US2179302A - Vapor electric device - Google Patents

Description

Nov. 7, 1939. H. A. RosE WQLSGZ VAPOR ELECTRIC DEVICE Filed July 9, 1938 5 Sheets-Sheet l WITNl-:ssEs: Fig- INVENTO'R Herbert A Bose. 677,60. fw Lig/y, Lam/w;

ATTORNEY NOV 7 1939 HA A. ROSE. 2,179,302

VAPOR ELECTRIC DEVICE Filed July 9, 1938 3 Sheets-Sheefl 2 WITNEssEs: INVENTOR @MJL Tm Herbert/1. Bose.

6%@ Lf d JM ATTORNEY Nov. 7, 1939. H. A. Rosa "2,179,302

VAPOR ELECTRIC DEVICE Filed July 9, 1938 5 Sheets-Sheet 3 fam@ i l l l I g E i l g I Figi 6.

WITNESSES; INVENTOR I Herbert Al'ose. BY @i I ,YM

ATTORNEY Patented Nov. 7, 1939 UNITED STATES PATENT OFFICE VAPOR ELECTRIC DEVICE East Ilittslmlrglr,A Pa.,

Sylvania a corporation of Penn- Application July 9, 1938, Serial No. 218,340

Claims.

My invention relates to a vapor electric device and particularly to vapor condensers for a makealive type converter.

In the operation of vapor-electric devices such as rectiers, having pool type cathodes, and particularly those of the make-alive type, large amounts of mercury vapor are projected from the cathode during the current conducting portion of the cycle. One of the principal diculties with make-alive converters of the more conventional design is due to the inability of the condensing vapor density exists even after current zero. The

difculty is manifest in an increase in arc back rate.

It has long been recognized as desirable to con-` dense the vapor as nearly` in phase with the decay of current at the `end of the current conducting period as is possible in order to eliminate dangers of arc backs or other faults during the non-conducting portion of the cycle.

Many arrangements have been used to accomplish this result, most of which have exposed a cooled surface to the region of the arc discharge, depending upon this surface to accommodate or substantially instantaneously condense any mercury vapor which comes in contact with it. Such i schemes have, in general, resulted in some improvement in operation. However, the degree has not been sufiiciently satisfactory, the principal reason being that suflicient and simultaneous emphasis has not been placed on the funda- `mental factors relating to methods for rapidly reducing the vapor density at the termination of the conducting period.

Experiments by various physicists have shown that, in general, a vapor is not condensed with one hundred percent efficiency on cooled surfaces. In other words, a molecule does not necessarily condense on the first impact it makes with the cooled or condensing surface. In fact, some surfaces may require on the average many hundreds of impacts or collisions before condensation takes place. Dirty surfaces, in general, accommodate or condense the vapor much less quickly or eniciently than `do clean surfaces.

In arc discharge devices it is practice to maintain all surfaces as clean as is possible. However, cbntamination is frequently present to such a degrec that the condensing efficiency per unit area of vapor condensing surface is greatly impaired. Realizing these conditions, I propose to improve (Cl. Z50-27.5)

the operation of electricdischarge devices and particularly those of the make-alive type, by introducing large amounts of properly proportioned condensing area in the path normally taken by the expanding vapor and to dispose the individual elements of this area in such way that even though the surface has comparatively poor accommodationlfor the Vapor per unit area, very fast condensation on the whole will be effected by these additional means. Condensation will by these means be made to occur substantially in phase with the current at all times, but particu larly' at the end of the conducting portion of the cycle.

In apparatus according to my invention, I accomplish this by providing a cooling element, preferably in the form of a nest of cooling coils directly exposed to and preferably directly above the active surface of the cathode area, and dispose the anode in suchv manner that the ions or current flow between the cathode and anode is substantially across or at right angles to the normal direction of vapor flow. In this way, the vapor stream enters the condenser directly and is condensed either immediately or after collision with a number of the condensing surfaces.

