US1247027A - Vacuum regulation. - Google Patents

Description

H. C. SNOOK & E. W. KELLY.

VACUUM REGULATION.

APPLICATION FILED JUNE n, 1915,

Patented Nov. 20, 1917.

3 SHEETS-SHEET l.

HL C. SNOOK I E. W. KELLY.A

VACUUM REGULATION.

APPLICATION FILED IuNE II. I9I5.

H. C. SNOOK & E. W. KELLY.

VACUUM REGULATION.

APPLICATION man JUNE l1, |915.

1 ,$47,027. Patented Nov. 20, 1917.

3 SHEETS-SHEET 3.

KOMEN CLYDE SNOOK, OF GYN W Yy D, AND EDWIN W. KELLY 01E' PHIL xiii PENNSYLVANIA.

VACUUM REGULATION.

igaiaoav.

Continuation of application Serial No. 848,708, led July 3,V1914.` `This application filed June 11, 1915. Serial 110.153.433.

To all whom t may concern.'

Be it known that we, HOMER CLYDE SNooK and EDWIN W. KELLY, citizens of the United States, of Cynwyd and'Phladelphia,

State of Pennsylvania, have invented new and useful Improvements in Vacuum Regulations, of which the following is a specification.

Our invention relates to means for regulating the degree of vacuum of an X-ray tube or other vacuum tube.

Our invention resides in means for changing the vacuum of an X-ray tube'or other,

vacuum tube comprising an osmotic member a part of which is thick or massive for purposes hereinafter described; our invention resides in an'osmotic regulator for both raising and lowering the vacuum by means of a single osmotic member or membrane ourinvention resides in an osmotic regulator in which the regulating gas to be admitted to the vacuum through the osmotic member is liberated or produced as and when required either by electrolysis, dissociation or otherwise; our invention resides also in a regulating system involving the use of an osmotic membrane or osmotic membranes in combination with certain circuit connections and arrangements and auxiliary apparatus.

Our invention resides in the structures and apparatus hereinafter claimed. A

This application is in part a division and continuation of ourapplication Serial Number 848,708, upon which has been granted Patent No. 1,143,327, June 15, 1915.

For an illustration of some lof the forms our invention may take, reference is to be had in the accompanying drawings, in which:

Figure 1 is a longitudinal sectional view through an X-ray tube and its regulators.

Fig. 2 is a horizontal sectional view through the regulators of Fig. 1 with the circuit connections slightly altered.

Fig. 3 is a diagrammatic view of circuit arrangements suitable for the practice of our invention.

F ig. 4 is a sectional View through regu-i lators with a diagrammatic 'illustration of means for heating the osmotic members.

Fig. 5 is a sectional view through a vacuum raising and lowering regulator by which regulating gas may be produced electrolytically.

Fig. 6 is a sectional view through a vacu- "um raising and lowering regulator in which .tials.

Fig. 11 illustrates a modied form of osmotlc tube or member suitableA for use in connection with a spark gap.

' Referring to the drawings, B is the usual bulb of'an X-ray tube having the glass anode stem D and the glass ycathode stem E. Within the tube are the usual anode or target or anticathode A and the cathode C. j In the example illustrated the head 1of copper or other suitable material is'secured to the metallic tube 2, as of steel, whichkflts over the tubular glass stem 3 joinedto the stem D at 4. A tube 5,y of copper or vother suitable material, is set into the head-Il .and preferably welded thereto forming aigacuum tight joint.v The tube 5 extendsv through the stem. D and at its end is welded ory soldered at a vacuum tight joint to the platinum or othertube 6 which is sealed into the end of the glass stem D forming a vacuum tight joint. A corrugation 6a in the tube 6 yields, under expansion and contraction of the tube 5 due' to temperature changes, and therebj.T prevents breakagel of seal between tube 6 and glass stem D. Within the tube 5 is disposed a metallic tube 7 which at its inner end has anysuitable metallic projection 8 forming electrical contact with the tube 5 or head 1. Near its outer end the tube 7 is connected, as by soldering or brazing, to the metallic ferrule 9'embracing the end of the glass stem D. Electrical connection is made rom the positive terminal of a suitable high tension source of current with the ferrule 9 or the tube 7. The eXtreme end of the rammed Nomea, iai a.. l

tube 7 is connected by rubber hose or otherwise with a supply of any suitable 'cooling medium, for example a supply of air under pressure, or toy a. suction' pump or partial Vacuum.

