US2121882A - Electrode - Google Patents

Description

June 28, 1938. B. O'BRIEN 2,121,882

ELECTRODE I Filed April 18, 1934 3 Sheets-Sheet 3 I I I I I ITI I I l I I I I ITI 'I I I IIIIITIIIIIIIIITIIIIlIIIITIIIIIIIIIUIIIlIIIITIIIIIIIImmlIIIMIIIIIIIHIIIIIIIIEIIIIIIWIIIIIIIII'fiIIIIlIIffiIIIIIIIBIIIIIIIii II I I I T: I I l I I I! I'I'IIIIIIIII'I'IIIIIIIIITIIIIIIIIITIIIIIIIIITII IIIIIITIIIIIIIII'fiIIIIIIIIfiIIIIIIIflIIIIIIIIIf IIIIIIIIIIIIIIIIIIFIIIIIIIIIFIIIIIIIM l I I l I ITI l I I I I l ITI I I I IIIII'I'IIIIIIIIITIIIIIIIIITIIIIIIIIITIIIIlIIII'fiIIIIIIImIIIIIIImIIIIIIIiTIIIIWIIIIIIIIIIIIIIIIIIffiIIIIIIIffiI I I l IT I I l I I I ITI I I I I l I l ITIIIIlIIIITIIIIIIIIITII IIIIIITIIIIIIIInuIIIIIIfiIIIIIIIMIIIIIIIIHIIIIIIIMIIIIIIWII |IIIIIfiIIIIIIIIfiIIIIIIIIfiIIIIIIIIfiII l IT I I l I I I I I ITI I I I I I IIITIIIII IIITIIIIIIIIITIIIIIII|ITIIIIIIIIHIIIIIIIIMIIIIIIIflIIIIIIIIflTIIIIIIIW |I[IlI|lTllilllllmlllllllmllllllli I INVEZVTOR EZaIo 015 70370 BY & %z Is A TTORNE Ys Patented June 28,1938

PATENT OFFICE ELECTRODE Y Brian O'Brien, Rochester, N. Y. Application April is, 1934, Serial No. 121,221

I 2 Claims. 'This invention relates to electrodes for use with electric currentsto produce either arcsvor intermittent sparks.

An object of the invention is the provision of an improved electrode which will produce an are or spark particularly valuable and suitable for the production of predetermined effects on a living body or on non-living systems, such as milk or other foods.

Another object of the invention is the provision of such an electrode which will form a source of light of relatively high intensity in the ultra-violet region of the spectrum, in the wave length range of 2750 A to 3100 A, and which will have relatively low. intensity in wave lengths be-' low about 2700 A.

A further object is the provision ofan improved electrode especially suitable for use in treating food or the human skin to impart desirable characteristics thereto without injuring or changing the taste of or imparting other undesirable characteristics to the treated food, and without irritating the human skin.

To these and other ends the invention resides in certain improvements and combinations of parts, all as will be hereinafter-more fully described, the novel features being pointed out in the claims at the end of the specification.

In the drawings:

Fig. 1 is a diagram illustrating the spectral energy distribution of an are formed with an electrode constructed in accordance with the I preferred embodiment of the present invention, the'intensity of emission being shown with relation to wave length expressed in Angstrom units;

Fig. 2 is a diagram similar to Fig. 1, but plotted on'a semi-logarithmic scale in which the ordinates represent logarithms to the base III of intensity, while the abscissas represent, as before, wave length in Angstrom units;

Fig. 3 is a spectrogram of an arc formedby an electrode of carbonwith which is incorporated,

magnesium, vanadium, and chromium;

Fig. 4 is a similar spectrogram of anelectrode of plain carbon with its ordinary commercial impurities;

Fig. 5 is a similar spectrogram of an electrode composed of such carbon plus magnesium;

Fig. 6 is a similar-spectrogram'of an electrode of carbon plus vanadium;

Fig. 7 is a similar spectrogram of carbon plus chromium; v v v Fig. 8 is a similar spectrogram of carbon plus manganese Fig. 9 is a similar spectrogram of carbon plus arsenic;

Fig. 10 is a similar spectrogram of carbon plus zirconium;

Fig. 11 is a similar spectrogram of carbon plus 5 thorium; and

emissions of relativelyhigh intensity in the 15 ultra-violet region of the spectrum, in the wave length range of about 2750 angstrom units to about 3100 A, and at the same time to avoid the highly destructive or irritating action of wave lengths below about 2700 A or 2750 A. While such shorter wave lengths may be removed by the use of light filters, yet the use of filters is frequently inefilcient and troublesome, so that his preferredto employ a light source in which the emissions at wave lengths below about 2700 A are of relatively lowintensity.

