US2168872A - High voltage and high vacuum discharge device - Google Patents

Description

Aug. 8, 1939; s, HRSCH 2,168,872

HIGH VOLTAGE AND HIGH VACUUM DISCHARGE DEVICE Original Filed Oct. 2, '1934 uunnn Summit Hind.

INVENTOR.

I 's ATTORNEY Patented Aug. 8, 1939 UNITED STATES HIGH VOLTAGE AND HIGH VACUUM DIS- CHARGE, DEVICE Samuel Hirsch, New .York, N. Y., assignor to Arthur Mutscheller, New York, N. Y.

Application October 2,

1934, Serial No. 746,528

Renewed January 23, 1939 Claims.

I have invented new and useful improvements in high voltage and. high vacuum discharge devices, of which the following is a specification.

Stated more definitely, my invention comprises 5 a new method of insulating the electrodes of high voltage discharge devices through which it becomes possible for operation at high voltage to reduce the dimensions of the device and at the same time to avoid undue strain on the vacuum containing envelope of the discharge device. It

is the equivalent to say, that for a given physical dimension of a discharge device of my invention I am able to operate it at a very much higher voltage than is possible for any of the now known devices and without having sparking over from one electrode to the other or causing puncturing of the envelope walls whereby the device becomes inoperative. I am also able to a considerable eX- tent to decrease the creeping of discharges along the vessel walls especially when during damp weather there is moisture condensed on the outside of the vessel. I

I accomplish these results by making use. of the following principle. Theminimum length of a discharge device is, of course, the distance between the electrodes plus the space required to make a vacuum-tightconnectionor-seal-between the electrode and the glass envelope. All the additional length of thedevice is principally for the purpose of insulating the electrodes to prevent discharges between them through the air or creepage' of high voltage current along the outside of the glass wall from one of the electrodes to the other. I

In a discharge device of the priorart the dimension of the device is extended, inproportion to the voltage at which the device :is to be operated, in the direction substantially parallel to the direction of the spark-overdischarge or-the direction of the electrical field. It is the equivalent of this to say, that then the voltage blocking walls are substantially in a direction'perpendicular' to the equipotential surfaces. In a device of my invention. I extend-the dimension of the device 5 in a direction substantially at right angles to the direction of the discharge outside of the-vessel or to the direction in which creepage would preferentially take place. It is again the equivalent of this to say-that the voltageblocking walls in mydevice are substantially in adirection parallel to the equipotential surfaces. This isalsosthe subject of my co-pending applications-Serial No. 651,316 filed January 12,- 1933; and Serial No. 712,441 filed FebruaryZl, 1934. But an equivalent method of attaining the same end but with the additional advantage'of not having-to deal with some'of the glass technical difficulties cOn-- nected with the forms. of the device as'disclosed in the two prior applications,- consists inproviding discs or Plates-of insulating material which can be made apart of the discharge vessel in the sense that a discharge outside of the electron discharge chamber can not take place except around the outer brim of the discs. In this way the discharge is not straight through the air and hence the maximum voltage applicable to the device is not dependent on the linear distance between the free ends of the electrodes. But it is around the discs andthe-body of the vessel, and if the diameter of the twodiscs is either equal to or greater than the diameter ofthe discharge vessel, there is no injurious eii'ect or undue strain even if discharges around the discs do takeplace.

The advantages secured through my invention are therefore twofold; first, that a very much shorter device of my invention can be operated at much highervoltages than the longitudinal types of devices of the prior art and second, if discharges do take place outside of the device, they are not likely'to cause-any damage to the device as is liable to be the case in devices of the prior art.

Other advantages of the device herein disclosed are either those or such which are similar to those set forth in my'co-pending applications above referred to.

- The discs or plates of insulating material referred to above may be any sort of a disc or plate, either solid, multiple discs or hollow and evacuated, which is capable of withstanding the in tensity of the strain resulting from the field of the voltage applied to the ends of the two electrodes of the device; Such substances may'therefore be glass, either the same glass as that of which the discharge vessel is constructed and integral with it, or a diiTerent kind, porcelain, bakelite, mica, clay, hard wax, resins, wood or in fact "any'sort or kind of dielectric substance usable forinsula= tion-ot electrical voltages. These discs are then placed either tightly'fitting over the insulated electrode-arms or they'are placed on the metallic electrodes and are then made a part of the dischargevessel or are cemented onto its body. In all cases; a discharge fromone electrode to the other must not be-possible except overthe outside and around the brim of these discs and the body of the discharge-vesesl. The cement used for fastening-the discs on to'the body of the dis charge vessel must therefore alsobe a non-con ductor so asnotto allow any discharge of ourrent from the seal-in places of the electrodes inside orfrom between the discs and the discharge vessel butonly from the ends of the electrodes and over the outside of the -brirns of the discs. The electrodes themselves "may be either insulated out to a distance from which sparking is no longer possible, or they may end at the place Where the electrodes just pass through the discs. In this case it'may be advantageous to make the discs funnel-shapedwith the widened portions directed away from each other and thereby the voltage applicable is still further increased Without having sparking over. In all cases, it is the purpose of the insulating discs to produce voltage barriers in a direction which is at right angles or perpendicular to the direction in which the discharge through air would otherwise take place.