Accordingly the air will pass into and through the tube 7, strike the head 1, from which the tube 7 is suitably spaced, extracting heat from the head1 which conducts the heat away from the target proper, the

air then passing loutwardly as indicated by the arrow through the annular space be -brazed to the platinum tube 12 sealed in the outer end of the glass cathode stem E making vacuum tight joints. 11 is a metallic tube 13, spaced at its inner end from the cathode C and having the projection 14 making electrical connection with the cathode C or the tube 11. The other end of the tube 13 is soldered or otherwise connected to the metallic ferrule 14, making an air tight joint therewith-,the ferrule 14 being secured upon the end of the outer tube or sleeve 15 of glass or any other suitable material. Electrical connection is made from the negative terminal of the aforel mentioned source of current With the terrule .14 or the tube 13 which communicates electrically with the cathode C. rl`he sleeve or tube 15 is supported upon the glass cathode,

stem' E by the member 16, of'cork or other suitable material, which has a plurality ot longitudinallyY extending grooves 17 forming air passages. c

rlhe tube or sleeve 15 preferably terminates in the bell 18 which extends around v the bulb B to any suitable distance.

Air or other cooling medium is introduced into the tube 13, passes therethrough and strikes the cathode C, cooling the same, and then passes outwardly in the annular space between tubes 11 and 13 into the sleevel or tube l5 thence through the passages 17 over the outside of the cathode stem E into the bell 18 from which it issues over the outer surface of the bulbB, all as indicated by the arrows; or in the reverse direction if tube 13 is connected to a 'suction pump or a partial vacuum. And We have found'/ that thev air or other vmedium issuing from the bell 18 clings or remains close to the bulb -B even beyond its middle or equator.`

Sealed to the bulb B is av tube 19 whose interior space 20 is in communication with f Within the tube gaarne? the interior of the bulb B. Supported by the tabel@ is the glass bulb or vessel 21 into which projects tneftube 22 of platinum,

pailadinmv or any other suitable metal or material which is capable of operation as an osmotic member or membrane. rlhe tree end ot thextube 22 is closed and its other end is sealed in the glass and its open end counicates with the' space 20. A conductor 23 connects at its one end with the tube 22 and at its other en d With-the platinum or other t wire .2t-sealed through the wall of the bulb A' second! platinum or other suitable wire 25 is sealed in the glass wall of the l bulb. 21 and `is connected by conductor 23 v with the osmotic tube 22.

It will be noted that the bulb 21 is completely sealed against the-outer atmosphere yand is s ealed against the interior space 2O communicating with the interior of the X-rayv tube B -by the osmotic member 22. ln they bulb21 is sealed an isolated charge of regulating gas for admission into the vacuum of the vbulb B through the tube 22. The gas so sealed .in ythe bulb 21 may be at atmospheric-pressure when the regulator is made,y

or may be Vabove or below atmospheric pressure, but -in any case it is preferably at a pressure high as compared withy the ,pressure within. the bulb B. The amount of gas or gases sealed in the bulb 21 is sujlicient for a great number of regulations 'of the vacuum in the bulb B, because of the very great amount of regulating gas in the bulb 21 as compared with the amount in 'the bulb lB ,at anytime.

` The gas in the bulb 21 is lpreferably'hydrogen, though it is to be understood that anyv other suitable gas or mixture of gases.

may be employed. For example, the monatomic gases, such as argon, helium, neon, zenon, etc., may be employed either singly or in combination, or in combination with hydrogen or other gas or gases.

A. second osmotlc tube or member 28 is sealed in the glass and has its open end in communication with the space 20, While its outer closed end is Within the bulb 29, which is open to the atmosphere at 30, or which may be closed or sealed and contain a gas or mixture of gases in which there is no gas of the character to be transferred from- Within the bulb B through the tube 28 into the bulb 29 for raising the Vacuum, or, more generally speaking, in which the con'- centration of the gas of the character to be removed from the bulb Bis less than it is at any time within the bulb B. A conductor 31 connects at its one end to the osmotic tube 28 and at itsother end to the platinumor other wire 32 sealed in the wall of thefbulb 29. A conductor 33 connects at its one end to the tube 28 and at its other end to the platinum or other Wire 34 sealed through the wall of the bulb 29.A

When it is desired to lower the vacuum within the bulb B, that is, raise the gas pressure therein, the tube 22 of the lowering regulator is heated by passing an electric current therethrough as from conductors 24 and 23, thence through the tube 22, and thence through conductors 26. and 25. The tube 22 being so heated, hydrogen or other regulating gas will pass by osmosis through bulb 21 through the wall of the. tube 22 to the interior of the tube 22, .thence to the space 20 and thence into the bulb B, lowering the vacuum, the pressure of the hydrogen or other gas within the bulb B being slight indeed as compared with the pressure within the bulb 21.

If on the other hand it is desired to raise the vacuum of the bulb B, that is, to take hydrogen or other gas out of the bulb B, current is passed through the conductors 32 and 31 thencethrough the raising regulator tube 28 and thence through conductors 33 and 3ft to heat the tube 28, and there being substantially no hydrogen 'or other gas of the bulb B in the air or within the bulb 29 the hydrogen or other gas will come out of the bulb B by osmotic action through the tube 28 and through its wall into the bulb I 29, notwithstanding the fact that the gas pressure'in the bulb 29 is very many times higher than the gas pressure within the bulb B.

