Патент USA US2128070код для вставки
Aug. 23, 1938. 2,128,070 w. E. BAHLS 'ELECTRIC DISCHARGE DEVICE Filed Jan. 10, 19:56‘ 5.9 WITNESSES: INVENTOR MZZBI'EBd/Z 25. BY \7.‘ I ATTORN 2,128,070. Patented ‘Aug. 23, 1 UNITED STATES mes-r OFFICE ‘ ' 2,128.0" nwcrnrcnrscnsaoa navron 'Walter E. mm, Wilkinaburg. Pa” alaignor to Westinghouse Electric a Manufacturing Com pany, East "Pittsburgh, Pa” a corporation of Pennsylvania Application January 10, 1938, Serial No. 58,533 (Cl. 250-275) Fig. 6 is a circuit diagram‘ illustrating one use This invention relates to space discharge de 3 vClaims. vices and is particularly adapted to those devices which have a hot cathode and gas or mercury vapor or‘ a combination of ‘the two for their I a cathode 3. ‘working atmosphere. It is an object of this invention to produce a‘ 10 II 25 30 35 40 The cathode is provided with a heating circuit including leads I and 6 which device of the class described which may be used for a recti?er having a high current-carrying ca? extend through the press 2 to the ends of the following description and the accompanying cathode is also within the envelope. cathode proper 3. The cathode proper consists pacity and being capable of withstanding a heavy of a corrugated ribbon wound into helical form and secured to the two leads 5 and 6. From one difference of potential between the anodes with of the leads depends a support ‘I holding a sup out back?re occurring. ply 8 of a getter-metal'which acts as a clean-up ‘It is a further object of this invention to pro device when freeing the tube from gas prior to vide a device of the class described with an elec filling it with the desired atmosphere. trostatic shield which assists in preventing back The tube has two anodes l0 and H supported 15 ?re and‘ also may act as a grid to control the from the press by leads l2 and [3. »Where the starting of the current. It is a further object 01 the invention to pro- ' lead I2 emerges from the press, it is surrounded vide a circuit such that the single grid controlling by an insulator M which may be the same glass the device having a‘ cathode and a plurality of as the press or may be other ceramic material. anodes may have impressed upon it a controlling Similarly, the lead I3 is surrounded with insu 20 lator IS. The insulators i4 and I5 surround the potential. ' leads substantially up to the terminal blocks II It is a further object of this invention to pro vide a circuit of the sort described in which the and II which constitute the anodes‘ proper. A hollow cylinder l8 surrounds the anode HI part of the cycle during which any one anode carries current may be a predetermined fraction and a cylinder l9 surrounds the anode II‘. The 25 cylinders may be made of sheet metal and pro-. of a cycle. 1 vided with ?anges 2| and 22 by which the two It is a further object of this invention to ‘pro halves of the cylinders are joined together. A vide a shield which shall act as a barrier sepa similar ?ange 23 constitutes the middle portion rating the anodes. ' of the shield and the junction of the two cylin 30 It is a further object of this invention to so The shield as a whole namely l8, l9, 2|, 22 locate the openings in said barrier that they ders. and 23 is designated 24 and it may be supported shall, in effect, provide substantially distinct from the press by a standard 25. It is electrically paths between the cathode and the several an although it may have been made of odes, and any particular path shall be free and _ continuous several portions united together. As shown in 35 unobstructed between the cathode and its anode. It is a further object of the invention to so the illustration, the ?anges 2|, 22 and 23 are spot welded together but any other desirable way select the atmosphere in the tube, gas, mercury of uniting them into an electrically continuous vapor, or mixture of gas and vapor, that the arc whole may be employed. It is unnecessary to re drop and the starting potential shall have the 'de sort to connections outside the tube to make the 40 sired values. whole shield electrically continuous but all parts Other objects of the invention and details of of the shield are connected within the envelope the proposed structure will be apparent from the and if desired the connection of the shield to the drawing, in which 45 of the device. In Fig. l, the device is provided with an en velope I having a press 2 upon which is mounted _ ' ‘ The inside of the envelope is equipped as Figure 1 is a central vertical sectional view of shown at 26 with a conductive coating prefer one form of my device. a ably formed by covering the inside or the en Fig. 2 is a similar view, the plane of the sec velope with a graphite solution. A conductor 28, tion being at right angles to that of Fig. 1. preferably of very ?ne ?exible wire, extends up Fig. 3 is a similar section of another form of _ward from one terminal of the cathode 3 into my device. ’ . Fig. 4 is a sectional, view taken on the line IV—IV of Fig. 3.. Fig. 5 is a sectional view taken on the line V-V 01' Fig. 4, and contact with the coating 26. The whole of the inside of the envelope is not coated, but only‘ the portion adjacent one end of the space discharge paths. In the form shown in Figs. 1 and 2 the coating extends slightly below the upper end of 55 ,\ j ' _ . ' _- 8,198,070 ' _ . . . the shield 34.