Nikola Tesla - Free-Energy Devices

360 INVENTIONS OF NIKOLA TEFL A.known.Given, then, an electrode which can withstand to a veryhigh limit the effect of the bombardment and outward strain, itwould be safe, no matter how much it was forced beyond thatlimit. In an incandescent lamp quitedifferent considerationsapply. There the gas is not at all concerned ;the whole of thework isperformed on the filament ;and the the life of the lampdiminishes so rapidly with the increase of the degree of incandescencethat economical reasons compel us to work it at a lowincandescence. But if an incandescent lamp is operated withcurrents of very high frequency, the action of the gas cannot beneglected, and the rules for the most economical working mustbe considerably modified.In order to bring such a lamp with one or two electrodes to agreat perfection, it is necessary to employ impulses of very highfrequency. The high frequency secures, among others, two chiefadvantages, which have a most important bearing upon theeconomy of the light production. First, the deterioration of theelectrode is reduced by reason of the fact that we employ a greatmany small impacts, instead of a few violent ones, which quicklyshatter the structure ; secondly, the formation of a large photoshereis facilitated.In order to reduce the deterioration of the electrode to theminimum, it is desirable that the vibration be harmonic, for anysuddenness hastens the process of destruction. An electrode lastsmuch longer when kept at incandescence by currents, or impulses,obtained from a high frequency alternator, which rise and fallmore or less harmonically, than by impulses obtained from a disruptivedischarge coil. In the latter case there is no doubt thatmost of the damage is done by the fundamental sudden discharges.One of the elements of loss in such a islamp the bombardmentof the globe. As the potential isvery high, the moleculesare projected with great speed ; they strike the glass, and usually excitea strong phosphorescence. The effect produced is very pretty ,but for economical reasons it would be perhaps preferable to prevent,or at least reduce to a minimum, the bombardment againstthe globe, as in such case it is, as a rule, not the object to excitephosphorescence, and as some loss of energy results from thebombardment. This loss in the bulb is principally dependenton the potential of the impulses and on the electric density onthe surface of the electrode.In employing \ cry high frecjuen-