According to the present invention, it is possi ble to produce a'high intensity of radiation in the desirable region from 2750 Ato 3100 A by the use of an arc in which the electrode is made of or has-incorporated in it (by coring or otherwise) the metal magnesium or compounds of magnesium, together with one or more other elements emitting spectrum lines which at least partially fill inthe gaps between the brighter lines of the magnesium spectrum lying in the wave length range of 2750 A to 3100 A, and which added element or elements at the same time donot seriously increase the intensity of radiation at wave lengths shorter than about 2700 A or 2750 A.

40 Within the above mentioned desirable range of 2750 A te 3100 A, there are severalv important lines in the magnesium spectrum. In the case of thearc spectrum, the more intense lines of -magnesium in this region are at wave lengths 2796 A, 2803 A, 2852 A, 3091 A, 3093 A, and 3097 A. In addition, there are a number of other ma nesiumlines ofmoderate. intensity within this spectrum range, but the lines specifically listed above greatly exceed in intensity the rest of the 5 a magnesium lines in the above spectral range, so

that there are important gaps left in the spectrum between these lines of relatively great iiitensity, which it is desirable to fill.

In the case of a spark between-electrodes containing magnesium or its compounds, the same lines above mentioned appear, but in greatly reduced intensity, except the lines at 2796 A and 2803 A, both of which are of much greater relative intensity in the case of the spark than in the arc. In the spark the lines at 2791 A, 2798 A, 2929 A, 2937 A, and 3105 A become of appreciable intensity in addition to the intense lines at 2796 A and 2803 A above mentioned, but there still remain substantial gaps between these lines.

A number of elements have been found with spectral emissions which tend to fill these gaps without seriously increasing the intensity of emission at wave lengths less than about 2700 A or 2750 A. Such elements are vanadium, chromium, manganese, arsenic, zirconium, thorium and uranium. These elements just named, together with magnesium, may be considered as a class, group or genus, the classification being based on their physical property of producing spectral emission of relatively high intensity in the wave length range of about 2750 A to 3100 A, without producing intense emissions at wave lengths below about 2700 A. Furthermore, the elements magnesium, vanadium, chromium, manganese, and arsenic may be considered as a sub-group of the main group above mentioned, since the elements forming this sub-group are found in practice to give comparatively greater intensity of spectral emission in the above mentioned desirable range without corresponding undesirable short wave emission. The remaining elements zirconium, thorium and uranium of the main group are less desirable in this respect.

, Vanadium and chromium are particularly suitable for use according to the present invention,

and either or both of them may be used without magnesium, with or without one or mre of the other elements of the main group or genus above mentioned, in special cases where it is desirable to exclude magnesium. Ordinarily, however, it is 7 preferred to employ magnesium together with one or more of the other elements of the group.

For direct current arcs, and for sparking ap'- paratus (that is, apparatus to produce intermittent sparks) for use with either direct current or alternating current, the electrode may be-made entirely or substantially entirely of elements of the above mentioned main groupfltogether with any necessary binder. For use with alternating current arcs, however, it is preferred to include a substantial quantity of carbon in the electrode,

and conveniently the electrode may be in the form of a tubular body of carbon with a core of ma terial including two or more of the elements of the above mentioned group.

A particularly satisfactory electrode, which forms the preferred embodiment ofthe invention 7 under many circumstances, is one in which magnesium, vanadium, and chromium are all employed. These materials give excellent results when used in the proportions of 100 parts of magnesium, 20 parts of vanadium, and 3 parts of chromium, mixed if desired with a quantity of soft carbon such as soft lamp black and with a suitable binder such as gum tragacanth, sodium silicate solution, or both. Such a mixture can be used either as .the core for a carbon electrode (or otherwise combined with the carbon) or as a complete non-carbonaceous electrode. When used with carbon, the non-carbonaceous mate,- rials should ordinarily constitue from three per centum to twenty per centum of the entire electrode, the optimum being approximately ten per centumin most cases. A cored carbon electrode,

are formed by a cored carbon electrode of the above mentioned preferred composition. In Fig; 2, the same emissions are plotted on a scale in which the ordinates, instead of representing the intensities themselves, represent logarithms to the base II) of the intensities, with the advantage that relative intensities of emissions (as distinguished from absolute intensities) are correctly represented irrespective of where the zero point of the logarithmic scale be placed or whether its location be changed, and with the further ad vantage that this logarithmic graph can be compared more easily with the spectrogram reproductions in Figs. 3 to 12, since these spectrograms are also on a logarithmic scale of intensities. From these two diagrams, it can be readily seen that the intensity of emissions in the range of about 2750 A to 3100 A is materially greater than the intensity below about 2700 A.

