US2291864A

US2291864A - Electric discharge device

Info

Publication number: US2291864A
Application number: US400276A
Authority: US
Inventors: Willard H Bennett
Original assignee: Electronic Research Corp
Current assignee: Electronic Research Corp
Priority date: 1941-06-28
Filing date: 1941-06-28
Publication date: 1942-08-04
Anticipated expiration: 1959-08-04

Description

Aug. 4, 1942. w. H. BENNETT ,2 1 P 2 ELECTRIC DISCHARGE DEVICE Filed June 28, 1941 22 I H 29 f 0 Fls a.

' INVENTOR.

WILLARD N. BENNETT BY 94.4.; n. W

ATTORNEY Patented Aug. 4, 1942 ELECTRIC DISCHARGE nnvrcn Willard H. Bennett, Newark, Ohio, assignor to Electronic Research Corporation, New Ohio, a corporation of Ohio Application June 28, 1941, Serial No. 400,276

14 Claims. (C 250- 275) This invention relates to electric discharge devices and refers more particularly to improvements in electric discharge devices of the type wherein the electrodes are enclosed in a free electron gas or, in other words, in an atmosphere in which electron attachment to molecules does not readily occur.

When operating electric dischargedevices in air, a sluggish pulsating form of discharge is obtained which may be attributed to the attachment of electrons to oxygen molecules to form molecular ions which have a much smaller mobility than electrons and appreciablysuppress ionization in the sheath. As a result, electric discharge devices operating in an atmosphere containing oxygen supply relatively low currents for a given applied voltage and are inefficient.

Generally speaking it may be said that the operating emciency of rectifiers depends on the rapidity of movement of electrons on the forward or useful half cycle and on the degree of obstruction offered to movement of ions on the inverse half cycle.

In order to arrive at the above condition, the electric discharge was effected in an atmosphere of hydrogen which was substantially free from electron attaching impurities. The hydrogen had the effect of increasing the mobility of the electrons and, as a result, improved the operating efficiency of the electric discharge de ice to some extent. However, it was discovered that the hydrogen atmosphere offered less resistance to the movement of ions in the inverse half cycle and the correspondingly increased inverse current nullified at least some of the increased efficiency. g

With the above in view, the present invention contemplates operating the electric discharge device in a gaseous atmosphere characterized in that the inverse current is reduced to a minimum and the forward or useful current is substantially increased. In accordance with this invention, the discharge takes place in a gas mixture comprising difierent free electron gases which, when combined, provide for obtaining increased operating efficiency by insuring a high rate of electron mobility in the forward half cycle and. by appreciably obstructing the movement of the ions in the inverse half cycle.

Another objectlof thisinvention is to effect the discharge in an atmosphere containing a mixture of at least two gasesone of which has characteristics similar to hydrogen in that it requires a relatively low value of energy for excitation and, is, therefore, advantageous for the 55 has been found that. the aboverelationshipbeproduction of high mobilities for free electrons. The other gas in the mixture preferably hasa higher molecular mass and serves to dampen or obstruct the movement of ions in the inverse half cyc e.

Another object of this invention is to provide a method of conditioning the gas mixture, and this object, as well as other objects, will be made more apparent as this description proceeds, es-' pecially when considered in connection with the Figure 2 is a cross sectional view taken on the line2---2 of Figure 1; and f v Figure 3 is a diagram of a circuit embodying the device shown in Figure 1.. InFigures land 2 of the drawing, I have illustrated an electric discharge device 10 having a discharge electrode II, a collecting electrode I2 and, a control electrode l3 electrically positioned between the discharge and collecting electrodes. All of the electrodes are enclosed in an inverted cup-shaped container H which, in the present instance, is metal and forms the col-' lecting electrode l2. The lower end of the container is closed by a cap l5 of'insulating material having an annular extension I6 surrounding the sidewall of the container I4 and having ,pro- L from the rod .at vertically spaced points. The emitter points l8 are directed toward the cylindrical collecting electrode and operate to dis-,

charge electricity toward the collecting electrode.

