US1598848A - Radiofrequency arc converter and method of operating same - Google Patents

Description

.septn 7, 192e.

C. C. CHAPMAN RADIO FREQUENCY ARC` CONVERTER AND METHOD 0F OPERATING SAME /NVe/vroz Corwin CTC/Mpman iled March 24. 1923 FIEJ.

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Patented Sept. 7, 1926.

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oonwIN c. CHAPMAN, "or rane amie, cnnrsoanm, nssienoza, Bv Mnsnn Assen! Ivi-serre, 'ro 'nanna-AL TnLnGnArI-I courant@ *oir enn'nANcIsoo, CALIFORNIA', A

'coneau-mman or CALIFORNIA.

` -RADIOF'REQ'ENCY AEC CONVERTER "Ann Mn'rnon or ernaar-Ine Application 'filed 'Mar-ch 24, 3.923. lSerial No. 627,477;

' This invention relates to an are rconverter ltor producing` radio frequency oscilla- "rions,v and more 4partic'ular'ly to such `a oonverter vin Which the arc is maintained in 'an c air-tight chainber containijng'a hydrocarbon atmosphere. Y

It 4is well lknown that aro converters ot this type lrequire/an atinos'phere of -a `gas other than yair in Iorder `to .stabilize `it `and 1U to prevent 'the 'are trom Ibreaking' Vet undesired times. An extended ,period-oat eX- :periinentationon the part of prior observers yand inventors led vthe-1n to specify a hydrogen atmosphere to be the ino-stsuitable for 'this purpose, and vthis Y-statenvent has been generally A accepted as accurate. vI lhave found, however, that this statement 'is not universally applicable vto all kinds of ares, although it is still accurate so `far as I Vfain able to ascertain, if Ythe statement be flinii'ted -to arcs *in` which Vthere is "a ycarbon Aelectrode.

With fsuh 'are converters it 'has been also customary to futilize .some 'forni of liquid hydrocarbon, such :as an Aalcohol or kerosene, ttor forming'fthefatmosphere in thearc chainber, and this has been usually accomplished bysupplying the liquid Iin `a regulated drip I1-ear to 'thelextreinely hot partfot the carbon electrode. 'been understood vthat the ihydrogen 'constitnent o't ithe hydrocarbon is the 'important element, while the carbon, although not appreciably havin-ful, is not 'at all essential. 35V From the good results obtained ltroni 'the type oi are converters in general use, the 'terin"a'rc converter Vhas corne to be anden stood as an arc operating- Within anairtight chamber, in a transverse magnetic field, in an atmosphere ot hydrogen and ein 'playing `a Water-'cooled copper anode and carbon orgraphite 'eathodeland tit has been tacitly aesuinedthat 'all arcconverters may In 'such 'arrangement-s, it has thoroughly rid of all ionized Agases'or other Vconducting or semi-conducting inateriah Athe presence olf Whichfresults froinfthe yheat of? 'the arc flame. i l e higher-,the trequenc'the more 'rapid must'bethe'fscavenging which results troni thercombined*action-ofthe inag- 'netic v'field and chamber -gas. The-use ot `carbon `cat-,hodes renders more ldilicult the proper scai/*enging -on account yof the 4electronic emission `troni' the hot cathode, in Iaddition'to that of thearc itself.V Even after extinction of the faro the hot ycathode will continue vto -einit electrons, 'causing' the gap'w f to remain partially conductive. Theseelectrone, in addition 'to those found in vthearc 'l'lanie during theperiod `of ignition, Yinust be -reino'ved from fthe gap betore' lproper operation will result. i'- i;

In 'the course ot' 'development or"` acoinpact are converter capable of operationen shipboard, and that may `consume Lfull load about one :kilowatt'otelectrca flo-Wer.

l have experii'nented Ywith arcs utilizing* metal such as copper, dior both electrodes. In `atteinpting to take advantageof the teachingsof prior investigators, lV-have discovered Sonie important .phenomena Ain connection with the use l of metal electrodes that `throvvv considerable Afurther ylight on the Y'relation `bet-Ween the stability of ythe are and the atinosphere'ivithin Which`it operates.