By preference, particularly when hydrogen is used as the regulating gas, and particularly when the gas within the bulb 21 is entirely orl largely hydrogen, we make the osmotic tube 22 of platinum and the osmotic vtube 28 of the raising regulator of palladium. That is, in the lowering regulator, under the circumstances described, we prefer to use a. material forv the tube 22 through which the gas does not so readily pass by osmotic action, while the tube 28 is preferably made of a material through which the. gas will very'readily pass by osmotic action.

However, in the lowering regulator the osmotic member 22 may be made of palladium or other suitable material which passes through its wall hydrogen or other regulating gas when above a certain concentration and at ordinary temperatures. In such case we prefer to reduce the concentration of the hydrogen or other regulating gas so that when the tube 22, is at ordinary temperature it will not pass hydrogen or other regulating gas. To this end the hydrogen or other regulating gas,` whether confined or sealed in the bulb 21 or whether supplied from an external source, is diluted by admixture with some other gas which will -not at all or with very great diiiiculty pass through they osmotic material 22 when at ordinary teminverted or delivered to the outer wall of the tube 22 may be a mixture of 'substantially ten per cent. hydrogen and ninety per cent. nitrogen, and, the tube 22 being of palladium, for example, little or no hydrogen of such -concentration will pass through its wall at ycially when confined, should be such as to be' non-explosive lor non-combustible wheny raised to the temperature to which the tube 22 is raised either `by current conducted through the tube 22 as above described, o1" when using a spark gap to heat the same, as described in our said prior application and r in connection with Figs. 5 and 6 herein.

In Fig. 3 G is a source of alternating current, for example, a motor generator or rotary, supplying current through the reversing switch S and adjustable resistance 'R tothe primary 79 of the transformer T having the high potential secondary s delivering current through the synto the positive and negative high ytension vconductors P and N connected respectively to the anode A and cathode C of the X-ray tube. One'termin al of the low tension Valternating current circuit is connected by conductor 541 with one terminal of each of the transformer primaries 791 and 792 whoseothcr terminals connect respectively with one terminal of the resistance r1 and r2 adapted to be swept over or engaged by the manually or otherwise operated switch arm 55 connected to the other conductor 56 of the low tension alternating current circuit. Associated with the primaries 791 and 792 are the secondaries s1 and s2, in whose respective circuits are included the lowering and raising osmotic tubes 22 and 28. Since these tubes 22 and 28 communicate with/the interior of the X-ray tube, during operation of the ,X-ray tube' these regulator tubes assume high potentials, and consequently between the primaries 791 and 792 and their secondaries sland s2 is provided high potential insulation 57.

By this arrangement the X-ray tube may be kept in operation by energy delivered by the high tension conductors P and N and while in operation the vacuum may be lowered by bringing theswitch arm 55 into engagement with resistance r1, whereupon the secondary s1 will pass current through the e@ ing resistance to convert the electrical-enas a storage or other battery or generator of direct current, or the secondary of a transformer for delivering alternating current. The source 35 is' connected in circuit with the adjustable resistance v36- and' the double throw switch 37. When the source 35 delivers alternating or fluctuating current the member 36 may be a resistance or a re-v actance or impedance. When the switch 37 is thrown over to the right it connects with contacts 38 and 39 connected respectively by conductors 40 and 41 with the wires 24 and 25, thus conducting current through the osmotic member 22 to heat the same, the temperature being determined by the current strength which is in turn determined by the adjustable resistance 36. For heating the osmotic member 28 the switch 37 is thrown over to the left in engagement with contacts 42 and 43 communicatmg, respectively, through conductors 44 and 45 with the conductors 32 and 34 to transmit current through the tube 28 whose temperature again is dependent upon a current strength which is agaln determined by the adjustable resistance 36.

Where thev osmotic member is heated as above described, it itself operates as a heatergy into heat whose 4amount is determined by the square of the current multiplied by the resistance of that .part of the osmotic member through which the current flows..

1n F ig. 5 is shown a regulator comprising a single osmotic member 22a to be utilized for eitherrraising or lowering the vacuum with which the space 20 is in communication. The tube 22a consists of palladium, though other suitable material may be employed. 1n a bell or bulb 29a, open to the atmosphere i at 29", is a cork or `other member a through which extends the glass or other tube b in whose outer end is a cork or other stopper member c through which extends the wire or conductor al terminating in the space e between the member c and the wall f of porcelain or other porous material through which extends the platinum or other conductor g, the tube 22a`extending into the mouth of the bottle or tube b and separated by `a gap from the conductor g. The tube 22a is connected by conductor 23 to the wire 24*il which may be sealed through the wall of the member retaper 29a. The wire 25a may be sealed through the wall of the member 29a and terminate in a button 26a separated by a spark gap f from the tube 22a.