As will be presently set forth, the electric discharge between theemitter points 18 and'the collecting electrode [2 is controlled by the con-f trolelectrode IS. The control electrode l3 com-' prises a plurality of circumferentially spaced vertical grid bars l9 having the lower ends suitably supported on the cap l5 of insulating material and having the upper ends connected together by a plate 20. The grid bars are respectively positioned between adjacent emitter points [8 in such a manner that the extremities of the points substantiallyintersect a geometric circle including the outer surfaces of the grid bars 19. It

tween the grid bars l9 and the emitting points l8 affords the control of the electric discharge required to obtain high efliciency.

The control'electrode I3 is biased with a direct current potential during the operation of the electric discharge by means of an auxiliary electric discharge device 2| having a discharge electrode in the form of a point 22 electrically connected to the grid bars l9through the medium of a plate 20 and directed toward a collecting electrode 23. The collecting electrode 23 is electrically connected to the discharge electrode ll. Both the electrodes of the auxiliary discharge device 2l are housed in the upper end of the cupshaped container and, as a result, the auxiliary discharge device forms a unit with the device Hi.

In Figure 3 of the drawing I have shown a rectifier circuit embodying an electric discharge device ill of the above type. In detail, the rectifler circuit comprises a transformer 25 having a primary coil 26 and a secondary coil 21. The primary coil. 26 is connected to a source of alternating current potential and one terminal of the secondary coil is connected to the discharge electrode II. The other terminal of the secondary coil is connected to one side of the load 28 having the other side connected to the collecting electrode [2. A suitable condenser 29 is connected across the load circuit and functions to smooth out the energy delivered to the load.

The control electrode I3 is connected to opposite ends of the secondary coil through the medium of condensers 30 and 3|. This circuit supplies an alternating potential to the control electrode and the condensers 30 and 3| operate to impress a potential on thegrids of the order and magnitude of the space charge of the control electrode. As pointed out above, a direct current bias is applied to the control electrode II by the auxiliary discharge device 2|. The application of a biasing potential on the control electrode l3 aids the discharge on the forward half cycle and repels it on the inverse half cycle. It follows, therefore, that an ionization sheath is created immediately adjacent the points I8 on the discharge electrode which expels the discharge current from the sheath to the collecting electrode I2. Also, the biasing potential on the control electrode blocks reverse current on the inverse half .cycle and thereby reduces the tendency for the device to are back to a minimum. The principal objection to electric discharge devices of the general type set forth above is their lacl-r of efficiency which results from the loss of energy in both the forward and inverse half cycles of the discharge between the electrodes. As briefly pointed out above, when the discharge between the electrodes is effected through anatmosphere containing oxygen, the electrons attach to the oxygen molecules and form ions which have a relatively small mobility aslcompared to the electrons. Accordingly, ionization in the sheath immediately adjacent the discharge points is suppressed and a loss in current results. In order to overcome this loss 'in current, it has been proposed to effect the discharge in an atmosphere comprising a free electron gas such as hydrogen, nitrogen, or helium.

Although the above procedure had the effect of increasing the efiiciency of the discharge to some extent, nevertheless, it was found that-when hydrogen alone was used, the increase in current on the forward or useful half cycle, obtained by reason of the higher mobility of electrons in hydrogen, was nullified to some extent by an increase in current in the inverse half cycle. The mobility of electrons is also increased when the discharge takes place in either nitrogen or helium. out to a lesser extent than in hydrogen. However, these gases have a greater molecular mass than hydrogen and, therefore, retard the movement of ions on the inverse half cycle to a greater extent than hydrogen. Consequently, there is less waste currenton the inverse half cycle when operating the discharge in nitrogen and helium.

Another gas that may be used instead of hydrogen is deuterium. This gas has somewhat the same properties as hydrogen insofar as its effect on the electric discharge is concerned and in some instances may be superior because it has a higher molecular mass than hydrogen. In other words, the inverse current is somewhat less in deuterium than in hydrogen but not as small as in nitrogen or helium. Therefore, in order to obtain maximum forward or useful cur-. rent with the minimum inverse current, I have combined hydrogen or deuterium with nitrogen. Apparently, the percentage of hydrogen or deuterium in the mixture is not especially critical and I have found that efllcient sustained high current operation is obtained with amixtu're containing from one per cent to sixty per cent of hydrogen or deuterium and the remainder nitrogen.