A reproduction of an actual spectrogram of an arc formed by an electrode of this preferred form is illustrated in Fig. 3 of the drawings, the horizontal scale reading directly in hundreds of angstrom units. It will be seen from this spectrogram that such an are also has relatively high emission at wave lengths above about 3100 A, but such wave lengths above about 3100 A may be disregarded because, so far as known at present, emissions in these upper wave lengths are neither beneficial nor detrimental.

The spectrograms of Figs. 3 to 12, inclusive, are special spectrograms made with a quartz spectrograph equipped with a rotating logarithmic spiral aperture sector disk and a projected intensity scale, and the height of each vertical line of the spectrogram is in proportion to the logarithm of the photographic intensity of emission at that wave length. a

While the above mentioned elements and proportions are preferred, it is to be understood that both the proportions and the elements em-v ployed in the electrode can be considerably varied wave length range from 2750 A to 3100 A, but

these elements also produce more or less emissions in wave length below 2700 A and this must be taken into account when selecting the elements to be used and determining the proportions in which they are to be used.

Fig. 4 is a spectrogram, of the same special type shown in Fig. 3, showing emissions from an electrode of plain carbon in its ordinary commercial form with commercial impurities. Fig. 5

is a similar spectrogram of such an electrode to l which magnesium has been added, and Figs. 6 to 12, inclusive, are similar spectrograms of carbon electrodes to which have been added, re-

spectively vanadium, chromium, manganese, ar-

. senic, zirconium, thorium, and uranium. [Thus these spectrograms of Figs. to 12, inclusive, show the characteristics of each of the elements of the main group or class above mentioned,

' and, with this information at hand, those skilled in the art can readily combine the various desired elements in proper proportions to produce the desirable result of high intensity of emission in the range of about 2750 A to 3100 A,, and relatively low intensity of emission below. about 2700 A. As willbe seen from the spectrograms, magnesium, vanadium, and chromium have the most desirable characteristics from the standpoint of this invention, and the other elements of the class have decreasingly desirable characteristics approximately in the order in which they have been named.

From the various characteristics of the-various elements of the group or class, it is apparent that all of these elements could not be used in the same proportions. For example, the propor-" tion of vanadium could be increased somewhat or reduced to about one quarter of the proportion indicated as the preferred construction,

' without undesirable effects, and the chromium could be reduced or increased several fold in proportion to the other components without undesirable effects. But if manganese or arsenic were substituted for the chromium or vanadium,

they would have to be used-generally in lesser.

amounts than the vanadium in order that appreciable emission at wave lengths less than 2700 A may be avoided. This is in part due to the.- influence which one element may exert upon the emission of energy by another element si-v about 2750 A to 3100 A is tobe secured in propor I tion to the emission of wave lengths less than about 2700 A.

When speaking of the various elements which may be used in the electrode, it is to be understood that the elements may be employed either inithe metallic state or in the form ofany suit-' able compound.

As mentioned above, sodium silicate may be used as a binder for the other components of the electrode. While this material has certain desirable characteristics, it is also found to have certain characteristics which are undesirable from the standpoint of the present invention, so that sodium silicate should be used as sparingly as possible; Furthermore, it is seen from the explanation given below that other materials are found to possess the same desirablev characteristics as sodiumsilicate without having its undesirable characteristics, and such other materials may be used, according to the present invention, to replace sodium silicate wholly or in part.

- It has been known for some time that sodium and potassium silicates have a'beneflcial effect in causing alternating current arcs and other carbon arcs to burn more smoothly, and for this reason,vthese silicates have been called "arc sus-e taining materials, but the reason for this action does not appear to have been understood. This -arc sustaining eizect of sodium and potassium silicates is a desi able characteristic from the standpoint of the present invention.

But an important undesirable characteristic, from the standpoint of the present invention, is that the spectral emissions of silicon are highly objectionable if present in any appreciable amount, for silicon emits considerable intensity in the neighborhood of wave length 2500 A.