‘ In thefform shown in?!‘ 3'the . cated in Fig. 6 ‘by ‘the lead‘, II. For supplying coating extends slightly belowthe anodes. ‘ ‘power to the anodes a transformerv "is shown The thin and flexible wire 23 is at one " in Fig. 6. A small secondary of the same trans end of the cathode, and the cathode, anodes and , former or of another, .not'shown, is indicated at 5 shield are mounted in the press before-the press ' I53, as supplying the leads I and I and the oath is united with the rest of theenvelope. Whenv the tube is completed by putting the press into Each anode is connected to the respective end its place within the rest of .the envelope, the of the secondary of transformer 53. 4 The center ‘wire 23 comes into contact with the coating 2'; of said secondary is connected to the center of 10 No special care need he exercised in determining the secondary 53 and thus to the cathode. The the length of the wire 23, as it is made long connection includes the load which is represent 10 enough to surely contact the envelope and can ed by the resistor 54 although it ,need not be bend to accommodate itself to the space in which merely‘ resistive. ' it is finally located. r _ The primary 5! of a transformer I‘ is illus 15 It will be'seen upon inspection of the shield trated as connected in parallel with the primary ‘ shown inv Fig. 1 that there is a direct line from of transformer 52. The transformer 3! includes 15 the anode ‘l0 to the left hand part of the cath-, ‘a primary 55, a coil 51 and a secondary coil II. ode 3 uninterrupted by the shield and similarly The coil 51 is connected to the'same terminals .a. direct line from anode II to the right-hand as the coil 55, an adjustable resistor 53 being in part of the cathode 3 is not crossed by the shield. cluded in ‘one connection. The electromotdive By a direct line I do not necessarily mean a forces induced in the secondary 53 are dependent straight line, but one over which ions can travel both as regards phase and intensity on the ad . without change of direction abrupt enough to Justment of the resistor 53. The coil 53 delivers materially increase the ‘likelihood of the ions go current to a full wave rectifier 83, preferably of 25' ing somewhere else instead of to the cathode, the copper oxide, type, whereby current flows In Fig. 3_ the anodes ill and H are at the up through one-half of the coil 33 and one-half of per ends of standards continuous with the leads the full-wave rectifier during one-half cycle, and I! and I3. The cathode is heated through leads through the other half of the coil and the other ,I and 0 which extend to. its twoends, as shown half of the rectifier during the next half cycle. ode. most clearly in Fig.‘ 5. A trough-shaped portion ' , . The transformer is so designed that the current delivered by the secondary 53 has a sudden rise to a maximum each half-cycle with small current 30 of the shield surrounds the cathode except at the top thereof and is equipped with insulators 3| and 32 through which the leads 5 and 6 ex tend. The trough "is open at the top and the 35 opening is divided by a shield 33 which extends between the anodes it‘ and it into the space sur during the other portion of the half cycle._ Al though the drawing indicates one way of design ing such a transformer, other ways may be used‘. rounded by the coating 26. 7 The shield 33 is supported bytwo portions 35 and 36 which extend downwardly along the end walls of the trough. The central portion of the shield 33 extends into the interior of the trough, abutting the inner face of the end portions as ‘shown at 3'8 and 38. The lower edge 38 of the The return connection from the recti?er to the middle of the coil 58 is through a resistor 30. A connection between the end of the resistor 80 nearest the recti?er and the shield 50 is made by means of a resistor 6|. A battery 82 is connected between the end of the resistor 60 nearest the transformer 55 and the middle of the second ary 53. shield is as near to the cathode 3 as it can con veniently be located without danger of contact therewith. The trough 30 is supported by a pair of standards 4! and 42 which are joined together ' and supported from the press