Helium has also been mentioned as capable of being mixed with hydrogen or deuterium to effect eiilcient operation of the electric discharge device. I have found that relatively lower onset or gap-drop voltages are obtained when using helium instead of nitrogen. Therefore, the mixture of helium and hydrogen or deuterium may be used where relatively low voltage operation is desired.

It was found that after the electric discharge device III was initially loaded with the desired gas mixture, very sluggish operation was obtained and only a relatively small amount of current passed through the device. was due to the fact that'the gases were not chemically pure and contained electron-attaching impurities such as oxygen and moisture. However, the efliciency of the device steadily increased as operation of the latter continued and this was due to' the fact that the discharge eliminated the electron-attaching impurities in the gas mixture. Therefore, it is desirable to condition the electric discharge device subsequent to loading the device with the desired gas mixture, and this conditioning may be accomplished by effecting a relatively low current discharge of approximately .01 milliampere per discharge point for intervals ranging from fifteen seconds to two hours, This conditioning of the device is permanent and the discharge is changed from an inhibited character to a free electron discharge. v

What I claim as my invention is:

1. An electrode discharge device comprisinga This performance I and filled with a mixture of different free electron gases.

3. An electric discharge device having electrodes cooperating with each other in response to electrical power applied thereto to effect an electric discharge from one electrode to the other, and an atmosphere surrounding the electrodes and comprising a mixture of different gases substantially free from electron attaching impurities.

4. An electric discharge device comprising a collecting electrode, a discharge electrode cooperating with the collecting electrode to effect an electric discharge between the electrodes, and an atmosphere surrounding the electrodes and including a mixture of free electron gases selected from the group consisting of hydrogen, deuterium, nitrogen and helium.

5. An electric discharge device comprising, a collecting electrode, a discharge electrode having an emitting point directed toward the collecting electrode to effect an electric discharge between the point and collecting electrode, and an atmosphere surrounding the electrodes and including a mixture of gases containing hydrogen and nitrogen.

6. An electric discharge device comprising, a collecting electrode, a discharge electrode cooperating with the collecting electrode to effect an electric discharge between the electrodes, a control electrode electrically positioned between the collecting and discharge electrodes to control the discharge, and an atmosphere substantially free from electron attaching impurities surrounding the electrodes and including a mixture of gases containing hydrogen and nitrogen.

'7.'An electric discharge device comprising, a collecting electrode, a discharge electrode having an emitting point directed toward the collecting electrode to effectan electric discharge between the point and collecting electrode, a. control electrode electrically positioned between the collecting and discharge electrodes to control the discharge, and an atmosphere substantially free from electron attaching impurities surrounding 9. An electric discharge device comprising a collecting electrode, a discharge electrode directed toward the collecting electrode for effecting an electric discharge between the electrodes, and an atmosphere surrounding the electrodes and including a free electron gas mixture including deuterium and nitrogen.

10. An electric discharge device comprising a collecting electrode, a discharge electrode cooperating with the collecting electrode to effect an electric discharge between the electrodes, a con-: trol electrode electrically disposed between the discharge electrode and collecting electrode for controlling the discharge therebetween, and an atmosphere surrounding all of the electrodes and containing a mixture of free electron gases including deuterium and nitrogen.

11. An electric discharge device comprising a collecting electrode, a discharge electrode directed toward the collecting electrode for effecting an electric discharge between the electrodes, and an atmosphere surrounding the electrodes and including a free electron gas mixture including deuterium and helium.

12. In a method of conditioning electric discharge devices having electrodes operating in an atmosphere containing a mixture of different gases, that step which consists in effecting an electric discharge in the atmosphere between the electrodes for a sufficient time interval to substantially eliminate any residual impurities pres ent in the gas mixture.

13. In a method of conditioning electric discharge devices of the type=having a discharge electrode and a collecting electrode disposed in an atmosphere of hydrogen and nitrogen, that step which consists in substantially removing any electron attaching impurities from the gas mixture by connecting a high potential between the electrodes to effect an electric discharge between the electrodes through the gaseous atmosphere.

14. In a method of conditioning electric discharge devices of the type having a discharge electrode and a collecting electrode disposed in an atmosphere of gases selected from the group consisting of hydrogen, deuterium, nitrogen and helium, that step which consists in effecting an electric discharge between the electrodes through attaching impurities from the atmosphere.

WILLARD H. BENNETT.