US2650318A - Rectifier tube and system - Google Patents

Description

Aug. 25, 1953 P. M. G. TOULON 2,650,318

RECTIFIER TUBE AND SYSTEM Filed Jan. 15, 1951 4 Sheets-Sheet 1 F] INVENTOR' IE PIERRE MARIE GABRIEL TOULON BY ma m ATTORNEY 1953" P. M. G TOULON 2,650,318

RECTIFIER TUBE AND SYSTEM Filed Jan. 13, 1951 4 Sheets-Sheet 2 5 PIERRE MARIE GABRIEL TOULON ATTORNEY Aug. 25, 1953 P. G. TOLJLON RECTIFIER TUBE AND SYSTEM Filed Jan. 15, 1951 4' Sheets-Sheet 3 .FIg.4

v INVENTOR PTER E MARIE GABRIAL TOULON ATTORNEY Aug. 25, 1953 P. M. s TOULON RECTIFIER TUBE AND SYSTEM Filed Jan. 13, 1951 4 Sheets-Shae? 4 /A L g 2|3 I44 141 N43 V no 7 INVENTOR PIERRE MARIE GABRIEL TOULON BY fi/ m ATTORNEY Patented Aug. 25, 1953 UNITED STATES PATENT OFFICE RECTIFIER TUBE AND SYSTEM PierreM. G. Toulon, New York, N. Y., assignor to Products; and Licensing Corporation, New York, N. Y., a=corporation of Delaware Application January 13, 1951, ,Serial No. 205,845

12 Claims.

The present inventionrelates generallyto new and simplified ionic-tube-structures, capable of handling'very high currents, and to-novel-arrangements for priming-or initiating the discharge of such tubes.

At the present time, a large number ofdifierent types of gaseous conduction tubes are known, some of these; specified by way of example, being phanotrons, ignitrons, thyratrons, and excitrons. In addition, polyanodic rectifiers-are well known in-the art; which operate by means of gaseous 'conductionu Tubes of the gaseous conduction type, when designed to carry very heavy currents-generally present great difiiculties of construction, and of "cooling, when arranged in accordance with prior art principles. Thereby, they'v become complicatedand costly. Additionally, relatively complexstructure 'is required for controlling the current passing through the tubes, since this generally involvescontrol of firing times of the tubes.

It is a primaryobject of the present invention to overcome the above-mentioned dilficulties, by providing a simple, economical and readily. eii'ectuated construction for gaseous-conduction tubes, and a'simple and practical method of controlling the firing of such tubes;

More specifically, the construction and operation of gaseous conduction tubes involves several difficulties. If such a tube utilizes an electron emissive cathode, difficultiesarise in providing sufficient emission from the cathode, and indisposing of the heat liberated from; the cathode. Tubes of the liquid cathode type, on the other hand, involve difficulties of firing initiation, but do not involve difficulty due to limited emission. It is essential, if a gaseous conduction device is to pass a very heavy current, that the cathode provide a very heavy emission. When'use is made of liquid cathodes, to provide high emission, an emissive cathodic spot is formed onthe surface of the liquid cathode, usually mercury. Use of a mercury cathode provides the advantage of enablin discharge of almost unlimited currents, but involves the serious problem of initiating orforming. the cathodic spot precisely at the instant desired, of localizing the cathodic spot, of condensation of mercury vapor on the walls of the tube, of the conductivity of this mercury vapor, of the relatively'slow tie-ionization time of mercury vapor, and of the formation of ultra-violet rays by the arc. The'cathodic. spot may be generated either'by tilting the tube; or by means of a mobile electrodeprovided with suitable actuating means. In either case, it-ls necessary to provide considerable accessory equipment for the tube, for the purpose of priming or forming and maintaining the cathodic spot. It follows that a solution involving mercury cathodes, while acceptable for a polyanodic tube utilizing a single cathode, may be prohibitive if a large number of separate tubes must be utilized in a circuit, and if prior art principle are followed. In the latter case, in fact, the cathodes of the tubes may require to be insulated from one another, and it is usually necessary separately to prime and maintain the cathodic spot in each of the tubes.

It is possible, in accordance with .the presently known art, to form and maintain a cathodic spot on a mercury electrode by means of a so-called ignitor electrode immersed in the mercury. However, the apparent simplification which derives from the fact that the ignitor electrode need not be moved, is compensated for by the fact that heavy current must be supplied to the ignitor electrodes, at controlled times, which involves considerable expensive circuitry, and generally in the prior art has involved use of thyratron tubes, condensers, auxiliary control tubes, and phase control devices.