As is well known, the individual atoms in a stream of vapor travel helter-skelter in a Inanner individual to their energies. However, because of the proximity of the cooling surface to the active cathode area, the general vapor flow is substantially directly from the cathode surface to the cooling elements. In order to permit the vapor to flow directly into the cooling elements with lowest impedance, it is desirable to space the individual cooling elements so as to take advantage of the helter-skelter motions. This is accomplished by the large area and open construction of the condenser.

Recent studies by means of the memnoscope have shown that arc backs, or backres, as they are sometimes called, may occur at any time during an inverse half cycle instead of substantially at the end of transition time, as has heretofore been supposed. I believe that the cause of some, if not all, of the backres occurring at other Ythan the transition time is caused either by bombardment of the anode surface by condensed vapor or by foreign particles driven from the cathode surface and possibly aggravated by Brownian movement of infinitesimally small par.. ticles. I believe these particles in striking the anode produce conditions there which under the application of inverse potential results in the production of a cathode spot on the anode in much the same way as a make-alive electrode produces a cathode spot on a mercury surface when subjected to electric potential. To mitigate the bombardment, I propose to intel-pose a shield 5 member between the cathode surface and the anode surface so that particles traveling in a straight line from the anode to the cathode will intersect this shield surface.

In the preferred embodiment of my invention,

10 the shield is provided as a cylindrical container substantially enclosing the sides and top of the condenser element, leaving the condenser open only substantially to the cathode surface. If desired, the shield may be insulated from the con- 15 denser or even made or" insulating material to prevent intermediate attachment of the arc to the shield or the condensing element.

It is, accordingly, an object of my invention to provide a vapor-electric device having a cooling 20 element of large surface directly exposed to the active cathode surface.

It is a further object of my invention to provide a cooling element which will condense the evaporated cathode material substantially in 25 phase with the decay of current at the end of the conducting interval.

It is a further object of my invention to provide a vapor-electric device in which the ion currents are substantially transverse of the vapor 30 current between the active cathode area and the condensing element.

It is a further object of my invention to provide a shield to prevent impacts of particles driven from the cathode surface on to the anode sur- 35 face.

It is a further object of my invention to provide means for preventing intermediate attachment of the arc stream to the condensing or p shielding elements.

40 Other objects and advantages of my invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Figure 1 is a schematic illustration of a vaporelectric valve embodying my invention;

Fig. 2 is a similar view of a modication of a similar valve;

Fig. 3 is a similar modication showing a valve adapted for high voltage discharges;

Fig. 4 is a schematic illustration showing another method of securing cross flow of the electric current stream and the vapor stream;

Fig. 5 is a schematic illustration showing the manner of condensing vapor on a simple cooled surface; and

Fig. 6 is an illustration of the manner of condensing the cathode vapor in my improved condensing element.

In the illustrated embodiment of my invention according to Figure 1, the electron valve or vapor-electric converter comprises a container l preferably constructed of metal and being highly evacuated. A vapor producing element illustrated as a reconstructing cathode 2, which may be composed of mercury, gallium or other suitable material, occupies all or at least the major portion of the bottom of the container I. The side walls of the container I may be cooled by any suitable means herein illustrated as cooling coils 3 attached to the outer surface of the container I. Cooperating with the cathode 2 is a suitable anode Il herein illustrated as an annular ring disposed laterally of the active portion of the cathode surface. A suitable make-alive electrode 6, that is, an electrode composed of suitable high resistance or substantially non-conducting material capable of reducing the negative reluctance of the cathode for creating a cathode spot thereon upon the passage of electric current from the electrode to the cathode, is disposed in permanent contact with the cathode surface, at least during normal operation of the device. Directly above the active cathode surface is my cooling element I9, herein illustrated as being composed of a large number of coils so arranged as to have an opening for allowing access of vapor to the interior of the coil and the individual coils being so arranged that vapor reflected from or reevaporated from any coil is so directed as to immediately thereafter contact with the same or another portion of the cooling element IE. This multiplicity of cooling surfaces substantially instantly condenses the evaporated cathode material regardless of any impairment of the accommodation coeiicient of the individual surface area for any reason. In the embodiment according to Fig, 1, I have shown the anode 4 as being supported at a plurality of points on its periphery, one or more of these points being electrical connectors II passing in insulated relation to the evacuated container I.

