Ball Lightning(61)
In this photo, we seemed to be looking at a still water surface. A small, invisible stone had landed on the surface, kicking up a bubble, which fractured, sending liquid particles in all directions as waves spread out in rings on the surface....
“This is a high-energy laser striking a metal surface.”
Lin Yun asked inquisitively, “Then what can you film with a hundred million frames per second ultra-high-speed camera?”
“Those images are classified, so I can’t show them to you. But I can tell you that the cameras often record the controlled nuclear fusion process in a tokamak accelerator.”
*
High-speed imaging of thunderball energy release progressed quickly. Macro-electrons were passed through all ten lightning stages and were excited to very high energy states, with energy levels far higher than any ball lightning ever excited in nature, allowing their energy release process to be somewhat more noticeable. The excited thunderballs entered the target area, which had targets of various shapes and compositions: wooden cubes, plastic cones, metal balls, cardboard boxes filled with shavings, glass cylinders, and so on. They were distributed on the ground or on cement platforms of varying height. Pure white paper was laid out under each, giving the whole target area the feel of an exhibition of modern sculpture. After a thunderball entered the target area, it was slowed by a magnetic damper, so it drifted about until it discharged or went out on its own. Three high-speed cameras were set up on the edges of the target area. They were massive and structurally complicated, and unless you knew what they were, you wouldn’t think they were cameras. Since there was no way of knowing beforehand which target the thunderball’s energy would strike, we had to rely on luck to capture the target.
The test started. Since it was highly dangerous, all of the personnel exited the area. The whole test procedure was directed by remote control from an underground control room three hundred meters from the lab.
The monitor showed the superconducting battery releasing the first bubble, which contacted the first arc. The monitoring system transmitted a distorted rushing sound, but the loud crack carried across the three hundred meters from the lab. The excited ball lightning moved slowly forward under the influence of the magnetic field, passing through nine more arcs as thunder rumbled ceaselessly from the lab. Every time the ball lightning contacted an arc, its energy levels doubled. Its brightness didn’t increase correspondingly, but its colors changed: from dark red, it turned orange, then yellow, then white, bright green, sky blue, and plum, until at last a violet fireball entered the acceleration area, where it was whipped by an acceleration field into a torrent. In the next instant, it entered the target area. Like plunging into still water, it slowed down, and began to drift among the targets. We held our breath and waited. Then, after a burst of energy and a flash of light, a tremendous noise came from the lab that shook the glass cases in the underground control room. The energy release had turned a plastic cone into a small pile of black ash on white paper. But the high-speed camera operators said that the cameras had not been trained on that target, and so nothing had been recorded. Another eight thunderballs were subsequently fired off. Five of them discharged, but none of them struck the targets the cameras were trained on. The last energy release struck a cement platform supporting a target, blowing it to bits and causing an immense mess in the target area, so the experiment had to be halted until the lab, which now smelled heavily of ozone, was set up again.
Once the target area was reset, the tests continued. One macro-electron after another was fired at the target area to play a game of cat and mouse with the three high-speed cameras. The optics engineers worried about the safety of their cameras, since they were the equipment nearest to the target area, but we pressed on. It wasn’t until the eleventh discharge that we captured an image of a target being struck, a wooden cube thirty centimeters on a side. This was a wonderful example of a ball lightning discharge: the wooden cube was incinerated into ash that retained its original cubic form, only to collapse at a touch. When the ash was cleared, the paper beneath it was completely unaffected, with not even a burn mark.
The raw high-speed image footage was being loaded into the computer, since if we were to play it back at normal speed, it would be more than a thousand hours long, of which only twenty seconds would show the target being struck. By the time we had extracted those twenty seconds, it was late at night. Holding our breath and staring at the screen, we pulled back the veil on that mysterious demon.
At a normal twenty-four frames per second, the whole clip lasted twenty-two minutes. At the time of discharge, the thunderball was around 1.5 meters from the target; fortunately, both the thunderball and the target were in frame. For the first ten seconds, the thunderball’s brightness increased dramatically. We waited for the wooden cube to catch fire, but to our surprise, it lost all color and turned transparent, until it appeared only as a vague outline of a cube. When the thunderball had reached maximum brightness, the cube’s outlines had totally vanished. Then the thunderball’s brightness decreased, a process lasting five seconds, during which the position formerly occupied by the cube was completely empty! Then the outlines of the transparent cube began to take shape again, and soon it regained corporeality and color, only gray white—it was now a cube of ash. At this point, the thunderball was entirely extinguished.
Dumb as wooden chickens, we took a few seconds to recover and think of replaying the video. We now went through it frame by frame, and when we reached the point where the wooden cube was a transparent outline, we paused the video.