Where oxide coated cathodes are utilized in tubes designed to carry heavy currents, considerable simplification of structure results, since the cathodes may be heated, while electrically isolated, by means of transformers, but the tubes present other difiiculties. Specifically, the maximum current which may be passed by the tube is quite limited, because the cathode deteriorates rapidly-if too high a current passes for even a very short time. Further, the power consumed in heating the cathode is-very considerable, of the order of ten watts per ampere of output. While the latter difiicultymay be, overcome by heat insulating the cathodes, in which case it is possible to obtain one ampere of discharge in return for one watt of: heating current, the latter solution results in considerable time lag in heatingthe cathode-before the tube becomes available for use in a circuit.

A furtherdifliculty which occurs in high power rectifier tubes involves the problem of cooling. An outer water jacket for the tube may be utilized, but this involves arather delicate design, and requires the insulation of the water conduits. Further, in mercury cathode tubes, in order-that the tube shall not fire in reverse direction, it is necessary to prevent condensation of mercury on the anodes of the tubes,-and for this purpose the anodes must be maintained at a temperature higher than the body of the tube. Graphite anodes are normally employed in such tubes, and the cleaning of such anodes, which is necessary after a definite length of service, is a lengthy, complicated and costly affair.

The droplets of mercury which are deposited on the inner walls of the tube interferes with the insulation of the tube, and provides a further difficulty in systems of this type, since it is necessary to maintain the insulators existing between the electrodes, or the structure which provides such insulation in any particular tube structure, at a temperature which is relatively high, to avoid undue condensation of mercury thereon.

Lastly the construction and suspension of control grids in mercury cathode tubes introduces serious difficulty, since the deposit of mercury on the grid can prevent its functioning. Additionally, feeding of control voltages to the grids ne-' cessitates auxiliary circuits which are complicated and costly.

It is a primary object of the present invention to provide a monoanodic tube, preferably of the mercury cathode type, which overcomes the above described difficulties.

More specifically, it is an object of the present invention to provide a high powered mercury cathode rectifier tube which may be economically fabricated, and more efficiently cooled than is possible with known constructions.

A further object of the present invention resides in the provision of a mercury cathode high power rectifier which may be readily assembled and dis-assembled.

Still a further object of the invention resides in the provision of a mercury cathode rectifier fabricated of a relatively small number of easily constructed parts.

Another object of th invention resides in the provision of a novel circuit for controlling firing of a tube of th character disclosed, and forming a subject of the present invention.

Still another object of the invention resides in the provision of a mercury cathode tube in which firing may be initiated by means of particularly simple circuits involving no firing tubes.

Another object of th invention resides in the provision of a novel circuit arrangement for connecting the novel tubes of the present invention for rectifying power derived from a three phase source, in controllable amounts, by controlling the firing times of the tubes.

The above and still further features, objects and advantages of the invention will become apparent upon consideration of the following detailed description of a tube structure embodying the invention, and of circuits for controlling firing of one or more tubes constructed and arranged in accordance with the invention, especially when taken in conjunction with the accompanying drawings, wherein:

Figure 1 is a view in longitudinal cross-section of certain elements of a gaseous conduction device, arranged in accordance with the invention,

shown separated, prior to their assembly in a completed tube;

Figure 2 is a longitudinal section of a complete .and assembled tube, constructed and arranged in accordance with the present invention;

Figure 3 is a schematic circuit diagram of a firing arrangement for a tube arranged in ac- Figure 5 is a schematic circuit diagram of a modification of the system of Figure 4.

Referring now more specifically to the drawings, reference numeral l identifies a cup shaped anode, fabricated of thin metal, such as Kovar, or other metal which may be readily de-gassed, and which forms a vacuum tight seal with glass. Anode l is sealed; at its upper open edge 2, to a glass annulus 3 which extends radially outward from the anode l. The outer wall 4 of the tube may be fabricated either of glass or of metal, but in either event is cylindrical, and is provided at its upper edge with an outwardly extending flange 5, formed of glass or the like. The inner diameter of the envelope 4 is greater than the outer diameter of the anode but the flanges 3 and 5 have substantially equal outer diameters, so that the upper surface of the flange 5 may be sealed to the under surface of the annulus 3.