@opper or other ymetalelectrodesare rmore desirable thancarbon,v becauselthey may be `lrept fvery inuoh cooler', as by vthe 'circulation oit -Water through thein The eiliciency is vthus 'rendered greater since there is lless elcotronic emission from thecathode, as 4is the case when carbon or g'raphicis used, "With"`- "a consequentlyniorefrapid scavenging ofthe `gap between th-eelectroclesduringthe cyclic extinction of the :This results -further in the ignition voltage' of the i are being eure Iol2 attaining its propel' value before -re"igni1 tion 4takes place, `which `promotes the elficiency` of the arc considerably. l have `found lthat ,are vconverters 'employing frnetal electrodes do vnot operate finsa stable manner ina "vaporzed condition. "I tha-ve* 'beleef' Vcracking able to correct this condition by providing an atmosplierefor the are, in a diiferent manner, and it is one of the objects of my invention to make it possible to operate` in a stabley manner an arc converter havingv metal electrodes.` Although my invention finds its greatest utility in connection with `such arcs, it is likewise applicable to arcs kutilizing carbon for their cathodes, and thus another object of my invention is to provduce an atmosphere for stabilizing the-are,

in ar novel and ellicient manner. y

5I have found that the important fand necessary step `in stabilizing the are when using .a complex hydrpocarbonsuch askerosene or alcohol, is the decomposition or rcracking of the compound intol simpler j compounds or indeed into its elements. rl`his is entirely consistent with the observed. ef-

icient operation of ar'csusin a carbon cathode, since inthis case thehigh temperature vof. the' electrode serves immediately to crack theV liquid which is dripped= upon it. Prior'investigators have failed to recognize thev importanceof thisdecomposition or n In the case of V metal electrodes, which are comparatively cool, enough heat may be generated by them eventually to vaporize or partially decompose the hydrocarbon sufficiently f to cause the are to operate as an oscillating f arc, but this can only be accomplished by allowing al current greatly in excess of the rated current ofthe converter toV flow for t periods of time varying from live to twenty Even'after the arc is brought to n an oscillating condition, its operation is unsatisfactory, the radio frequency current un minutes.

steady and the arc proneto break at unexpected moments for no apparent reason. lIn

the light of further experiments I conducted in this connectionV Ibelieve the reason for this unsatisfactory operationhas been the insufficient decomposition or cracking of the hydrocarbon. I 'believe 'that this is a consistent explanation ofthe failure of arcs l using'metal electrodes vto function properly when 'attem pts lare made to Aoperate them in the'usual manner.A

That-Sucharcsfail to function properly even whenpure hydrogen is used as an atmosphere I believe is due to `the total absence of carbon inthe arc'chainber. In the ordinary carbon cathode arc, this/carbon is very probably supplied from the electrode, but

such a source is lacking in an are using metal electrodes. For Athis reason, a carbon compound must be. used forcieating the'atmos-v,

phere, "an-d furthermore this vhydrocarbon must be in the form of relatively simple coin- Y pounds.

` That immediate effect the carbon has upon the operation to stabilize it so that it oseillates uniformly and so that it does not break, is not known to meat this time,` buty f1 am satisfied that kthe ultimatetfectis that .which I have stated. It is thus another object of my invention to supply cracked or decomposed hydrocarbon compounds to the arcr chamber.

.In order to disclose still further the difficulties encountered in operating an are using metal electrodesbefore the seemingly simple eX Jedient ofvei'a'ekin'fr' the li drocarbon wasV thought of, some incidents to theattempted operation may. be mentioned.l lith arcs using-carbon cathodes, it is a simplematter toy rotate the cathode so that thecarbon is VYevenlyconsumed. IVith copper electrodes which are kept cool by a circulation of wuter or other cooling fluid, this rotationvis impracticable. In analyzing the reason for the uneven consumption with a view toward its correction, it has been found that the transverse magnetic field bowsy outy the are between substantially constant spots on the electrode. In order to remedy this condition, it has been suggest-ed that a magnetic'field' be 'utilized wliichhas an axis parallel and not transverse to that of the arc electrodes. Demonstrations have shown,` in fact, that thisexpedie'nt causes 'the arc to travel around thetips, and the uneven consumption is thus remedied. In my investigationsto secure Aa highly eflicient are, I have embodiedthis longitudinal field in my structures, because it is so essential for thesake of efficiency to provideal (.:eoling circulating fluid to the electrodes.' It. may also be mentioned that better operating characteristics such as smoothness in'running` even with low power, are obtained whenusing longitudinal fields. This isdue probably tothe great uniformity of such'elds in the 'arc region, which tend to compress instead of elongate the arc. A further explanation of the steady operation Vof this type of arc employing metalelec- `A period of time equal inl length to many thousands of oscillations is required for the hydrocarbon to bec'omeproperly decomposed by this process and for the temperature of the. arc to return to its normal value; With ay properly cracked hydrocarbon, this `variation of temperature does not take place. On account ofthe superior operating characteristics resulting from` the use of the longitudinal-field, it was thus-.highly desirr able that l-'avail'm-.vslf Qi. S1191?. e @Strue- Cil alcohol or lerosene or the l-ile near to `"forinauc'e is evidently highly ohiectioi'i-e' .Y

cracking or decomposition oit messes tion in the ultiinate ernbodime'nt'ot a small sized efficient arc tor use on shipboard,