In the modification according to Fig. 2, I have shown my anode 4 having a single point of support II with the make-alive electrode 6 being brought in through the bottom of the container I and suitably insulated from the cathode 2 through which it passes. As in Fig. l, the cooling element I comprises a nest of cooling coils directly exposed to the active cathode surface. In order to prevent direct impingement on the anode 4 by particles driven off from the cathode 2, a suitable shield I herein shown as a cylindrical element closed at the top is placed around the condensing element IU. The bottom of the shield I5 is so positioned, with respect to the active anode face and a barrier I5 defining the active cathode surface, that a straight line between the active cathode surface and the anode surface will be intercepted by the shield I5. I'f desired, this shield I5 may be insulated from the condensing element by suitable insulators or the shield itself may be made of suitable insulating material so that the arc between the cathode 2 and anode 4 cannot atttach to the shield element I5.

In the modification according to Fig. 3, the anode 20 has been placed above the cooling element I0 and at a material distance from the cathode 2 in order to adapt the device for high voltage discharges. A suitable shield 2I is placed at least across the top of the condensing element Ill so that the arc discharge from the anode 2t to the cathode 2 must necessarily pass around the condensing element Ill and thus enter the cathode 2 at a direction transverse of the flow of vaporized cathode material. Because of the excessive distance between the anode 29 and the cathode 2, an auxiliary exciting electrode 22 is preferably introduced between the cathode 29 and the anode 2 so that after the exciting of the device by the make-alive electrode 6, an arc will be struck to the auxiliary exciting electrode 22 to provide sucient ionization to permit ready pick-up of the arc between the main anode 29 and cathode 2. Any suitable means (not shown) may be utilized for maintaining the auxiliary electrode 22 inactive during the non-conducting period in the valve.

In the modification according to Fig. 4, a nonsymmetrical form of arrangement is illustrated the cathode spot being strucklat -oneend of the cathode 2 in the container lv while the anode 25 is placed at the other end laterally of the cathode surface and a suitable shieldn26 interposed ticles passing in a straight linefrom the cathode 2 to the `anode 25; `That portion ofthe container l directly above the cathode 2 is again provided with any suitable multi-surface condenser lll. i l

The schematic illustration according to Fig. 5 illustrates the manner of condensing evaporated material on the usual cooled surface, the molecules 30 passing from the cathode surface 2 directly to the cooled surface 3i.` However, in this arrangement, only the layer of molecules adjacent the cooled surface has a chance to be condensed and the molecules of this layer must either be condensed or reflected back into the converter before any further molecules have a chance to be condensed. Because of the impediment of condensation by the molecules adjacent to the condensing surface, it has been found that there is considerable time lag between the decay of current at the end of the conducting portion of the cycles and the condensation of the evaporated cathode material. With my improved condensing element, as shown in Fig. 6, the very large condensing area is provided and is so broken up that a major portion of the evaporated cathode material will impinge directly upon some portion of the condensing surface I0 and if reflected or re-evaporated from this condensing surface will immediately come in contact with another condensing area as shown at lill so that even though `the accommodation coemcient of any particular area of the condenser I0 may be small, the arrangement is'such that many collisions take place in` a short time so that condensation of the evaporated material is substantially in phase with the decay of current at the end of the conducting portion of the cycle.V

While for purposes of illustration. I have shown and described specific modiiications of my invention, it will be apparent that many changes and modifications can be made therein without departing from the true spirit of my invention or the scope of the appended claims.

I claim as my invention:

l. A vapor-electric device comprising an evacuated container, an annular anode in said container, a vaporizable cathode in said container,

a make-alive electrode in contact with said cathode during normal operation of said device, means for retaining the cathode spot on a predetermined portion of the cathode surface, a nest of cooling coils directly above the active cathode surface and extending through the opening in the annular anode, and a metallic shield enclosing the nest of cooling coils on all sides except that directly exposed to the cathode.