A cathode is provided for the tube, in the form of a metallic cup 6, filled with mercury 1. Resting on the bottom of the cup 6 is a ring 8, which extends above the surface of the mercury l, and which is provided with apertures 8a, to enable free fiow of the mercury beyond the ring 8. The ring 8 serves to localize the cathodic spot on the surface of the mercury i, when the spot is formed. The metal of which the cup 6 is formed may be Kovar, or other metal suitable for scaling to glass. A glass ring 9 may be sealed to the upper edge of the cup 6, and to the glass ring 9 may be secured a stem Ill, having an axial aperture H through which the tube may be exhausted, and filled with suitable inert gas, such as xenon, after it has been assembled. Further secured to the glass ring 9 is a glass support I2, through which extends a lead l3, the glass [2 serving as insulation for the lead l3, and the lead l3 terminating in an electrode M, which may be in the form of an inverted cone, having its apex adjacent to but not touching the surface of the mercury pool I, axially of the latter. Secured to the under wall of the cup 6 is a further cup 15, having its open end extending downwardly, and about the cup I5 is secured a strap l6, which serves as a cathode lead for the tube. The glass ring 9 may then be secured to the cylindrical envelope 4, of the tube, by sealing if the envelope 4 is of metal, or by welding thereto if the envelope 4 is of glass. The annulus 3 may then be welded to the flange 5 to complete the enclosure for the tube.

The tube formed in the manner above described is of very light structure, and easily fabricated, and the cups and tubes of metal may be readily degassed by high frequency heating, or in other known ways.

Extending co-axially of the anode structure I is a metallic tube 20, from the outer wall of which extends a number of metallic cooling fins, as 2|, 22. Tube 20 may have substantially the same diameter as the anode I, although this is not essential, and may be open at its upper end, and there provided with an outwardly bent lip 23, while at its lower end the tube 20 may be provided with an outwardly extending flange 24, extending at right angles to the axis of the tube 20. The flange 24 may be superposed on the flange 3, being separated therefrom by means of a rubber washer or gasket 25, which provides a water tight seal.

Fitting tightly in the lip 23 may be provided .a rubber stopper 26, having an axial aperture 21 through which extends a copper tube 28. The upper end of the tube 28 is sealed by means of a lid 29 through which'extends axially, and in sealed relation, a rod 30, which is fabricated of material having a high coefficient of expansion with heat. To provide an easily accessible terminal point, the tube 28 is provided with a circling strap 3|, of metal, which firmly contacts the cylinder 28, and which is provided with a radially extending lug 32 to which cable may be readily attached. The tube 28 extends co-' axially with the cylinder to a point just within the anode I. At this point the tube 28 is bent to one side, as at 33 so that it no longer extends co-axially of the tube 20 or of the anode I, and at at least one point, 34, contacts the inner wall of the anode I. An extension 35 of the tube 23 is provided, which extends within the anode l and co-axially therewith, which is open at its lower end, as at 36, and which is provided with a passage at its upper end as at 3?. The rod extends through an opening in the bend 33 of the tube 28, and is in sliding relation thereto, and extends entirely through the tube 35. The rod 30, at its lower end, is provided with a valve 31, which is capable, while the rod 30 is cold, of closing or almost closing the lower end 36 of the tube 35. As the rod 30 heats up, since the rod 30 is fixed at its upper end to the lid or closure 29, the lower end carrying the valve 3'! moves downwardly, unmasking the opening of the tube 35; The valve 31, and the rod 33, provide I accordingly a thermostatically controlled valve, capable of controlling flow of liquid in extension 35.

The anode I and the tube 23 are filled with cooling liquid, which, moreover, fills the tube extension 35, via the opening provided by the valve 31, and fills the tube '28 via apertures 33, which are located just under the stopper 25. When heat is supplied to-the cooling fluid, due to passage of current to the anode l, the cooling fluid passes upwardly by convection, as indicated by the arrows 39, 40, within the tube 28, passes through the openings 38 and then downwardly between the inner wall of the cylinder 20 and the outer wall of the tube 28, through the interior of the tube extension 35, as indicated by the arrows 40, and out through the space between the lower edge 36 of the tube 35 and the valve 31, as indicated by the arrows 41.

In order to assure contact between the tube 35 and the anode I there is provided at least one fixed spring, as 42, which radiates from the tube 35 to the inner walls of the anode l in the form of a spiral. Thereby firm contact is made between the anode I and the tube 28, and hence the terminal lug 32.

In order to provide cooling of the Wall 4 of the tube there is provided an encircling metal cylinder 45, having a greater diameter internally than does the wall 4 externally, so that a space for cooling liquid is provided therebetween. The encircling cylinder is provided at its upper end with inwardly extending flange 45, designed to be secured to the underside of the flange 5 of the wall 4, and being separated therefrom by means of a rubber gasket 41, which provides a water tight seal. The lower edge of the encircling cylinder-45 flares outwardly, as at 48, and a sealing ring 49 of trapezoidal cross section is wedged into the space between the outwardly flaring rim 48, and the ring 9, by means of a metal ring 50 located under the sealing ring 49. Pressure is exerted between the flange 24 of the cylinder 29 and the metal ring 50 by means of a plurality of draw bolts, as 5|, which may be tightened by wing nuts as 52, and when tightened, the draw bolts 5| effectively seal the gasket 25, the gasket 41 and the ring 49, thereby securing asone unit the various components of the tube structure. Cooling liquid may be supplied internally of the encircling cylinder 45 by means of an aperture 53 provided therein, and the liquid, after having absorbed heat from the wal1 4, may be withdrawn via a further aperture 54 in the encircling cylinder 45.