as clearly shown ' When the tube is completed and evacuated it is filled with neon or other desired gas to the pressure decided upon. A small amount of mer cury is also’ introduced if desired. With low pres sure gas only the voltage drop along the arcs in Fig. 3 at W. A weld or other securing means , formed between cathode and the several anodes illustrated at 48 unites each standard to the is greater than if mercury also is present. With trough. ' - It will be noted that the shield of Fig. 3 af-‘ i'ords a direct line from the left hand partvof cathode 3 through the left hand half of the top of the trough to anode i0 and a direct line from the right hand part of the cathode through the 5 right hand half of said top to anode Ii. . In Fig. 6 the cathode leads 5 and 6 and the anodes I0 and II are identi?ed by the same 60 numbers. The shield designated 50 in Fig. 6 may have either the form'shown in Fig. 1 or that shown in Fig. 3, or any other desired form. The standards supporting the shield are illustrated _ in Figs. 1 and 3 as if they terminated in the 65 press. , _ , The coating 26 in Fig. 3 is connected by a fine flexible wire 23 to the shield. The coating is thus kept at the same potential as the shield. JI‘his is different from the arrangement of Fig. 1 0* in which when the shield connections are inside of the envelope the coating is connected to the other end of the cathode from the shield. If it is desired to control the potential of the shield by connections outside of the envelope, the stand “ ard must extend through the envelope as indi -mercury present the current characteristics of the tube vary with temperature. The djvice illustrated in Fig. 1 can operate with th shield disconnected from all external connections or with "the shield connected to a system such as is shown in Fig. 6.‘ If desired, connection between the shield and a pointy of ' predetermined potential, such as one end of the cathode, may be made within the tube. The standard 25 does not then extend outside of- the press. When this connection is used, the ?exible connector 28 is connected to the opposite end of the cathode 3 so that the shield is -at the poten tial of one end of the cathode 3 and the interior coating is at the potential of the opposite end. When the tube is thus connected, during the half cycle when the anode I 0 is positive, elec trons ?ow from the cathode 3 to the anode II. In the are thus established, there is a drop in potential close to the cathode v3 the gradient of 70 which is much greater than the gradient through out the rest of the arc. In this space where the gradient is large, the electrons from the cathode travel at a speed sumcient to produce more ioni zation than elsewhere in the gas with which the 75 . - _ > tube is filled. , - .' ‘ 3 9,128,070‘ hand, the shield can act as a grid, preventingthe are from starting to the positive anode until a certain critical potential has been passed. The nearer the edge of the opening 'in the shield to region, ‘surrounding the cath ' ode .and- usually not very thick ~‘ is called the cathode space-charge sheath. The sheath in which the electrons produce most ionization in. the gas has a well-marked the cathode, the greater is this grid effect. It is, becomes greater this region becomes more nar distance of ten times the thickness of the space therefore, undesirable to have the shield much boundary. 'Its thickness varies with the pressure ‘closer to the cathode than the above-speci?ed and the current density. As the current density - row. charge sheath. Within this region the ions which are attraction from the cathode. Most of these ions fall into the cathode but not with su?lcient ve cur for even at high potential a discharge will. not form between the anodes. Around the nega tive anode the shield and coating present a region where the field is insufiicient compared to the field 15 locity to damage it because ‘the distance they fall Electrons which escape from the space charge sheath move to the anode Hi. There will 15 not be much acceleration of these electrons be— ' is small. of the cathode to move ions to the negative anode tween the boundary of the space-charge sheath and the anode because the potential gradient here in sufilcient number to form an arc. ' The nega is small. It is small because the space charge to be overcome is small, being largely neutralized by the ions present. The ions here are acted being established. tive anode is thus protected from anarc thereto sheath. " That is the ions in the long part of’ the arc diffuse more than those in the narrow space-charge sheath. The ions within the sheath do not diifuse much because of the stronger elec trostatic forces there. The diffusion of ions tends to produce ionization throughout the tube but