1n the space e within the bottle or tube b may be placed water, alcohol, oil, such as mineral oil, or any other suitable hydrocarbon or source of hydrogen or other gas required. c

lW hen it is desired to lower the Vacuum of the' main bulb or X-ray tube current is passed from the positive conductor d through the water or electrolyte in the space e to the conductor g andthence across the .i

gap to the tube 22a which is preferably a cathode or negative terminal. The passage of the electric energy through the material other material will be carried through member f by electrostatic action, and then decomposed into hydrogen or othergas which then passes through the heated wall of the tube 22a into the main bulb or X-ray tube to lower the vacuum.

rl`he same tube 22a may be used for raising the vacuum, by connecting the Wire 25a with the positive conductor of the circuit and ycausing the'current to leap the gap to the cathode 22a heating the same, whereupon hydrogen or other gas will pass out of the main bulb or X-ray tube through the wall of the tube 22a which is surrounded byair, and operation being the same as hereinbefore described.

In Fig. 6 there extends through the cork or other stopper a member L, of porcelain or other porous substantially nonfconducting material. The member h may be hollowed out at its inner end as shown to re ceive the end of thetube 22a. And the positive` conductor d may be connected to the member 'it in any suitable way, as by wrapping the same around the member la several times. The pores of the member k are charged with an oil or hydrocarbon or other suitable material, as described in connection with Fig. 5. A y

0n passage of current from the conductor d to the tube 22V which is connected to the negative side of the circuit by -wire 24agas will be liberated and collect within the hollow end of the member L around the endv of tube 22a which is heated by the spark or arc with the result that the gas will pass through passing current from the wire 25a across the gap to the tube 22a, which is surrounded by air, with resultant raising of the vacuum as hereinbefore described.

It will vbe understood that the structure of eitherFig. 5 or Fig. 6 may be Aused in place of the two regulators in any of the arrangements hereinbefore described and for both automatic and manual regulation.

While the structures of Figs. 5 and 6 above described are suited for the employment of current of suicient tension to jump across gaps, it will be understood that the osmotic members 22a may be heated by conduction as illustrated in Figs. 1 to 4 inclusive, or by radiation as in Fig. 7, by using low tension current. 25a may be connected directly to the members 22a without an intervening spark gap, in which case the arrangement will be the same as that indicated in the previous figures. And with such connection of the members 25a directly to the members 22a the gas may be produced by use of higher tension current by utilizing the same structures illustrated in Figs. 5 and 6 for this purpose. Or the gas may be evolved by suitably heating the gas'producing material electrically as by the same current which heats the members 22a, or by a separate current.

In Fig. 7 22 represents an osmotic member for use in any relation including the relations hereinbefore described. To heat the member 22 it is surrounded by the resistance coil 46, preferably spaced from the member 22 to allow presence of regulating gas. The coil 26 is preferably embedded in refractory non-conducting material 47. The coil 46 is connected in a circuit with any suitable source of current, as 48; and the strength of the current in the circuit may be regulated by the adjustable resistance 49. To heat the member 22 the circuit is closed bv closing switch 50 and the resistance 49 adjusted until the desired temperature is reached, the heat transfer from the coil 46 to the member 22 being by either radiation or conduction, or both.

The tube 22 may have its closed end external to the vacuum as in Figs. 1, 2, 4, 5 and 6 with the heating coil 46 also external to the vacuum. Or the open end yof tube 22 may be external to the vacuum andthe closed end and coil 46 within the vacuum.

Where there is in the bulbs 21 a vacuum regulating or other gas which would form a. combustible or explosive mixture with air which might leak into the bulbs 21 because of cracking or which might otherwise be present, any suitable vmaterial may be placed within the bulbs 21 to react with the funvwhose number of turns is adjustable.

Thus the conductors desired gas or gases to prevent forming a combustible or explosive mixture.

Such material is represented at Ph,`Fig. 4, and may be a piece of phosphorus,prefer ably adhering to the wall of the bulb 21 to prevent its displacement wher'rthe X-ray -tube and the regulators are lmoved about. Phosphorus is particularly useful when hydrogen is used because it will immediately combine with the oxygen lof any entering air and thus prevent formation of an explosive or combustible mixtureof hydrogen and oxygen. v v

In Fig. 8 the conductors 54 and 56 supply low tension alternating current to the transformer T, R being an adjustablel re.- sistance. in the circuit of the primary p The high potential secondary s delivers uni-directional high tension current through the rectifying switch F, as in Fig. 3, to the positive and negative conductors P andl N.