It is now found that it is not the silicon in sodium silicate or potassium silicate that gives these materials, their are sustaining, character, but rather the alkali therein which produces this result. Sodium and the other alkalies have a relatively low ionization potential. Because of this low ionization potential, the Saha thermal ionization as well as the ionization due to bombardment in the arc stream is high. Moreover, at and near the zero point of the current wave in an alternating current arc, a considerable number of the alkali atoms in the arc stream re main ionized,-and thus they may greatly aid the arc in reestablishing itself as the alternatingcurrent reverses in direction from the previous half cycle. In addition to alow ionization potential, the alkalis and some of theircompounds have a low thermionic or Richardson work function. Thus in those cases where their boiling points are suiiiciently high so that they or their compounds 'cover'part of the active electrode surface, their high thermionic emission also assists in the reestablishment of the arc when the current re-' verses. This latter property is possessed also by many metals other than the alkalis, including, for

example, vanadium and chromium..

Thus it followsthat from the electrical arc sustaining standpoint, it is the presence of alkalies rather than of silicon, that is desirable as assisting in proper functioning of the arc., But from'an optical standpoint the presence of two much alkali tends to suppress the spectrum lines of other elements, becausev the alkali ions carry an unduly large proportion of the current in the are stream, thus reducing the ionization of other elements. In this way, some of the emission lines of carbon itself and of carbon compounds may also be partially suppressed. In some cases, this suppression is desirable as, for example, sodium or potassium may be useful in partially suppressing the silicon lines in the neighborhood of wave length 2500 A, but unless caution is exercised, some of the desirable spectrum lines of other elements may also be partially suppressed. It should also be pointed out that, in contrast with the suppressing characteristics of alkalls in the 1 arc stream, high thermionic emission does not, in general, ap reciably enact the spectrum energies either of 'e elements causing the thermionic emission or of other elements which may be pres- This isbecause thermionic emission is from solid or liquid substances on the electrodes and v not in'the'arc stream, andhence from atoms which are not, at that time, emitting spectrum lines. thermionic emission is not detrimental from an optical standpoint, although the use of a readily ing to suppress some of the desirable lines. of

.spectral emission. Moreover, it is found that when alkali is added in increasing quantities, the arc sustaining" properties appear'before there is enough alkali present to cause any serious suppression of desirable wave. lengths from other ele- Thus the use of an electrode having high ionizable vapor substance in the are stream it- I self may be detrimental as suppressing or tendments. Hence a relatively small quantity of alkali is not particularly harmful from the optical standpoint, but is beneficial from the electrical arc sustaining standpoint, and can be used to advantage.

From the above explanation it is seen that silicon is undesirable for the purposes of the present invention and should be used sparingly if at all; and that the desirable arc sustaining properties may be secured by using alkalis (preferably in relatively small amounts, to avoid undesirable suppression characteristics) or other materials having high thermionic emission. Alkali compounds such as the carbonates are useful, as they aid in sustaining the arc while avoiding the undesirable characteristics of the silicates.

. Instead of an alkali metal, an alkaline earth such as magnesium may be used as an aid in sustaining the are. But in the case of an alkaline earth, a much' larger quantity is usually necessary, to produce the same result, than in the case of an alkali metal. The addition of a large amount is not objectionable in the case of magnesium, however, because magnesium is one of materials of the group or class already named as having desirable spectral characteristics for the purposes of this invention.

The alkaline earths are also valuable because their oxides (such as magnesium oxide, whichforms rapidly under working conditions whenever magnesium is present) have high boiling emission; and that when using such other alkaline materials, they should (with the exception of magnesium and its compounds) be used in small quantities, so as to provide the desirable arc sustaining characteristics without producing serious of these materials not only are in the class or group of elements having the, desired spectral emissions, but also are materials having desirable arc sustaining characteristics.

An electrode made in the preferred form above disclosed gives a good light which closely simulates the appearance of natural sunshine, and which is cheerful for sick patients. It is also of commercial value in the irradiation of various products, such as' milk, and the color value of the light is such that it enhances the appearance of the products being irradiated. For example, milk undergoing irradiation from such light has its natural rich and-creamy appearance fully maintained or even heightened, in contrast to the bluish or skimmed-milk appearance given even to rich creamy milk during irradiation by certain other forms of lights.

I claim:

1. A carbon electrode having a core made of a mixture consisting substantially of magnesium, vanadium, and chromium, in which there are at least five parts of vanadium to each part of chromium, and at least five parts of magnesium to each part of vanadium.

2. A carbon electrode having a core made of a mixture consisting substantially of magnesium, vanadium, and chromium, in the proportions of approximately one hundred parts of magnesium, twenty parts of vanadium, and three parts of chromium.

BRIAN OBRIEN.

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