SHOCKWAVES

James Clark-Maxwell predicted the possibility that electromagnetic waves might exist. In theoretical discussions designed to more thoroughly explain his mathematical descriptions, Maxwell asked his retiders to consider two different kinds of electrical disturbance possibly existing in Nature. The first consideration dealt with longitudinal electric waves, a phenomenon which required alternating concentrations of electrostatic field lines. This densified and rarefied pulsation of electrostatic fields necessarily demanded a unidirectional field, one whose vector was fixed in a singular direction. The only variable permitted in generating longitudinal waves was the concentration of he field. Subsequent propagation along the electrostatic field lines would produce pulsating thrusts on charges, pulsations moving in a single direction. These “electrical soundwaves” were rejected by Maxwell, who concluded that such a condition was impossible to achieve.

His second consideration dealt with the existence of transverse electromagnetic waves. These required the rapid alternation of electrical fields along a fixed axis. Space spreading electrical lines would supposedly “bend to and fro” under their own momentum, while radiating away at the speed of light from the alternating source. Corresponding forces, exact duplicates of the alternations produced at the source, would be detected at great distances. He encouraged that experimenters seek this waveform, suggesting possible means for achieving the objective. And so the quest to find electromagnetic waves began.

In 1887, Heinrich Hertz announced that he had discovered electromagnetic waves, an achievement at that time of no small import. In 1889, Nikola Tesla attempted the reproduction of these Hertzian experiments. Conducted with absolute exactness in his elegant South Fifth Avenue Laboratory, Tesla found himself incapable of producing the reported effects. No means however applied would produce the effects which Hertz claimed. Tesla began experimenting with abrupt and powerful electric discharges, using oil filled mica capacitors charged to very high potentials. He found it possible to explode thin wires with these abrupt discharges. Dimly perceiving something of importance in this experimental series, Tesla abandoned this experimental series, all the while pondering the mystery and suspecting that Hertz had somehow mistakenly associated electrostatic inductions or electrified shockwaves in air for true electromagnetic waves. In fact, Tesla visited Hertz and personally proved these refined observations to Hertz who, being convinced that Tesla was correct, was about to withdraw his thesis. Hertz was truly disappointed, and Tesla greatly regretted having to go to such lengths with an esteemed academician in order to prove a point.

But while endeavoring toward his own means for identifying electrical waves, Tesla was blessed with an accidental observation which forever changed the course of his experimental investigations. Indeed, it was an accident which forever changed the course of his life and destiny. In his own attempts to achieve where he felt Hertz had failed, Tesla developed a powerful method by which he hoped to generate and detect real electromagnetic waves. Part of this apparatus required the implementation of a very powerful capacitor bank. This capacitor “battery” was charged to very high voltages, and subsequendy discharged through short copper bus-bars. The explosive bursts thus obtained produced several coincident phenomena which deeply impressed Tesla, far exceeding the power of any electrical display he had ever seen. These proved to hold an essential secret which he was determined to uncover.

The abrupt sparks, which he termed “disruptive discharges”, were found capable of exploding wires into vapor. They propelled very sharp shockwaves, which struck him with great force across the whole front of his body. Of this surprising physical effect, Tesla was exceedingly intrigued. Rather like gunshots of extraordinary power than electrical sparks, Tesla was completely absorbed in this new study. EJectrical impulses produced effects commonly associated only with lighming. The explosive effects reminded him of similar occurrences observed with high voltage DC generators. A familiar experience among workers and engineers, the simple closing of a switch on a high voltage dynamo often brought a stinging shock, the assumed result of residual static charging.

This hazardous condition only occurred with the sudden application of high voltage DC. This crown of deadly static charge stood straight out of highly electrified conductors, often seeking ground paths which included workmen and switchboard operators. In long cables, this instantaneous charge effect produced a hedge of bluish needles, pointing straight away from the line into the surrounding space. The hazardous condition appeared briefly, at the very instant of switch closure. The bluish sparking crown vanished a few milliseconds later, along with the life of any unfortunate who happened to have been so “struck". After the brief effect passed, systems behaved as designed. Such phenomena vanished as charges slowly saturated the lines and systems. After this brief surge, currents flowed smoothly and evenly as designed.