The anti-cathode A is connected to yan osmotic member 22, of either a vacuum lowering or raising regulator, and to a spark gap terminal 58. The associated sparkgap terminal 59 connects through conductor P to the rectifying switch F. Disposed near the tube 22 is the spark gap terminal 60, the tube 22 and terminal 60 forming a spark gap whose terminals are connected in parallel with the spark gap terminals 58 and 59. Disposed near the' spark gap . terminals 58 and 59 is the con-ducting member 61 supported upon the end of the insulating member 62 carried bythe armature 63 of electromagnet 64 and pivoted at 65.V A spring 66, under tension, connects at its one end to the armature 63 and at its other end to the adjusting screw 67 which adjusts the tension of the spring 66. The electro-magnet 64 has its one terminal connected to the conductor 54 and its other terminal to the adjust-f the circuit of the electro-magnet 64 1s 1n shunt to a'part of the primary p. Associated with the movable contact 69`is the scale 71 reading in units corresponding with different degrees vof vacuum of the X-ray tube.

Assuming the osmotic-tube 22 to be part of a vacuum lowering regulator, and the vacuum to be too high, the fall of potential across the primary p will. be high, especially if the magnetic leakage of the transformer T is low, with resultant greater current flow through the electro-magnet 64, with a given setting of the contact 69. Accordingly the electro-magnet .64 will at tract its armature 63 in opposition to the spring 66 and remove the member 61 from cthe terminals 58 and 59, thereby producing a spark gap or increasing the length of a spark gap, with the result that the energy passed between the tube electrodes A and C will leap the gap between terminals 60 and tube 22 to heat the latter and cause a lowering of the vacuum as hereinbefore described. As the vacuum is lowered the fall of potential across the X-ray tube will diminish, as will also the fall ofpotential across the primary p, and accordingly the strength of current through the electro-magnet 64 will diminish and the spring 66 will withdraw the .armature 63 and shorten the spark gap at 58, 59 and 61 so that the energy through the X-ray tube will no longer jump the gap between 60 and 62, but will pass from contact 59 to contact 58 through member 61, with the result that the tube 22 will cool and the vacuum will be no further low ered.

When the tube 22 -1 is that of a vacuum lowering regulator the movement of the contact'69 toward the right, therebycutting out some of resistance 68, will insure the automatic maintainence of a low vacuum., while movement to the left will insure automatic maintainence of a higher vacuum.

In this arrangement of Fig. 8, therefore, there is a spark gap for controlling a vacuum regulator, which spark gap is in series wlth the X-ray tube proper; and this regulator spark gap is shunted by another spark gap whose length is automatically varied in response-to degree of vacuum of the X-ray tube.

In Fig. 9 the arrangement in the primary circuit is similar to that in Fig. 8 except that the electro-magnet now takes the forni of a solenoid 72 whose core 73 is attached to the insulating lever 62 pivoted at 65 and controlled by spring 66 which is in turn adjustable by. .the screw 617.

The X-ray tube is here shown as provided with both a vacuum lowering regula-tor and a vacuum raising regulator, the former comprising the osmotic tube 22 and spark gap terminal 60 and the latter comprisingr the osmotic tube 28 and the spark gap terminal 74 connected through positive conductor P to one terminal of the rectifying switch F.

The tube 28 is connected to the spark gap terminal 60 and to the conductor75. 'lhe tube 22 is connected to the anode of the'X- ray tube and to the conductor 76, and the spark gap terminal 74 is connected to the conductor 77. rlihese conductors 75, 76 and 77 are disposed adjacent each other 'but at such distance from each other that sparking does not occur between them. Movable across and near the conductors 75, 76 and 77 is the conducting member 61 carried by the lever 62. rlhe `arrangementot the conductor 61 and the conductors 75, 76 and 77 is shown in Fig. 9a. v

- Here again the solenoid 72 becomes more mesma? weakens as the vacuum lowers.

As the vacuum rises the lever 62 will be. drawn to the left-by the solenoid 72 until the member (i1 passes/beyond the conductor 76 and bridges only conductors 75 and 77, whereupon the current vis passed from the high tension switch l" through the conductor P to conductor 77 to conductor 61 to conductor 75 and to spark gap terminal 60, and thence across the gap to the tube 22 and thence to the X-ray tube. This heats the tube 22 with resultant lowering of the lf the vacuum becomes too low the spring 66 will draw the member 62 to the right until the member 61 passes beyond the right end of conductor 77, whereupon current will pass from conductor P to spark gap terminal 74 and thence acrossthe gap to the tube 28 and thence. to conductor 75, to conductor 61, to conductor 76 and thence through the X-ray tube. Accordingly the tube 28 is heated and the-vacuum raised..

The setting of the contact 69 will cause the apparatus to automatically maintain a vacuum between certain upper and lower limits, which limits will vary withv adjustment of the contact 69. l

lin Fig. 10the automatic regulation is procured in response to fluctuations in potential of the high tension circuit across the anode and cathode of the X-ray tube. .This method of regulation is thereforeyavailable whether or not the high tension transformer 'll` has small magnetic leakage.

