Condign volumes 1 to 3

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# UNCLASSIFIED

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sizes reported, $ \lambda $ would have to be 35-100cm. Hence, the upper limit would be $ 3 \times1 0^{8} / 1=3 0 0 \mathrm{M H z} $ (whereas 30 and 50MHz are reported from microcharges). It should be noted that rarely are there any measurements from real ball lightning; any measurements quoted are from experiments attempting to simulate the phenomenon.

## LABORATORY-PRODUCED BALL LIGHTNING

31. Many attempts have been made to produce ball lightning under laboratory conditions and it is reported $ ^{1} $ that (in the USA) it is routinely possible to produce a specific type of this phenomenon. Golka also claims that plasmoids can be produced by combustion inside a 'microwave oven'. However, it is not proposed that the ball lightning generated accounts for all types. In the experiments the fireballs lasted from two to five seconds but with only diameters of $ \sim1 $ cm. This has been achieved by short-circuiting 60Hz currents as low as 1200A across copper and aluminium electrodes under $ \sim2 $ cm of water. Another researcher (Silberg, unreferenced) describes how this phenomenon, produced green fireballs in a submarine engine room, using 260 Volts and 156,000 Amperes. Ball diameter was 6 to 10cm. For a 10cm diameter ball (volume $ 515\mathrm{cm}^{3} $ ）there are $ 1.4\mathrm{X}10^{23} $ molecules. When the medium (used in the switching contacts) is nitrogen and an ionisation energy of 15eV per ion pair for the single ionisation, it can be calculated that there must be $ 3.4\mathrm{X}10^{4} $ Joules contained in the ball. The ball quickly disperses unless a source of replenishment energy is present.

32. The fireballs produced rise to the surface and remain until exhausted, 1-2KJ of energy having been deposited. The type of lightning balls produced are reported to be similar to those observed in aircraft during flight and, strangely, in submarines during WWII. With higher power the 'ball' can be made to travel higher from the surface and 'bounce' and 'dance'. It is postulated that the

more power applied, the larger the diameter which may be produced. Hence, the phenomenon might be scaleable.

33. Other characteristics clearly depend on the materials and size of the electrodes and their burning temperature when a tremendous energy level is applied to a very small surface area. For aluminium this is of the order $ 4 4 0 0^{\circ} \mathrm{F} $ . As might be expected, as the fireballs surface they sizzle and hiss, some leave the surface and produce spiralling smoke trails, leading to the supposition that the fireballs are spinning (see below). Different electrode types produce more or less smoke. Those remaining on the water exhibit random motion until they decay.

34. Experiments were only made with the electrodes under water because this method enabled measurements to be made before the fireballs darted off in all directions, making measurements difficult. Whereas previous researchers had expected high voltages to be a prime requirement, these experiments were made at 40-50 volts. Even so, enough energy overall was deposited on occasions to make the balls leave the surface of the experimental tank and leap onto the floor.

35. Aluminium electrodes produce white fireballs, while iron-to-iron electrodes produce yellow. Either the outer surface or the kernel appears to be spinning. As soon as the ball stops emitting light, it shrinks to sugar-grain size. If over water these particles sink.

36. It is postulated that if the sphere is spinning a boundary layer phenomena will be set up, retarding thermal radiation in the same way that the filament of an incandescent lamp forms sheath layers which keep the filament at a higher temperature.

37. As a result of these experiments the author suggests that, as ball lightning has only very rarely been reported inside pressurised aircraft, that the product of the balls was due to natural lightning attachment to the aircraft skin forming a small hole (at $ 4 4 0 0^{\circ} \mathrm{F} $ ) with consequent formation of a plasma ball on the inside of the aircraft.