball lightning (lifetime, energy density, and the characteristic behaviors) - i.e., whether the ball-lightning analogy is physically justified or only visual.

References

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