Figures 1 to 5 illustrate a few typical applications of the principle of my invention. In Fig. ,1, a glass vessel 1 is provided with disc-like protrusions I and 6 which are integral parts of the vessel and around which a discharge from one of the electrodes, for instance electrode 8 to electrode 3, can take place. In Fig. 2, a pair of electrodes l6 and H are sealed in the ordinary way into the vessel I0. The discs of insulating material, in this case shown as hard rubber, l I and I2 are placed upon the shortened arms of the tube which arms however serve as insulation over the electrode arms l4 and I5, and with a nonconducting cement they are cemented on to the glass arms in such a way, that a discharge from one electrode to the other is only possible over and around the two discs. While the discs are not of the same material as the vessel, they are rendered electrically integral therewith through the non-conducting seals I8 and I9. In Fig. 3, still another method is shown how the voltage barrier discs 2| and 22 can be combined with the discharge vessel 20 at the places 23 and 24 so that the electrodes 25 and 26 of the device can be energized at much higher voltage than without them.

It is not necessary that always two such discs are employed, for in many cases it may be advantageous to use only one at the terminal of one of the electrodes especially if the other electrode is to be grounded or connected with a water cooling device.

Fig. 4 illustrates how the barrier discs 32 and 33 which are cemented on to the glass vessel 30 at 34 and 35, can be utilized as supports for the discharge vessel, for instance in a metallic shell 31 which in this case consists of several layers of metal. One of these layers is lead to provide the required protection against stray rays in unwanted directions; the second layer would be of steel to provide the required rigidity for the shell. The insulated cables 38 and 39 are passed into the metal shell through bushings and if the two electrodes are short as shown, it is feasible to have the high voltage carrying parts of the electrodes 39a and 38a sumciently far away from the metal shell, that sparking over at normal operation does not take place. If however still better insulation of the electrodes is desired, then the openings in the insulating discs 32 and 33 can be made small enough that the insulated cables fit tightly into these openings. With the aid of an insulating cement the insulation of the two electrodes can be still further increased to the maximum voltage that the cables 38 and 39 will stand. The bushings through which the ca bles pass can be brought closer together, if desired, in order to be able to reduce the space occupied by them to a still lower minimum. Then, by making the cables hollow and securing 'the conductors, by means of insulating supports,

in the center of the cables, it is possible to force air through these cables and into and around the electrodes of the tube and around the tube itself for the purpose of cooling. Thus, as is shown more in detail in Fig. 6, the cold air may be forced in through the cable 38 against the anode of the discharge vessel, around the bulb of the vessel and the dielectric shields out through the cable 39. Through this arrangement therefore is secured, protection against electrical shocks, protection against stray radiation and cooling of the electrodes through the passing of any convenient cooling medium that can be passed through the cables 38 and 39.

In Fig. 5 is shown a slightly difierent form of the voltage barrier which not necessarily must be a disc or plate. Any other form, that of a cup 44 and 45, a bowl either fiat or bent over cemented on to the envelope 4!] at the places 42 and 43 may be employed so long as it provides the barrier effect for discharges grom one of the two electrodes to the other over the outside of the electron discharge chamber and ti.

While these illustrations are typical, they do not describe all possible applications. Variations from these are possible while still being within the scope of the invention which is defined in the claims.

I claim:

1. An envelope of high dielectric substance being highly evacuated and having a pair of discharge electrodes sealed therein, a pair of shields of dielectric substance dielectrically integrally in contact with and mounted on the outside of said envelope, each of said shields being concentric with one of said electrodes and concavely outwardly curved from said envelope whereby said shields constitute barriers to lines of force outside said envelope.

2. A high voltage high vacuum electron discharge device comprising a pair of electron discharging and receiving electrodes sealed in an envelope of high dielectric substance, in dielectric union therewith and concentric with each of said electrodes a voltage barrier, said barrier being of high dielectric substance mounted dielectrically integrally on the outside of said envelope, be ing dish-shaped with the open side facing away from said envelope and said electrode passing through the center thereof and said barrier coverlng the parts of said envelope immediately surrounding said electrode except those of conducting substance in contact with said electrode.

3. A highly evacuated electron discharge device having an envelope of high dielectric substance and electron transmitting electrodes to be energized with high voltage sealed therein, external terminals for said electrodes, a highly dielectric shield mounted dielectrically integrally on the outside of said envelope near the seal-in place of and concentric with each of said electrodes, said shield having portions not in contact with said envelope spreading outwardly from said envelope and in a direction substantially perpendicular to the direction of electrostatic lines of force between said terminals, thereby constituting a voltage barrier.

4. In an electron discharge device according to claim 3, a metallic housing surrounding the envelope and in contact with the dielectric shields, insulated cables extending through the housing adopted to carry the high voltage and connecting with said terminals.

5. An electron discharge device according to claim 3, a metallic housing surrounding the envelope and in contact with the dielectric shields.

insulated cables extending through the housing adopted to carry the high voltage and connecting with said terminals, said cables being hollow and opening into the interior of the housing for cir' culating a cooling medium.

SAMUELHIRSCI-ll

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