Reference is now made particularly to Figure 3 of the accompanying drawings wherein is illustrated a schematic circuit diagram of an arrangement utilized for initiating a cathodic spot on the mercury cathode l of the tube illustrated in Figure 2 of the accompanying drawings.

In the schematic circuit diagram of Figure 3 of the accompanying drawings is shown a condenser 60, in series with an inductance 6|, the junction point betweenthe condenser 60 and the inductance 6| being designated 62, and the free end 53 of the condenser 60 being connected via lead 64 to the cathode 1, while the free terminal 55 of the inductance 6| is connected via lead 66 to the control electrode [4. Between the terminal 62 and the terminal 65 are connected in series a condenser 61, secondary winding 68 of an induction coil 69, and a spark gap 10. The primary winding H of the induction coil 69 is connected in series with a source of' current 12, designated as a battery for purposes of convenience, and with a pair of breaker points 13. Accordingly, when the breaker points 33 are closed current flows in the primary winding H, and when the breaker points 73 are opened rapidly, current now in the primary winding H is interrupted, resulting-in the induction of a high voltage in the secondary winding 58. The voltage induced in the secondary winding 68 is sufficiently great toresult in formation of a spark in the spark gap 10, causing a sudden flow of current in the inductance 6!, and thereby generatesa high voltage between the control electrode [4- and the cathode I, resulting in an-ionization of the rarified gas which is provided in the interior of the tube. This rarified gas may be a gas such as xenon, and additionally, there may be present in the tube mercury vapor arising from the cathode l. The spark which occurs between the control electrode l4 and the cathode 1 is said to pilot the priming of the arc in the tube, or to initiateits formation, and by suitably timing the opening of the breaker points IE3 with respect to the phase of a voltage which may be applied to the anode of the tube, the time of current flow through the tube may be controlled.

While a spark is generated between the control electrode [4 and the cathode 1, the tube cannot be fired by this spark alone, due to the relatively small current which exists in this spark. To supplement the current due to spark formation, the condenser 53, which may be of considerable size, is charged heavily through aresistance 15 and a secondary winding i a transformer 11, having a primary winding '18. The condenser 60 is accordingly charged with alternating current. However, the phase of this alternating current may be so arranged that the terminal 62 is highly positive at the time when the spark is caused to pass between the control'electrode l4 and the cathode l. The passage of "his spark completes a circuit for the condenser 60, or provides a low impedance discharge path therefor, and the condenser accordingly discharges, via the-inductance 3|, providing sufiiciently heavy current to volatilize the mercury of the cathode I, and sufficient ionization to fire the tube, i. e., to effect passage of current from the anode to the cathode of the tube, provided the anode is positive.

In order that the direction and magnitude of the charge in the condenser 60 may be suitable, at the time when the breaker points I3 are opened, the breaker points I3 may be actuated by an electromagnet 80, energized from alternating current supply terminals 8I, and the primary winding 18 of the transformer 11 may be supplied with voltage from the same terminals 8|, the circuit constants and delay times of the mechanical breaker points I3 being properly selected.

The condenser 61 is not essential if only a single tube is to be controlled, but may become necessary to provide D.-C. blocking in a system utilizing a plurality of tubes. The condenser identified by the reference numeral 82 may represent the inherent capacity of the secondary winding 08 of the transformer 09, but in some cases it may be desirable to supplement this inherent capacity by an additional condenser, to raise the total voltage developed across the secondary winding 68.

Reference is now made to Figure 4 of the accompanying drawings, which provides a schematic circuit diagram of a rectifying system employing three pairs of tubes connected in known fashion to a three phase line, to supply rectifled current to a load circuit. The tubes utilized in the system of Figure 4 may correspond with the structure which is illustrated in Figure 2 of the accompanying drawings, and while the generation of priming current for the control electrodes of the tubes employ the principles of the circuit illustrated in Figure 3 of the accompanying drawings, it is found preferable to eliminate mechanically actuated breaker points, and to substitute purely electrical devices for generating the necessary pilot sparks between the control electrodes and the cathodes of the tubes.

