US1207347A - Method of obtaining ultra-violet rays by spark discharge. - Google Patents

Description

J. VON KOWALSKI-WIERUSZ. METHOD OF OBTAINING ULTRA-VIOLET RAYS BY SPARKDISCHARGE.

APPLICATION FILED APR. 10. I914. LQW $%?O Patented Dem, I916.

1/776 w/7'e f/vm AG.

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METHOD OF OBTAINING ULTRA-VIOLET RAYS BY SPARK DISCHARGE.

, moment.

Specification of Letters Patent.

Patented 10cc. 5, 19110..

Application filed April 10, 1914. Serial No. 831,060.

To all whom'it may concern:

Be it known that I, JosEPH VON KowAL- SKI-WIERUSZ, citizen of Austria-Hungary, residing at Fribourg, Switzerland, have invented certain .new and useful Improvements in Methods of Obtaining Ultra-Violet Rays by Spark Discharge, of which the following is a specification.

For the purpose of obtaining ultra-violet rays for industrial purposes it has been usual to employ as the source of the rays almost exclusively the arc lamp, for example, in the case of Finsen light, the iron arc-lamp, and in other cases the mercury arc-lamp, while the known method of obtaining the rays from the oscillating spark has not usually been employed since the ultra-violet rays so obtained are too costly in proportion to the energy expended in the creation of the sparkgap.

As a series of scientific investigations have shown, distinction must be made between three different zones of ultra-violet rays, corresponding to the effects which the rays produce. The first zone, or the initial ultraviolet, extends from the visible spectrum to about a wave-length of 3000 Angstrom units. The radiation which corresponds to the rays of this zone is abundantly emitted by the sun. It is but slightly absorbed by the atmosphere. The photo-chemical reactions which this radiation produces are exothermic almost without exception. The physiological and biological properties are similar to those of the adjacent blue and violet radiation, but more intense. This radiation exerts almost no destructive action on the lower forms of life, such as bacteria. The second zone comprises the so-called middle ultra-violet; and extends from about 3000 A to 2000 A. Only the first part of this zone is found in sunlight. The rays of this zone are strongly absorbed by many substances, and therefore the photochemical effects of this radiation are very intense. There is known a whole series of endothermic chemical reactions which are produced at the expense of this radiation. Biologically they are bactericidal and coagulate albumin. Finally, the third zone, the extreme the commercial production of the middle ultra-violet rays and the object of the invention is to enable such ultra-violet rays to be economically obtained in the spark gap.

These radiations between 2800 and 2200 A are preminently effective for sterilization purposes for the following reasons: The investigations of M. Henry have shown that the shorter the wave-length, the more intense is the bactericidal action of the radiations and other investigations have shown that the calcium ion strongly absorbs the short wave-lengths. In consequence of this, rays of less than 2200 A are not to be considered in the sterilization of drinking water, which contains more orless calcium.

According to the present invention the method consists in employing a considerable dampingof the spark gap, as high a current amplitude as possible and a wave length of less than 3000 meters for the oscillation creating the sparks. These conditions may be fulfilled by the usual scientific means at disposal.

The drawing is a diagramof a conventional apparatus for carrying out the method. In the drawing the source of current is represented by alternating current mains feeding into a primary circuit containing the usual Wattmeter, adjustable inductance and resistance. There is also placed in this circuit the primary of a resonance transformer whose secondary is connected in the oscillation circuit which contains the arcs and condensation battery. The electrical constants of the oscillation circuit are preferably such that its period corresponds to a wave length less than 3000 meters.

The desired damping is obtained, for example, by the use of a suitable material for the electrodes which moreover also energetically emits in this sphere ultra-violet rays. Such material may for example be nickel, cobalt and alloys of these two metals with other metals and especially with the metals of the rare earths. Moreover zirconium, tungsten and molybdenum may be employed when the discharge takes place in an inert gas. such as hydrogen or nitrogen. But any other agent increasing the spark decrement can be employed for this purpose as, for example, the injection of a gas jet into the spark gap or the like.

The greatest possible current amplitude for a given tension amplitude, dependent on the electrode material, is obtained in the known manner by, suitable selection of the electric constants of the oscillatory circuit in which the spark is formed.