Upon attempting' to start the oscillations in such a longitudinal iield are by drip L i@ tips oit' the electrodes, it was 'found that not surlicient heat was produced to vapori compound. At iirst thought oneniay attenipt to drip the liquiddirectly onthe arc llame itself, but this is entirely `inn-iract-icable because the fianie (lodges about and over the active surfaces o'- the electrodos.` it maf/, oit course, he possible after a considerable interval, ot flitsen or thirty minutes, to start the oscillations, but eren then it is dii'hcult to predict hou' long it will `rcinain stable, and it may suddenly break While signaling* and Without Warning'. Such and ot hardly any use uhatsoev In the practice ot niy inven certain that t-'he hydrocarbon to the proper degreebetore it is fc are chamber. I have :toundtha ly Without any tendency 4to break or to vary the amplitude oi" the oscillations. Stat ed in a son'ieivha'. different niauner, then, an object oit inydnvention is to `insure drocarbon, either liquid or gaseous, betere itis conducted to van chamber.

This cra-citing or decomposition may be accomplished' in any Weli-'lrnonfn manner by the application ot a high heat to the coinpound. However, l prete.; to utilize electric ener y tor'this purpose. l have devised a simple and convenient retort or gasi- `tier vwhich eniploys electricity as the heating agent, and it is thus still another Aobiect oit yiny invention to provide a sunple and `reliable retort ot this character.

My invention possesses other advanta- `geous i'catures, sonie ot which, with thetoregoing, will be set forth at length y1n th'e'tollowi: g description, Where l siall outline in tull'a torniot apparatus with which my invention may 'ie practiced, and which l have selected for illustration in the .drawings accoinp.myiiigy and "forming part ot the `present specification. Although I have shown in the. drawings btt yone torni 'of the apparatus, Ido not desire to be limited thereto,

since the invention as `defined in the claims may be practicedby other apparatus, and be enbodief'l in terms.

two electrodes l?.

a completi; hy- Y nally arranged pipe f all or jacket ot4 i n ot lthe retort `,grasilier used in the systemshown in'Fig. i. Y

r; 1 l show the are chamber li in and 13, which may he made et soine metal, suchas` copper.. Tl is'arc is adapted to he supplied troni d. c. source,

li as the generator le, which is placed in series` relation with the electrodes, as Well4 with the coil 15. This coil is preferably so arranged with respect to the arc that it exerts a longimudinal lield oit magnetic torce on the are and may `tor this purpose be disposed about one or both ot the electrodes l2 and 13. A switch lo niav be `used tor-con- "necting and fi...onnecting the source 14; :troni A ratheelectrodes, as occasion requires.

diating circuit such as the antenna l?, inductor 18, and ground 19, may be connected lacross the arcelectrodes so that it may be Supplied with oscillatory current produced by the arc. 'ine toregoing description is intended to be quite general, and represents Vmerely one otinany uiell-lnoivn arc cir-Fn cuits, With `which roy invention maybe practiced. For this reason, I have made no at tempt to 'forth any particular means Ytor tuning or tor signaling since suoli arrangements forni no oiiny present invention.

For supplying the are chaniberll with an 'appropriate atmosphere described here- .inbefore, a pip 20 extends to the chamber 1li and connects therei-vith. This pipe or inlet is adapted to conduct the decomposed or yTo etliect this result, a magnet is provided, the circuit ot which is in parallel to the are, so that it is supplied with currentfrom the source le only when the switch 16 isfclosed. Needle valves. and containers hav- Ving` this saine general. system oi control vhave been utilized heretofore 4for chipping` a hydrocarhon directly into the arc chamber, and 1t is therefore considered unnecessary to describe the... eleinents in greater detail.

r*\1 Wt@ @l ,1, ,4. y 11 ine le o1!`r a as s iovvn nio@by c early in `Fie;` 2, consist-S preferably ot' a longitudior tube EEG :termine he' cracking cluunber. ',lhis tube is arrange l, eetcd to the de 'ed temperature sowas ,ct the decouipo ion, by a Couven',

source oi heat. lJn Vthepresentinstance, un

nt Q7 disposedhelelectrical heatinp; elen..n ically around the chamber is shown; .I tween this heatingeleinent and the eat il Y the 'remt there may he ced heat insulating material 28 in order to conserve `the heat as Well as to ino-intein the retort' as cool externally as possible. Connections-29 to the heating element extend through the external Wall of the retort2l and may be connected to any appropriate source, suchas the generator 14. The top-portion 30' of the retort is formed with an inlet 31 which is `vexternally threaded for connecting to the union 32 between the container 22 and the retort 2l. The supply pipe 2O leads oif from this union. The tube 26 is threaded to the extension 33 on the inside of the top 30. In this Way, after liquid drips from container 22 through'the union 32 into the retort, and decomposed or cracked in the tube 26, theresultant gas is conducted back through the union 32A and into pipe 20. The tight threaded connection between tube 26 and the extension 33 prevents any leakage of this gas.