negative anode. Although the negative potential anode ll, very few ions will enter. Ions between the mouth of cylinder l9 and the cathode are attracted by the cathode 3, which has a negative potential. The anode II has a much stronger negative potential but it is sur; rounded by the cylinder I! which is at the po tential of one end of the cathode. The space between the cathode 3 and the adjacent mouth‘ of charge sheath, outside of which ions~may diffuse, but ,within which little diffusion occurs. Ions may proceed by diffusion to fill the space on one side of the partition 33 within the trough and 40 form an arc stream between the trough and the positive anode, but few ions will be present in the tube on the side of the partition 33 toward the the cylinder I 9 is near the coating 26 which differs from the potential of the shield‘ I9 by s negative anode. i - When it is desired that the shield shallact as a grid in either form of the device, it may be connected to an external source of potential, as indicated in Fig. 6. At the beginning of any par The attraction of the negative anode ll upon the ion between the cathode 3 and the opening at the upper end of the cylinder l9 is'largely neutralized by the shield 24 and the coating 26. ticular cycle, current will ?ow through the resis tor- Bll and through one-half, of the rectifier 63. This current is toward the left in Fig. '6. The right hand end. of the resistor 60 is therefore more positive than the lower end of the battery 82 and They therefore move toward the cathode 3. It is different with‘ the ions between the oath ode 3 and the mouth of the cylinder It. The anode Ill therein is strongly positive at the time and an arc is maintained between it and the cathode 3, the ions in said are moving toward the cathode and the electrons therein. moving to ward the anode in the usual way. Therefore, al though the ions in the long part of the arc stream can diffuse and do diffuse, very few of them enter ‘ the region enclosed by the cylinder around the anode ll. When thereversal of the potential being rectified occurs, and‘the anode H becomes positive, while the anode III becomes negative, the arc stream will form between’the cathode 3 andv the anode l I and the cylinder l8 of the shield will prevent the ions from proceeding to the (now negative) anode l0. cathode.‘ If preferred the. potential of the shield may be controlled by connections extending out-‘ side the envelope as illustrated in Fig. 6, or by other external connections if desired. This bar rier prevents ions from being attracted by the of the negative anode is strong compared to the negative potential of the cathode, the ions do not proceed to the negative anode because of this electrostatic action of the shield. Around the cathode .is formed the above-described space into the cylinder I3 surrounding the negative. > I lar considerations apply. The anodes are not surrounded by the shield in this form, but a bar rier is presented by the shield 33 which, together with the trough 30, affords an electrostatic shield at a potential corresponding to one end of the that within the space-charge sheath. The er ‘ratio motion of the ions, similar to ‘that of gas molecules, therefore, produces a more readily recognized effect here than in the space-charge only a small amount. , In the modi?cation shown in Figs. 3 to 5, simi upon by a-potential gradient “small compared to ‘ In order that this action may take place de p'endably,-although the di?erence in potential be ' tween the anodes be high, it is necessary that the edges of the cylinders l8 and I 9 be fairly. close to the cathode 3. In general it may be said that the distance from the cathode to the nearest edge of the opening in the shield ought not to be more‘ than ten times the thicknessof the above 75 described space-charge sheath. 0n the other 70 ‘ The device can be used effectively with high anode potentials because back-?re does not oc 10 formed by the ionization are subjected to strong the drop over the resistor must be subtracted from the potential provided by the battery to ob tain the potential of shield 50. When the result ant potential of the shield is no longer sufficiently negative to prevent the formation of an arc, the arc starts. By proper adjustment of the resistor 59, and, if necessary, adjustment of the ratio be tween the potential of the battery 62 and the re sistance of the resistor 60, this critical potential of the shield may be reached at any desired period in the half cycle. All of these adjustments except that of the resistor 59 are preferably permanent and made when the apparatus is ?rst designed or manufactured. The anode, which is at this time active, can be made, therefore, to carry current during only a fraction of that half cycle, and