In the system of Figure 4 the reference numeral I represents a three phase line, and the reference numeral IOI represents a load circuit to which rectified current is to be supplied from the three phase line I00. Three gaseous conduction devices I02, I03 and I04 are connected with their anodes to the separate phases of the three phase line, their cathodes being connected together to a lead I05, which represents then the positive D.-C. terminal of the system, and which may be connected accordingly to the positive terminal of the load IOI. If the separate lines of the three phase line I00 be identified by the reference letters A, B and C, the tubes I02, I03 and I04 may have their anodes connected to the lines A, B and C respectively. A further gaseous conduction device I00 may have its cathode connected to the line C, a gaseous conduction device I01 may have its cathode connected to the line B, and a gaseous conduction device I08 may have its cathode connected to the line A. The anodes of the gaseous conduction devices I06, I01, I08 are connected together by means of a lead I09, which then forms the negative terminal of the rectifying system, and may be connected to the negative terminal of the load I0 I. It follows that, as between pairs of lines of the three phase source I00 are connected pairs of tubes in series with the load. Since the separate lines A, B and C reach their maximum voltage values in a positive direction at time separations equal to 120 of the source frequency, the tube pairs conduct in sequence at time intervals, resulting in a fairly steady current in the load NH.

The mode of connection of the gaseous conduction devices to the three phase line and to the load is conventional per se. The present invention resides in the system employed for eifecting controlled firing of the tubes.

In order to effect controlled firing of the gaseous conduction devices, I02--I04, IDS-40B, periodic voltage impulses are generated, by means of a device H0, at 120 intervals as measured by the frequency of the three phase line. These voltage impulses, further, may be delayed or advanced in phase, with respect to the phase of the source, and the times of occurrence of these voltage impulses determines the times of firing of the gaseous conduction devices, I02, I03, I04, I06, I01, I08.

The device I I0 comprises a thyratron tube I I I, having an anode II2, a control electrode H3 and a cathode 0. Voltage is supplied to the anode II2 through a rectifier H5, supplied from all three phases A, B and C' and of source I00 simultaneously, the rectifier II5 feeding the anode II2 via a resistance H6. The cathode II4 of the thyratron III is connected back to the three phase line via three rectifiers II'I, poled oppositely to the rectifiers II5, to enable current flow from the three phase line through the rectifier II5 through the resistance N0, the thyratron III and from anode II2 to cathode H4, and back to the three phase line via the rectifier II'I.

Connected between anode II2 and cathode II4 of thyratron III, is a primary winding II8 of a transformer II9, in series with a condenser I20. Bias voltage for the control electrode II3 of the thyratron I II is supplied via a conventional rectifier system IZI, which derives power from one phase of the three phase line I00, and which supplies voltage across an output resistance I22. The control electrode H3 is connected via an adjustable tap I23 to the resistance I22, so that the total D.-C. bias voltage on the control electrode I I3 may be selectively varied. In series between the control electrode II3 and the tap I23 is the secondary winding I24 of a transformer I25, and a voltage limiting resistance I26. The primary winding I27 of the transformer I25 is connected between the cathode IM and the output terminal of the rectifier I I5, via a condenser I30, and to the low voltage terminal of the resistance H6, via a further condenser I20.

Since the voltage occurring at each end of the resistance H0 is not filtered, it contains pulsations at six times the frequency of the three phase line I00 and these pulsations are transferred to the control electrode I26, in series with the D.-C. bias impressed thereon from the resistance I22 forming the output load of the rectifier I2I. The times of these pulsations determine then times when the potential of control electrode II3 of the thyratron III becomes more positive than normal, and thus define firing times for the thyratron III.

In operation, the condenser I20 is charged via the rectifiers H5 and III, the thyratron III being maintained non-conductive by the bias rectifier I2I, and the charging time of the condenser !20 via the resistance H6 is so set that the condenser contains a very considerable charge at the time when a pulsation is applied to the control electrode II3 to render the thyratron III conductive. At this instant the condenser I20 discharges through the thyratron.

providing'a sharp pulseof current in the primary winding II 8 of the transformer II3. Thereby a high voltage pulse is generated in the secondary winding I30 of the transformer H9. The high voltage pulses generated in the secondary winding I30 occur siX times during each cycle of voltage in the three phase line I 00, at 120 phase intervals, and determinethe firing times of the gaseous conduction devices I02, I03, I04, I06, I01, I08. These firing times may be varied by adjusting the bias on the control electrode II3, by varying the position of the slider I23, in accordance with principles which are well known Der se.