There may at times be an accumulation of Aliquid in the bottoinof tube 26, due to an excessive supply of the hydrocarbon, Which is ordinarily preferable to an exactly regulated supply. F or draining this surplus off, I provide a drain pipe 34 connecting to the bottom of the tube 26, and controlled by a drain cock 35.y To prevent liquid thatis treated in tube 27 from immediately" dropping into the drain, a baffle 36 is placed over the pipe opening Within the tube 27. A further purpose of the baffle plate is to cause the hydrocarbon to Vspatter against the hotY interior of the metal tube. It, therefore, reaches the hottest surface in the form of finely divided sprayand the instantaneous cracking process is thus furthered vby the elimination of the necessity of it'cracking ap relatively large amount, such `as Would be represented by a single drop of liquid.

The mode of operation of the apparatus to carry out my invention is evident from the foregoing. The arc when supplied With the decomposed hydrocarbon, ymay be made to oscillate readily, and the oscillations remain extremely stable under all conditions of sigmetal electrodes are used, is accomplished by the aid of the invention as described.'

I claim: f l. In an arc converter, an arc chamber, spaced electrodes disposed in said chamber,

v,and means vfor supplying a gaseous atmosphere in said chamber including a source of n terial.

ydrocarbon material, and means remote from said electrodes for decomposing andal` tering the molecular structure of said ma- 2.. In an arc converter having a gas tight arcchamber,A the process of supplying the arcV with a suitable gaseous atmosphere,

`which comprises decomposing a relativdly complex hydrocarbon compound externally of the arcchamber, and conducting resultant gaseous mixture into the arc chamber.

' 3. The method of generating an atmospliere for the operation of an arcl converter characterized by the use of arc electrodes enclosedin a chamber, and a surface With which a vhydrocarbon materialv may be brought into contact, said method comprising applying heat 'to said surface from aY 5. In an arc converter, spacedelectrodes,

a chamber surrounding said electrodes, and

`means for supplying ay suitable atmosphere to the chamber comprising a heated retort for gasifying a hydrocarbomand means responsive to the supplying of electrical energy to the arc for rendering said retort active.

A 6. In ank arc converter, a pair of arc electrodes, means forming a gastight chamber about said'electrodes, and means for supplying a suitable atmosphere to the chamber, comprising a retort, means yfor feeding a liquid hydrocarbon into the retort, and means independent of the heat developed by said arc for heating the retort Vto a degree suiicient to decompose the hydrocarbon. 7. In an arc converter, a pair of electrodes, means forming aV gas tight chamber about said electrodes, and means for supplying asuitable atmosphere to the chamber, com-v prising a.- heated retort for decomposing a hydrocarbon, and means responsive to the supplying of electrical energy to the arc for renderingsaid retort active.

8. In 'an arc converter. a pair of electrodes,` means forming a gas tight chamber about said electrodes, and meansvfor supplying a suitable atmosphere to the chamber, com-v prising a container for a liquid hydrocarbon,

'an electrically operated valve for the con? tainer fOrpermitting it. tov discharge the liquid, a retort Within which the liquid is permitted to drip, and means for heating the retort so that it serves to crack the hydrocarbon.

9. In an arc converter, a pair of electrodes, means forming a gas tight chamber about said electrodes, and means for supplying a suitable atmosphere to the chamber, comprisingy a container for a liquid hydrocarbon, a

valve for permitting Jche container to discharge. the liquid, said valve being' operated in response to the supplying' of electrical energy to the arc, and a retort receiving the discharo'ed liquid for decomposing it.

10. ln an arc converter, an arc chamber, spaced electrodes disposed in said chamber, and means for supplying an atmosphere for said chamber comprising' a heated surface remote 'from said electrodes, and means for feeding a hydrocarbon compound into contact with said surface, the temperature of said surface being suliiciently high to instantly decompose and alter the molecular structure of said hydrocarbon.

11. In an arc converter comprising` a pair of spaced metallic electrodes having opposed faces, means comprising a longitudinal magneic field Jr'or causing` an arc between said faces to gyrate about the axis of said `electrodes, and means remote from said electrodes for supplying an atmosphere of decomposed hydrocarbon gas to said chamber.

In testimony whereof, I have hereunto set my hand.`

CORVIN C. CHAPMAN.

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