By extensive experiment it has been shown that the number of spectral lights is not only dependent on the capacity and self-induction used but also on all the electrical conditions of the oscillating circuit and, as regards the radiant energy of difl'erent parts of the ultraviolet being influenced in a different manner by suitable conditions of the circuit, a series of tests demonstrated:

l. With the increase of the maximum amplitude of current in the oscillation circuit the zone which corresponds to the maximum of radiant energy is displaced toward the shorter wave-lengths.

2. In spark gaps, in which the so-called spark damping is greater, the wave-length which corresponds to the maximum of radiant energy is shorter than for spark gaps with less damping. This result can be taken as indicating that the maximum radiation of energy is displaced toward short wavelengths if much energy is consumed in the spark gap. a

3. Finally, research has shown that with different electrodes the position of the maximum of radiant energy in the spark was very dependent upon the electrode material and, in particular, is diflerent for an alloy oftwo metals than might be deduced from the investigations with the pure metals.

Therefore in order to obtain a'favorable efficiency of radiation in the middle ultraviolet, as great as possible amplitude of current must first be obtained in the oscillation. This, however, is dependent upon the capacity, as well as the self-induction of the oscillating circuit, so that the capacity must be as great as possible and the self-induction as small as possible. For an industrial installation it is, however,.compulsory, in increasing the capacity, also to increase the self-induction (in consequence of the selfinduction of the condensers themselves, as well as the connecting wires which must be used between the condensers).

In regard to the spark damping, investigations have shown that it is dependent on the spark material. (See Lehrbuch do? Drahtlosen Telegraphic, by J. E. Zonneck 1913). Further I have found that the spark damping is greater with certain alloys, as for example, invar, than with the pure metals. On the other hand, however, it was found that the spark damping alone is not sufficient to produce an appreciable radiation of energy in the middle ultra-violet. Different metals or metallic alloys possess, in this zone, a different specific capability for radiation, which latter is not always parallel with the great damping. Metals and metallic alloys must be used which simultaneously show, under given electrical conditions, great spark damping and great specific capability for radiation for the middle ultra-violet.

The improved method is as hereinbefore noted particularly economical in the production of those ultra-violet rays which lie in the part most eflective for example for sterilizing purposes, that is, for rays of less than 3,000 p. p. wave length.

In the employment of the rays for sterilization, chemical actions or other purposes it is in many cases necessary or at least desirable to prevent the action of the oxidation of the nitrogen which takes place in the spark gap upon the substances to be treated with the rays. In such cases a film is placed between the spark gap and the substances to be treated which is transparent to ultraviolet rays but keeping back the oxids and the like. This may be efiected by arranging a casing of quartz glass around the spark gap.

1. The method of obtaining ultra-violet rays from an oscillatory spark which consists inconsiderably damping the spark, employing a high current amplitude and employing spark oscillations whose wavelength is less than 3000 meters.

2. The method of obtaining ultra-violet rays from an oscillatory spark which consists in considerably damping the spark, employing a high current amplitude by suitable selection of the electric constants of t e oscillatory circuit in which the spark is generated, and employing spark oscillations whose wave-lengthis less than, 3000 meters.

3. The method of obtaining ultra-violet rays from an oscillatory spark which consists in the use of metal electrodes adapted to considerably damp the spark, employing a high current amplitude and employing spark oscillations Whose wave-length is less than 3000 meters.

4. The method of obtaining ultra-violet rays from an oscillatory spark which con sists in the use of electrodes of an alloy adapted to considerably damp the spark, em-

naoaeaa v ploying a high current amplitude and emcuit in which the spark is generate& and 10 ploying spark oscillations whose waveemploying spark oscillations whose wavelength in less than 3000 meters. length is less than 3000 meters.

5. The method of obtaining ultra-violet In testimony whereof ll affix my signature rays from an oscillatory spark which conin presence of two witnesses sists in the use of electrodes adapted to con- PROF. DR. JOSEPH vor KOWALSKI-WIERUSZ. siderably damp the spark, employlng a high Witnesses: current amplitude by suitable selection of Konsns- JUTTSON,

the electric constants of the oscillatory cir- F. SCININGER.

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