Answer to Question #4886 Submitted to "Ask the Experts"

In light of the new findings of neutrons, γ rays, and x rays in cloud-to-ground lightning (Dr. Kuzhevsky on neutrons in lightning in Russian Science News; Joe Dwyer at FIT, γ-ray and x-ray research published in the May issue of Scientific American; Dwyer's paper; and Clint Seward of Electron Power Systems explaining the theoretic base of his fusion energy efforts in Ball Lightning Explained as a Stable Plasma Toroid) please tell me if there is something thermonuclear happening in lightning and, if so, what type.

To my knowledge there is not a consensus among the scientific community as to the existence of thermonuclear reactions attributable to lightning during electrical storms. The Moscow paper by Kuzevsky that you mention supports the possibility and ascribes the production of neutrons to nuclear reactions, specifically the nuclear fusion of deuterium nuclei. The process by which such an event might occur is not clear, although we might consider a few. It is certainly true that the high electrostatic potentials, often millions of volts, developed during such storms are, at least in theory, capable of accelerating deuterium ions to energies sufficient to induce fusion upon collision with other deuterium nuclei, the energy required for fusion being about 100,000 electron volts.

One major obstacle to such a pathway to fusion is that the atmosphere is full of atoms and molecules that would interfere by causing collision energy losses by the deuterons before they gained sufficient energy and encountered a nucleus suitable for fusion. This is why, aside from the electrical breakdown of the gas, when accelerators are used to induce fusion by bombarding targets with deuterons, the acceleration takes place under high-vacuum conditions. During a lightning storm, in addition to cloud-to-earth discharges, many other electrical discharges occur within a given cloud and between clouds; some discharges have even been observed to occur in the upward direction in which large numbers of electrons appear to stream out of the ionosphere. Astronauts and others have reported luminous discharges at high elevations in the stratosphere. It might be possible that greater acceleration of ions could occur in the rarefied atmosphere at high altitudes, and this might favor high-energy reactions.

As described in the cited article by Seward, the phenomenon of "ball" lightning is explainable as a spinning and rotating toroidal-shaped gas plasma. For such a shape to be sustained, high currents must flow within the torus so as to produce a magnetic field sufficient to confine the plasma. It is conceivable, but unproven, that such a field might be sufficient to compress plasma nuclei sufficiently to cause fusion (the same principle used in earth-bound fusion experiments using plasmas and external magnetic confinement).

We might note that if the temperature of the plasma associated with a lightning discharge were sufficiently high, the thermal kinetic energies of ions might be adequate to overcome the coulombic barrier between these nuclei. Reported temperatures in the discharge column of a lightning bolt approach 30,000 Kelvin, much less than the temperature associated with the above-noted 100 keV energy needed for fusion, that temperature being about one billion Kelvin.

There may exist other possibilities for lightning-induced nuclear reactions. For example, there are tremendous numbers of electrons produced during the discharge process. If some of these could achieve megavoltage potentials they could interact in the vicinity of atomic nuclei and produce high-energy bremsstrahlung radiation. Conceivably, such radiation could interact with other nuclei through photoneutron reactions in which the high-energy photons provide enough energy to the nuclei to set free neutrons.

At this stage, the bottom line is that we don't have sufficient evidence as to how or even if nuclear fusion processes are associated with lightning discharges in the atmosphere. It is interesting to note that, exclusive of nuclear processes, there is still much that is unknown regarding many aspects of atmospheric electrical discharges, despite the large extent and duration of study that has been aimed at this area. The process of nuclear fusion and other possible nuclear reactions attendant to such discharges has been added to the list of unanswered questions; it will be interesting to see what develops.

George Chabot, PhD, CHP