2. A vapor-electric device comprising an evacuated container, an annular anode in said container, a` vaporizable cathode in said container, a make-alive electrode in contact with said cathode during normal operation of said device, means for retaining the cathode spot on a predetermined portion of the cathode surface, a nest of cooling coils directly above the active cathode surface and extending through the opening in the annular anode, and a metallic shield i enclosing the nest of cooling coils on all sides shield extending to a point such that a straight line passing over the spot retaining means and under `the shield will not intersect the anode surface.

3. `An electric valve device comprising a metallic container, a vaporizable cathode in said container, means for periodically. initiating a cathode spot on said cathode, a barrier for restricting the cathode spot to a predetermined portion of the cathode surface, a nest of cooling coilsdirectly above the cathode and extending beyond the cathode spot barrier, a single anode displaced laterally of said cathode and said nest of `cooling coils and a shield for intercepting material which tends to pass directly between the cathode and the anode.

14. A vapor electric device comprising a` metallic container, a pool of cathode material covering at least a portion of the bottom of the con tainer, an electrode of resistance material in contact with the cathode pool during normal operation of the device, a baiile for restricting the cathode spot to a predetermined area of the cathode pool, an annular anode having an opening greater in extent than the active cathode area, a nest of cooling coils extending through the opening in said annular anode and directly opposed to the active cathode area.

5. A vapor electric device comprising a metallic container, a pool of cathode material covering at least a portion of the bottom of the container, an electrode of resistance material in contact with the cathode pool during normal operation of the device, a balile for restricting the cathode spot to a predetermined area of the cathode pool, an annular anode having an opening greater in extent than the active cathode area, a nest of cooling coils extending through the opening in said annular anode and directly opposed to the active cathode area, and a shield substantially enclosing the nest of cooling coils except that portion opposed to the active cathode area.

6. A vapor electric device comprising a metallic container, a pool of cathode material covering at least a portion of the bottom of the container, an electrode of resistance material in contact with the cathode pool during normal operation of the device, a baille for restricting the cathode spot to a predetermined area of the cathode pool, an annular anode having an opening greater in extent than the active cathode area, a nest of cooling coils extending through the opening in said annular anode and directly opposed to the active cathode area, a shield substantially enclosing the nest of cooling coils except that portion opposed to the active cathode area, and means for insulating said shield from said nest of cooling coils.

'7. An electric valve comprising an evacuated container, a vaporizable cathode in said container, means for periodically initiating a cathode spot on said cathode, a baille for restricting the cathode spot to a predetermined portion of the cathode surface, a cooling element placed directly above the cathode, an annular anode surrounding the cooling element, said annular anode having a central opening larger than the active cathode area and a shield for preventing direct passage of particles from the cathode to the anode surface.

8. An electric valve comprising an evacuated container, a vaporizable cathode in said container, means for periodically initiating a cathode spot in said cathode, a baffle for restricting the cathode spot to a predetermined portion of the cathode surface, a cooling element placed directly above the cathode, an annular anode surrounding the cooling element, said annular anode having a central opening larger than the active cathode area and a shield for preventing direct passage of particles from the cathode to the anode surface, said shield being insulated from said anode and said cathode.

9. An arc-discharge device comprising a container, a vaporzable electrode in said container, a make-alive electrode in contact with said vaporzable electrode during normal operation of the device, a multi-surfaced cooling element directly exposed to said vaporizable electrode, a second electrode cooperating with said Vaporizable electrode, said second electrode being placed at one side of said vaporizable electrode and said cooling element so that the arc discharge between said electrodes ilows transversely of the vapor flow between said vaporizable electrode and said cooling element.

10. A vapor-electric device comprising a vaporizable cathode, a single anode cooperating with said vaporizab-le cathode, a make-alive electrode associated with said vaporizable cathode, a nest of multi-surfaced cooling elements positioned to receive the vapor rising from said vaporizable cathode, said cooling elements being spaced from each other so that vapor readily enters between the cooling surfaces and said coole ing surfaces being laterally oiset in staggered relation to each other so that the vapor is directed from surface to surface until condensed.

HERBERT A. ROSE.

Images