The effect was a nuisance in small systems. But in large regional power systems where voltages were excessive, it proved deadly. Men were killed by the effect, which spread its deadly electrostatic crown of sparks throughout component systems. Though generators were rated at a few thousand volts, such mysterious surges represented hundreds of thousands, even millions of volts. The problem was eliminated through the use of highly insulated, heavily grounded relay switches. Former engineering studies considered only those features of power systems which accommodated the steady state supply and consumption of power. It seemed as though large systems required both surge and normal operative design considerations. Accommodating the dangerous initial “supercharge" was a new feature. This engineering study became the prime focus of p>ower companies for years afterward, safety devices and surge protectors being the subject of a great many patents and texts.

Tesla knew that the strange supercharging effect was only observed at the very instant in which dynamos were applied to wire lines, just as in his explosive capacitor discharges. Though the two instances were completely different, they both produced the very same effects. The instantaneous surge supplied by dynamos briefly appeared super-concentrated in long lines. Tesla calculated that this electrostatic concentration was several orders in magnitude greater than any voltage which the dynamo could supply. The actual supply was somehow being amplified or transformed. But how?

The general consensus among engineers was that this was an electrostatic “choking" effect. Many concluded it to be a “bunching" action, where powerfully applied force was unable to move charge quickly through a system. Mysterious, the combined resistance of such systems seemed to influence the charge carriers before they were able to move away from the dynamo terminals! Like slapping water with a rapid hand, the surface seemed solid. So also it was with the electrical force, charges meeting up against a seemingly solid wall. But the effect lasted only as long as the impact. Until current carriers had actually “caught up" with the applied electrical field, the charges sprang from the line in all directions. A brief supercharging effect could be expected until charges were distributed, smoothly flowing through the whole line and system. The dynamo itself thus became the brief scene of a minor shockwave. He began wondering why it was possible for electrostatic fields to move more quickly than the actual charges themselves, a perplexing mystery. Vas the field itself an entity which simply drove the more massive charges along? If this was true, then of what was the electrostatic field itself “composed”? Was it a field of smaller particles? The questions were wonderfully endless.

Despite the wonderful ideas which this study stimulated, Tesla saw a practical application which had never occurred to him. Consideration of the dynamo supercharging effect suggested a new experimental apparatus. It was one v'hich could gready outperform his capacitor battery in the search to find electrical waves. A simple high voltage DC generator provided his electric field source. Tesla understood that the resistance of lines or components, viewed fi"om the dynamo end, seemed to be an impossible “barrier” for charge carriers to penetrate. This barrier caused the “bunching” effect. Electrostatic charges were literally stopped and held for an instant by line resistance, a barrier which only existed during the brief millisecond interval in which the power switch was closed. The sudden force application against this virtual barrier squeezed charge into a density impossible to obtain with ordinary capacitors. It was the brief application of power, the impact of charge against the resistance barrier, which brought this abnormal electro-densified condition. This is why the conductive wires in his present experiment often exploded.

The analogy to steam power and steam engines was unmistakable. Large steam engines had to be valved very carefiolly. This required the expertise of old and well-experienced operators who knew how to “open up” an engine without rupturing the vessels and causing a deadly explosion. Too suddenly valved, and even a large steam engine of very high capacity could explode. Steam also had to be admitted into a system gently, imtil it began smoothly and gradually flowing into every orifice, conduit, and component Here too was the mysterious “choking” effect, where a large capacity system seemed to behave like an uncommonly high resistance to any sudden and sustained application of force. Tesla learned that he could literally shape the resultant discharge, by modifying certain circuit parameters. Time, force, and resistance were variables necessary to producing the phenomenon.