The voltage pulses available across the secondary winding I30 of the transformer H are applied between two leads or bus-bars KM and I32. Directly connected to the bus-bar I3I are six spark terminals I33, I34, I35, I36, I37 and I38, which, as will appear hereinafter, are allocated respectively to the gaseous conduction devices I02, I03, I04, I01, I08. Similar spark gap terminals I39, I40, I4-I, I42, I43 and I44 are connected to the bus I32, but via primary windings I45, I46, I47, I48,,I49 :and 550, respectively. Accordingly, the voltage supplied by the secondary winding I30 is applied simultaneously and in identical phase to each pair of opposed spark gaps, as I33, I39, or I34, I40, etc. It is desired, however, that these spark gaps break down in time sequence, at 120 time intervals, since the spark gaps control the gaseous conduction devices respectively, and since, therefore, each spark gap must break down at the proper time to accomplish firing of the proper one of the gaseous conduction devices.

In order to accomplish controlled break down of the spark gaps thereis provided intermediate each pair of spark gap terminals as I33, I39 or I34, I40, etc., a metallic ring, these rings being identified, respectively, by the reference numerals I5I, I52, I53, I54, I55, I56. The voltage applied between any spark gap terminal pair, as I33, I39, or I34, I40, etc., and the spacing of the terminal pairs, is such that the gaps will not break down unless the associated ring is at a suitable potential for this purpose. The function of these rings is to modify the voltage gradient existing between any terminal pair in such way that break-down may occur. To this end there are applied to the rings I5I to I55, inclusive, voltages from a transformer I00, which is energized from the three phase line I00, and which applies to the rings voltages separated by 120. Break-down can occur only while a ring has a voltage adjacent to a maximum value, as available from thetransformer I60.

Accordingly, the transformer I60-applies voltages to the rings I5II56, in sequence, which controls the sequence of break-down of the spark gaps. The actual timing of each breakdown is, however, in response to an impulse provided by the secondary winding I30, so that the actual timing of the break-down may be COII'? trolled over a' considerable range of values, by adjustment of the slider I23.

When any spark gap breaks down the associated primary winding of transformers I45 to I50, inclusive, conduct current. Thereby voltages are induced in the corresponding secondary windings, which are applied between cathode and control electrode of the associated gaseous conduction devices. The spark gap devices accordingly perform the same function in the system of Figure 4 as does the mechanically operated circuit maker and breaker device utilized in the system of Figure 3. It will be clear, therefore, that in the system of Figure 4 a mechanically operated spark generator may be utilized in place of the spark generator disclosed. This is, however, undesirable, and the system of Figure 4 being preferable, because no moving parts are involved in the latter, the system being entirely electrostatically controlled.

The spark discharges provided by the transformers I45 to I50, inclusive, are not sufiicient, however, of themselves, to effect firing of the gaseous conduction devices I02, I03, I04, I06, I07, I08, but each serves merely to provide a discharge path for a condenser, which discharges a heavy current between the control electrode and cathode of the gaseous conduction device, and it is the condenser discharge which actually accomplishes firing of the tubes.

In order to provide a condenser discharge between control electrode and cathode of each of the gaseous conduction devices of the present system, there are provided six condensers IE! to I66, inclusive, each of which is connected in series with a resistance, as I61 to I72, inclusive, and each condenser and associated resistance, as I6I, I61, or I62, I68, etc., is connected across one output phase of a transformer I I5 which is energized from the three phase line I00, and which supplies, across six separate output or secondary windings, voltages separated by Accordingly, the condensers IBI to I66, inclusive, are being continually supplied with alternating current voltage from the transformer I15, but at 120 separation of phase in the separate condensers.

Each one of the condensers, as I6! to I06, inelusive, is connected through a secondary winding of one of the transformers I45 to I 50, inclusive, between control electrode and cathode of one of the ionic discharge devices, as I02 to I04, I06 to I08. For example, a circuit may be traced from condenser I 6i through the secondary winding of transformer I45, via lead lit, to the control electrode of gaseous conduction device I02, and from the cathode of that device back via lead IT; to the other side of the condenser I6I. While the voltages available across the condensers are continuously being applied between control electrodes and cathodes of the gaseous conduction devices, their magnitudes are so selected that the gaseous conduction devices do not fire in response thereto. When, however, a pilot spark is caused to occur in any gaseous conduction device, a low impedance path is thereby provided between control electrode and cathode of the associated tube, and thereby a low impedance discharge path for the associated condenser. It follows that the condensers discharge only in response to the pilot sparks. The pilot sparks are so timed, and the condensers are so driven, that at the time a pilot spark occurs considerable voltage exists across the associated condenser, so that a very heavy current discharge then appears in the gaseous conduction device. Firing occurs, in response to that heavy current. Once firing has been initiated the anode to cathode voltage of the tube maintains the arc, and current flows to the load I0 I.