The high tension positive and negative conductors P and N connect with the anode and cathode respectively as described. However, in one of these conductorsfas P, there is a spark gap between the stationary terminal 78 and the adjustable terminal 79, the energy passed through the Xray tube passing over the gap between these terminals. In this case the current for heating the regulator tubes 22 and 28 passes over the spark gaps. Connection for this purpose is made from positive conductor F to the conducting member 80 pivoted at 8l and controlled by the torsion spring 82 whose free end carries a pointer 83 which may be clamped in any desired position with respect to the scale 84, similar to the scale 68 in Fig. 8, as by fricstrongly energized as the vacuum rises and 65 Ation between the scale and pointer. The

lill@ opposite end of the beam 8O is an adjustable counter-weight 93 for balancing the beam so that its normal position shall be indicated.

In normal operation the high potential energy will leap across the gap between terminals 78 and 79 and pass through the X-ray tube to energize the same. This spark gap length is less than the sum of the lengths of the spark gaps between 86 and 88 and 88 and 28, aiidlessthan the sum of lthe lengths of the spark gaps between 85 and 87 and -87 and 22, with the result that normallycno current will pass over these regulator spark gaps. Under normal conditions the electrostatic charges on arcs 90 and 91, being of similar sign, cause these arcs to repel each other,y and this repulsive force coperating with the counterweight '93 and the spring 82 maintain the beam 8O balanced as shown. If however the vacuum of the X-ray tube should raise. the potential across the `X-ray tube terminals will increase and the potential of the arcs 90 and 91 will be higher and they will repel each other with greater force, tilting the beam 80 in a clockwise direction about its pivot 81 bringing the terminal 85 closer and closer tothe conductor 87 so that eventually the spark gap at these regulator terminals is shorter than the spark gap between the terminals 78 and 79 whereupon the current will pass through the regulator spark gaps atthe right heating the lowering regulator tube 22 causing the vacuum to be automatically lowered.

And if the vacuum has raised to a great eX tent the unbalancing of the beam 80l will be so great as to bring contact 85 into engagement with contact 87, which latter then acts as a stop for the beam. v

On the other hand if the vacuum of the tube is too low it will be automatically raised because of the decrease of potential of the arcs 90 and 91 allowing the beam 8O to move in a counterclockwise direction on its pivot 81 to shorten-the gap at the terminal 88, thereby causing the currentto pass across the spark gap between 86 Vand 88 to heat the raising regulator tube 28, causing theV ali/to"- matic raising of the vacuum. By adjusting the screw` contacts 79, 85 and 86 the amount of Variation of vacuum to either side of that indicated by the scale 84 may be adjusted.

If the connection 92 between the arcs 90 and 91 is omitted and when in such case the ai'c 90 remains as indicated in the drawing or is connected to the positive conductor P, in such latter case substantial insulation intervening between arcs 90 and 91. the arcs '90 and 91 will carry charges of opposite signs and twill therefore attract each other. And this attractive force will var v with the potential difference across the X-ray tube terminals and therefore with the degree of Vacuum. Withfalling vacuum the attrae' tion between the arcs 90 and'91 will become less and the beam 80 will thenmove 1n a clockwise direction about its pivot 81. Accordingly vfor this arrangement the arcs 90 and 91 and the counterweight 93 should be interchangcd asto their positions with respect to the beam 80, orthe spark gaps for the regulator tubes should be interchanged.

It will be understood also that in place of l osmotic regulators described in connection with Fig. 10 the ordinary gas evolving regulators maybe used in association with the spark gaps described, the energy passed over these gaps serving to liberate the vacuum regulating gas. f

-It will be understood that While osmotic' regulators have been described in connection with Figs. 8,` 9 and 10, that any other type of regulator may be used, as for example, the ordinary regulators involving material which upon being `heated will evolve gas within the vacuum,- the spark gaps of these figures being used to pass energy to` such ordinarv regulators. In Fig. 11 the osmotic tube, 'as 22,' is shown with a thickened end 22e which may be used as the terminal of the spark gap,

such thickened end 22e withstanding greater 1 l heat than the thinner parts or walls of the tube 22. The` thickened end of the tube 22 may be produced in any suitable way, as forV example. by fusing the closed end of the tube 22 until it thickens, as illustrated.

f It will be understood that the osmotic members or membranes hereinbefore de- .scribedmay take other`than the tubular freely than platinum. By alloying platinum and palladium. however, there results an osmotic material which passes hydrogen with less facility than palladium alone. Such alloys may with advantage be used with different partial pressures of the reguice lating gas or gases and with different degrecs of dilution of the regulating gas or gases. #7 i lVhile the air cooling of ,the X-ray tube hereinbefore described is of advantage, it will be understood that our invention is not limited to the use of our herein claimed exterior of said wall exposed to the atmos-4 claim in ourl application Serial Number' .195,009, filed October 6, 1917, certainsubject matter not herein claimed.