thus the average current carried-by that anode can be 10 regulated. During the next half cycle, the current ?ows through the other half of the recti?er 63, but is in'the same direction through the resistor ill, and, the shield therefore, arrives at, the critical poten- 75 1 4 3,128,070 _ v tial at the same fraction of the next hall’ cycle. ‘cooled. The ?lament consists of seven turns- 01-‘ . The other anode will thus carry an adjusted por; corrugated ribbon, .075 inch wide, and .007 inch . I tion of current in the same way. _ thick. It is 5% inches long before being corru Another way of regulating the starting voltage ' gated and 4% inches long after corrugating. It is by proper choice of~>the atmosphere filling the ' is wound into a coil of seven turns, 11; of an inch tube. II the atmosphere be wholly a gas, such as between ends, % inch being allowed at each end neon, the starting potential is smaller, but the for mounting.v The shield 24 has a cylinder .531 voltage drop across the arc is higher than it the inch internal diameter. The two external ?anges tube be filled with mercury vapor. By proper 10 combination of the two, any desired relation be are a’, of an inch wide. The ?at part of the cen tween the starting voltage and the arc drop can tral ?ange is 5'0! an inch wide, and the central 10 part has .062 inch internal diameter where it fits be obtained. the standard 2!. ' ' If the tube has some liquid mercury in it when cold, the heat generated within the tube when 15 energized will vaporize the mercury increasing the mercury vapor in the tube. The mercury vapor will cause a diminution in the arc drop and thus, at constant output, a diminution in the heat pro duced. The tube will soon arrive at a steady state in which the temperature is constant and thus the pressure in the tube is also constant. Thus the voltage drop and the starting potential will each be fixed. In order to disclose this invention more com pletely, I am stating here the dimensional details concerning one type of this tube which is in extensive commercial use. I do not wish to be understood as saying that this is the only type which has achieved commercial success, nor do I intend the speci?cation and claims to be lim ited by the dimensional description here given. This tube is used as a full-wave recti?er. The cathode is oxide coated and directly heated. The heating current is 6.4 amperes and is supplied with 2.5 volts. It requires 30 seconds to reach its > It will be apparent to those skilled in the. art that many modi?cations besides those here ex pressly described, can be produced. I, therefore, do not desire that the invention be limited to 1a what is here explicitly described. No limitation not required by the prior art or expressed by the claims is intended. I claim as my invention: 20 1. A space discharge device including an en velope, a cathode and a plurality of anodes, an electrostatic shield electrically continuous within the envelope separating said anodes and forming a chamber about each anode with an opening for each anode which leaves the direct line from such anode to the cathode unimpeded, said shield ex tending across all direct paths between any two anodes. , 2. A space discharge device including an en 30 velope, a cathode and a plurality of anodes, a plurality of metal cylinders, open ends on said cylinders, said anodes being respectively posi tioned within said cylinders, said cylinders con stituting electrostatic shields electrically continu working temperature when starting cold. The" ous within the envelope and crossing all direct 35 alternating voltage between the anodes may be paths between any two anodes while said open as high as 440 volts, and the average anode cur ends leave unimpeded the direct line from each rent output may be as high as 1 ampere. When anode to said cathode. an anode reaches a potential of 30 volts positive 3. A space discharge device comprising a cath with respect to the cathode, it will always have ode comprising a solid conducting body, a pair started to carry current and the arc drop for the conductive period will average about 131/2 volts. The tube is 6% inches long from the top of the part of the envelope, which is coated interiorly at 26 to the bottom of the connecting pins upon the socket, which is not shown in the drawing. It is 2%; inches in diameter. It is ?lled with argon to a pressure of 0.6 millimeter of mercury and is air of anodes, and a pair of interconnected metallic cylinders within which said anodes are respec tively positioned to form a single electrically con tinuous electrostatic shield having a portion in terposed between said anodes, said shield having two openings through which the direct lines from each anode to the cathode pass. WALTER E. BAHLS.