Reference is now made to the system of Figure 5, which representsa modification of the system of Figure 4, which, because of the mode of connection of the rectifying gaseous conduction devices in the system, permits use of a simpler firing control arrangement than is possible in Figure 4. Specifically, in the system of Figure 5 the cathodes of all the aseous conduction devices are at a comon potential and inter-connected, which eliminates the need for circuit isolation, as provided by the transformers M5 to I50, inclusive, of the system of Figure 4.

Referring now more specifically to the system of Figure 5, the three phase line I supplies energy to a transformer 200, which is so arranged that its six windings provide voltages 120 out of phase at the frequency of the three phase source. The common point of the windings 200 is connected to the negative terminal of load WI, and the remaining terminals of the windings of the transformer 2% are connected to the anodes, respectively, of the gaseous conduction devices I02, I03, I04, I06, I01, I08. The cathodes of the gaseous conduction devices are connected together and to the positive terminal of the load IIJI. The arrangement of the transformer 200 and the associated gaseous conduction devices is, per se, well known, and forms no part of the present invention, which is, on the contrary, directed to the firing control system for the tubes.

In accordance with the system of Figure there is provided a pulse generator III), which corresponds with the pulse generator IIO illustrated schematically in Figure 4 of the drawings. As in the system of Figure 4 a transformer I00 supplies 120 phase separated voltages to rings I5I to I56 inclusive, which control the order in which the spark gap pairs, as I33, I39 or I34, I40, etc. break down. Voltage pulses from the source I I0 are applied in common to bus I3I and thence to spark terminals I33 to I38, inclusive. The remainin terminal of the voltage pulse source I I0 is applied to a corresponding terminal of each of the condensers 202, 203, i, 205, 206 and 201. The remaining terminals of these condensers are connected, respectively, to one terminal of each of windings 208, 203, 2I0, ZI I, 2I2 and 2I3. The remaining terminals of these windings are connected, respectively, to the remaining spark gap terminals I39 to I44.

Accordingly, when any spark gap pair breaks down current flows through the associated condenser and coil. For example, should the spark gap pair I33 to I39 break down a circuit will be completed from common bus I3I to terminal I39, coil 2G8, condenser 20?, common line 20I, back to the voltage pulse generator III).

Accordingly, break-down of any spark gap pair is accompanied by current flow in the associated coil, and therefore by the generation of a relatively high voltage across the coil. The voltage available across each of the coils 208 to 2I3, inclusive, is applied via one of condensers 202 to 2251, respectively, between control electrode and cathode of the gaseous conduction devices I02, I03, I04, I86, I81, I08, respectively. Thereby each passage of a spark gap between one of the spark gap terminals pairs, as I33, I39, or I3 I, I40, etc., results in creation of a pilot spark in the associated one of the gaseous conduction devices, as I02, I03, etc.

The condensers 202, to 201, respectively, are charged with alternating current, by means of the transformer I75, and the phase of the current in the separate condensers are separated by 120. The timing of condenser charging is so arranged that at the time a current flow from one of the coils 208-2I3, respectively, passes through the associated condenser, a considerable voltage exists across that condenser, deriving from the transformer I15. Passage of the pilot spark in the gaseous conduction device provides a low impedance discharge path in the device for the condenser, which accordingly discharges, in series with the coil. Tracing through the discharge path for the condenser, 202, taken by way of example, it will be clear that this condenser may discharge over lead 202, through winding 2I3, from control electrode to cathode of gaseous conduction device I08, and back to the other side of the condenser 202.

Accordingly, whenever a pilot spark is generated in one of the gaseous conduction devices I02 to I04, I06 to I08, it is accompanied by discharge of a condenser, so that a heavy transient current fiows between control electrode and cathode, resulting in firing of the tube.

In summary, it will be clear that I have provided a novel gaseous conduction device, which may be very readily fabricated, which possesses a relatively low internal volume so that it may be readily evacuated, and that the cooling facilities for the tube may be readily disassociated from the tube proper, whereby if the latter burns out a considerable portion of the equipment may be salvaged. Furthermore, anode cooling and envelope cooling are accomplished by separate fluid flows, so that the envelope itself may be maintained at a sufiiciently high temperature to assure that mercury droplets will not collect thereon, while the anode itself may be cooled to any convenient and desired temperature, which may be automatically controlled by structure inherent in the cooling system.

The specific tubes disclosed may be utilized in novel circuits, as illustrated in Figures 3 to 5, inclusive, and may be fired by arrangements which do not include movable electrodes or firing tubes, as is common in the prior art, and which are controlled electrostatically and without the expenditure of large amounts of energy. Two specific arrangements are shown for rectifying current deriving from a three phase line. At the same time, in accordance with principles well understood in the art, by proper timing of the firing of the tubes, the voltage provided by the three phase line may be changed in frequency, instead of being rectified, and other important functions in the art may be accomplished by employing tube firing systems arranged in accordance with the basic concepts of the present invention.