What we.claim is:

1. Means for regulating the vacuum of a vacuum tube comprising an osmotic memberforminga wall of said tube, dierent gases external to said tube in contact with said osmotic `member, said member when heated adapted to allow passage therethro-ugh of one or more of said' gases and to exclude another orothers of said gases, and

means for electrically heating said member including a spark gap in proximity' to'saidi member.

2. A'ragulatoil for the vacuum of a vacu-f um tube comprising an osmoticmember, amass of porous material charged with gas`- evolving material disposed in proximity` to 'said member, and electrical,connectionsl to 'said member and said porou's material.

3. A regulator for the vacuum of a vacu- 1 um tube comprising an osmotic member, a mass of porous material charged with gas evolving material disposed in proximity pito.- said member, electrical connections to said i member and said porous material, and a` spark gap terminal spacedfrom said member.

l. A regulator for the vacuum of a vacuum tube comprising an osmotic member, a container for electrolyte, said container having a porous wall, electrical connection into said container, a conductor extending through said porous wall and spaced from said member. 4

5. A regulator for the vacuum of a vacuum tube comprisingv an osmotic member, a container for gas evolving material, said container having a porous Wall, .and a conductor extending through said container and aid porous wall and spaced from said meiner. v

6. The combination with a vacuum tube, of a regulator for raising and lowering the vacuum of said tube comprising an osmotic member forming a wall of said tube, gas evolving material. means for subjecting said material to the eiiects of-an electric current to cause evolution -of gas, means forelectrically heating said osmotic member for allowing passage of the evolved gas therethrough, and means for electrically heating said member without evolution of gas for passageof gas from said vacuum tube to the exterior of said osmotic member.

7. A regulator for the vacuum of a vacuuml tube comprising an osmotic member forming a wall of said tube, a portion of the phere, means for supplying regulating, gas

in connection with an air cooled werpen to another portion of the exterior ofvsaid member, and means for heatin said inember for causing passage of gas t erethrough to or from the interior of said tube.

8. A regulator for the vacuum of a vacuum tube comprising an osmotic member `forming a wall thereof, gas evolving material in proximity to said member, a conductor disposed in proximity to said member, and Imeans for passing current through said conductor and said gas evolving material.

9. An osmotic'member or membrane having althin gas passing portion and an integral -massive portion. n

10. An osmotic member having integral thin and massive portions,`and means for 30 raising the temperature of said massive portion'. whereby heat is conducted to said thin portion. y v l ,11. An osmotic member comprising integral thin and massive portions, said massive portion forminga terminal of a spark gap.

12. The combination with an X-ray tube, tof a spark gap in series therewith, a v acuum regulator comprisingpa spark gap in parallel with said first named spark gap, and

means for' altering thel length of ,one of' said ga s.

13. '1 e combination with an X-ray tube, of a spark gap in series therewith, a vacuum regulator comprising a spark ap in parallel with said first named spar gap,4 and means responsive to change in degree of vacuum 'of said X-ray tube for altering the length of one of said spark gaps.

14. The combination with an X-ray tube, 10( of a spark gap in series therewith, a vacuum regulator comprising a spark gap in parallel with said first named sparky gap, a movable member adapted to change the length of one of said spark gaps, and electro-magnetic means controlling said member.

15. The combination withv an X-ray tube, of a spark gap in series therewith, a vacuum regulator comprising a sparkY gap in parallel with said rst named spark gap,a movable member adapted to change the length of one of said spark gaps, and electro-magnetic means responsive to changes in degree of vacuum of said X-ray tube conv trollin said member. 115

16. y he combination withl an X-ray tube, of a spark gap in series therewith, a vacuum regulator comprising a spark gap in parallel with said first named spark gap, a movable member adapted to change the length of one of said spark gaps, a step-up transformer supplying said X-ray tube, and electromagnetic means connected in the primary circuit of saidv transformer controlling said member.

17. rllhe combination with an X-ray tube, of a spark gap in series therewith, a vacuum regulator comprising a spark ygap in paraliia lel with said first named s ark gap, a movable member adapted to change the length of one of said spark gaps, a step-up transformer supplying said X-ray tube, and electro-magnetic means connected in parallel with the primary winding of said transformer controlling said member.

18. The combination with an X-ray tube, of a spark gap in series therewith, a vacuum regulator comprising a spark gap in parallel with said first named spark gap, a movable member adapted to change the length of one of said spark gaps, a step-up transformer supplying said X-ray tube, and electro-magnetic means connected in parallel with a part of the primary of said transformer controlling `said member.

19. The combination with an X-ray tube, of a spark gap in series therewith, a vacuum regulator having a spark gap, said spark gap connected in parallel with each other, and means for varying the length of said first named spark gap.

20. The combination with an X-ray tube, of a spark gap in series therewith, a vacuum regulator havin a spark gap, said spark gaps connected 1n parallel with each other, and means responsive to the variations in the vacuum of said X-ray tubevfor varying the length of. said first named spark gap.

21. The combination with an X-ray tube, of a spark gap in series therewith, a vacuum regulator having a spark gap, said spark gaps connected in parallel with each other, and means for varying the length of said regulator spark gap.

22. The combination with an X-ray tube, of a spark gap in series therewith, a vacuum regulator having a spark gap, said spark gaps connected in parallel with each other, and means responsive to the variations in the vacuum of said X-ray tube for varying the length of said regulator spark gaps.

23. The combination with an X-ray tube, of vacuum raising and lowerin regulators comprising spark gaps, means or shunting said spark gaps, and means responsive to changes in degree of vacuum of said X-ray tube controlling said means.

24. ,The combination with an X-ray tube, of vacuum raising and lowerin regulators comprising spark gaps, means or shunting said spark gaps, and electro-magnetic means responsive to changes in degree of vacuum of said X-ray tube controlling said means.

25. The combination with an X-ray tube,

' of vacuum raising and lowering regulators,

a spark gap for each of said regulators, a spark gap in parallel with each of said spark gaps, and means for varym the length of a spark gap of each pair o parallel connecting spark gaps.

26. The combination with an X-ray tube, of vacuum raising and lowering regulators,

a spark gap for each of said regulators, a spark gap 1n series with said tube and in paralle with each of said spark gaps, and means for varying the `length. of a spark gap of each pair of parallel connected spark gaps- 27. The combination with an X-ray tube, of vacuum raising and lowering regulators, a spark gap for each of said regulators, a spar-k gap in parallel with each of said spark gaps, and means responsiverto variatlons 1n degree of vacuum of said X-ray tube for varying the length of a spark ga of each pair of parallel connected spar gaps.

28. The combination with an X-ray tube, of vacuum raising and lowering re ators, a spark gap for 'each of said regu ators, a spark gap in parallel with each of said spark. gaps, and electro-magnetic means responslve to variations in degree of vacuum of said X-ray tube for varying the length of a spark gap of each pair of parallel connected spark gaps.'-

29. The combination with a vacuum tube, of a vacuum lowering and raising regulator,l a scale having marklngs corresponding with degrees of vacuum an index associated with said scale, means for controlling said regulator including electro-magnetic means, and means determining the operation of said controlling means set with said index.

30. The combination with a vacuum tube, of a scale having markings correspondin with degrees of vacuum, an index associate with said scale, a vacuum regulator, and means for controlling said regulator comprising electro-magnetic means and means set by movement of said index.

' 31.- The combination with a vacuum tube, of a vacuum regulator, a scale having markings corresponding with degrees of vacuum, an index associated with said scale, means for controlling said regulator including electro-magnetic means, and current-regulating means determining the operation of said controlling means set with said index.

32. The combination with a vacuum tube, of a scale having markings corresponding with de ees of vacuum, an index associated with sa1d scale, a transformer for exciting said vacuum tube, a vacuum regulator, means in shunt with the primary of said transformer for controlling said regulator, said means comprising an electro-magnet and current-regulating means set with said index.

33. The combination with a vacuum tube, of a scale having markings correspondin with degrees of vacuum, an index associated with said scale, a transformer for exciting said vacuum tube, said transformer having low magnetic leakage, a vacuum regulator. means in shunt with the primary of said transformer for controlling said regulator, said means comprising electro-magnetic means and current-regulating means, said current regulating means being set with said index.

34. The combination with a vacuum tube, of a vacuum regulator, la transformer for exciting said vacuum tube, said transformer having low magnetic leakage, means in shunt with the primary of said transformer for controlling said regulator, said means comprising electro-magnetic means and current-regulating means.

35. The combination With a v acuum tube,

of a vacuum regulator comprlsing an osmotic member a transformer for exciting said tube and supplyingcurrent to said regulator, said transformer having low magnetic leakage, and electro-magnetic means in 20 electrical connection With the primary of mamar said transformer for controlling said regulator. A

36. The combination with a Vacuum tube, of a Vacuum regulator comprising an osmotic member, a transformer for exciting said tube andsupplying current to said regulator, and electro-magnetic means in electrical connection With the primary of said transformer for controlling said regulator.

37. ln a vacuum regulator, an osmotic member of material containing platinum and palladiuml 38. In a vacuum regulator, an osmotic member composed of an alloy of platinum and palladium.

In testimony whereof We have hereunto ailiXed our signatures this 10th day of June,

HOMER CLYDE SNOOK. EDWIN W. KELLY.

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