While I have described and illustrated specific forms of the invention it will be clear that variations thereof may be resorted to without departing from the true scope of the invention as defined in the appended claims.

What I claim and desire to secure by Letters Patent of the United States is:

1. A gaseous conduction device, comprising, a cathode, an anode, a container for supporting said cathode and anode, said container comprising two separable parts respectively supporting said anode and said cathode, each of said parts having an externally extending glass flange for sealing the parts to one another, said anode consisting of a hollow receptacle extending internally of said container, said receptacle filled with cooling liquid.

2. The gaseous conduction device of claim 1 wherein said separable parts are nested one within the other, said cathode comprising an electrically conducting cup containing mercury, said cup having a rim sealed to the lower of said nested parts, a rod of insulating material secured to said lower part and extending over said mercury, a control electrode, a lead extending through and beyond said rod of insulating material, said control electrode secured to and supported by said lead adjacent its point of extension beyond said rod of insulating material.

3. A gaseous conduction device, comprising, a tube of insulating material having a lower edge and an upper edge, a hollow cylindrical anode having a closed bottom and an open top, a first flange of insulating material for suspending said open top in insulated and sealed relation from said upper edge, a hollow cylindrical cathode container having an open top defined by an upper rim and having a closed bottom, a, quantity of mercury in said cathode container, a second flange of insulating material for suspending said upper rim of said cathode container from said lower edge of said tube in sealed relation.

4. The combination in accordance with claim 3 wherein is further provided means for supplying a flow of cooling liquid to and from internally of said hollow cylindrical anode.

5. A gaseous conduction device comprising, a ring of insulating material, a hollow cylindrical cathode container having an open top defined by an upper edge and having a closed bottom, means for sealedly securing said upper edge in said ring, a tube having an upper edge and a lower edge, means for sealing said lower edge of said tube to said ring, a hollow cylindrical anode having an open top defined by an edge and a closed bottom, and means for insulatedly and sealedly securing said edge of said anode to said upper edge of said tube, whereby said anode extends internally of said tube.

6. A gaseous conduction device, comprising, a container having internally thereof an anode, a cathode and a control electrode, a cooling system for said container comprising a cooling structure and anode lead, means for detachably securing said cooling structure and anode lead to said container, said anode comprising a concave structure extending internally of said container, said anode lead contacting said anode and comprising a pipe structure for conveying cooling fluid to and from said anode.

7. A gaseous conduction device comprising a first container portion having a first flange, a hollow receptacle anode supported by said first container portion, a second container portion having a second flange, a cathode supported by said second container portion, said first and second flanges being of substantially the same diameter and being removably sealed to one another, cooling liquid within said hollow anode.

and control means within said hollow anode for varying the flow of said liquid.

8. The device of claim 7 in which said control device comprises a tube extending into said liquid within said hollow anode, a rod having a variable temperature coefficient within said tube, and a valve device fixed to the end of said rod adjacent one end of said tube.

9. A gaseous conduction device comprising a first portion having a cylindrical receptacle anode sealed at its upper edge to a first flange of insulating material, a second portion comprising a cylindrical wall of insulating material coaxial with said anode and supporting a mercury pool cathode coaxially with said anode, said cylindrical wall having a second flange of insulating material at its upper edge adapted to be sealed to said first flange.

10. The device of claim 9 including a first cooling mechanism removably clamped to said device said first cooling device comprising a cylindrical member above said anode, cooling liquid within said cylindrical member and the outer surface of said anode, a tube extending from said cylindrical member into the hollow of said anode, a rod within said tube extending within the hollow of said anode and affixed to one end of said tube, and valve means fastened to said rod adjacent the other end of said tube.

11. The device of claim 10 in which said tube defines openings adjacent its upper end, said cooling liquid passing by convection through the openings in said tube, said valve means defining a variable opening at the lower end of said tube to control the flow of liquid therethrough.

12. The device of claim 9 including a first cooling mechanism above said first portion and extending into said cylindrical anode, and a second cooling mechanism surrounding said cylindrical wall.

PIERRE M. G. TOULON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,262,492 Hewitt Apr. 9, 1918 1,550,203 Burstyn Aug. 18, 1925 1,757,605 Ulrey May 6, 1930 2,201,966 Dawson May 21, 1940 2,298,210 Gulliksen Oct. 6, 1942 2,330,768 White Sept. 28, 1943 2,420,829 Marshall May 20, 1947 2,431,153 White Nov. 18, 1947 2,438,179 Mason Mar. 23, 1943 2,445,549 Wittenberg June 20, 1948 2,484,565 Herskind et a1 Oct. 11, 1949

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