US2007542A - Electric discharge device - Google Patents

Description

July 9, 1935. E. LUBCKE ELECTRIC DISCHARGE DEVICE Filed Jan. 11, 1934 lNVENTOR 70.57 A Jbc/(e ATTORN Y WITNESSES Patented July 9, 1935 PATENT OFFICE 2,007,542 I Y ELECTRIC DISCHARGE DEVICE Ernst Liibcke,.Berlin-Charlottenburg, Germany,

assignor to Westinghouse Electric &-Manufacturing Company, East Pittsburgh, Pa., a cor:

poration of Pennsylvania Application January 11, 1934, Serial No. In Germany January 12, 1933 i 3 Claims.

My invention relates to an electrical discharge device and circuit therefor, and especially to a type of such device in which a discharge between two electrodes provides a source of electrons for 5 an anode.

In these types of discharge devices, the anode and grid are always connected with one of the discharge electrodes with the result that a fluctuating voltage is impressed upon the grid circuit due to the ion bombardment. This fluctuating voltage may, under certain conditions, make itself very noticeable in a disturbing manner as by the production of hum in the output circuit of broadcasting tubes.

It is an object of my invention to avoid theproduction of this variable voltage.

More especially, an object of my invention is to connect the anode and grid of the work or output circuit to an auxiliary or probing electrode instead of to either of the discharge electrodes.

Further objects of my invention will become apparent from an examination of the accompanying drawing in which,

Figure l is a diagrammatic illustration of a tube and circuit therefor embodying my invention,

Fig. 2 is a graph illustrating the values'of current produced in the anode and grid circuits, and

Fig. 3 is a modification of Fig. 1.

Figure 1 of the drawing discloses an electrical discharge device preferably in the form of a mercury vapor tube having the cathode 7c and the anode a providing a discharge path or are path therebetween. These electrodes may have any suitable shape and be of any desired material. If desired, other gases, such as the noble gases, may take the place of mercury vapor in the tube.

Adjacent to this discharge path between the cathode is and anode a are the anode v and the grid g. Electrons from the discharge stream flow through the grid g to the amplifier anode c. That part of the control space of the tube in which the amplifier anode v is located is shut off in any desired manner relative to the arc space except for the passage of electrons, in order to prevent breakdowns. If the tube is of high capacity, the anode o and grid g may be provided with cooling means such as a stream of water flowing near, on or through these electrodes.

An auxiliary electrode 3, which may be desighated as a probing electrode, is located in the discharge space between the cathode 7c and the anode a. In Fig. l probing electrode s is disclosed adjacent the'cathode. It may, however, have other positions such as the central portion of the tube or a position adjacent the anode. This probing electrode s may be of any desired shape and material and if the tube is of high capacity, this probing electrode 8 may take the form of a hollow coil with a cooling stream of water passing therethrough. The work or output circuit includes the load or which is connected to the anode and also to the probing electrode 3 and to the grid 9. This anode circuit includes means for providing a suitable working potential such as the transformer circuit 1'. A local battery I? may also be included therein.

Fig. 2 shows schematically the characteristic curves of discharge tubes embodying the invention. The anode current is designated by Iv and the grid current by Ig. As is well known, the control of the tube is efiective with negative values of the grid current Ig.

The invention makes possible the variation of the value P of the voltage at which the grid current Ig becomes positive by selecting the location of the probing electrode .5. The adaptability of 1 the tube is thereby increased and the necessary pre-energization of the grid is decreased.

In sending tubes especially, the invention has the advantage of avoiding the ion bombardment effect in tubes of the prior art. These prior art tubes had their anode and grid circuits connected directly to the cathode k with the result that the grid had applied thereto, in addition to the control voltage, a variable or fluctuating voltage caused by ion bombardment. This voltage under certain conditions produces a very noticeable burn or noise. In the invention, however,

the anode circuit and grid circuit are connected to the probing electrode and the voltage caused by the discharge and superimposed on the grid voltage is so much less as to be negligible in its efiect. Furthermore, the frequency of the two voltages is difierent which also aids in making it negligible in applicants invention.

Fig. 3 discloses a modification in which the disturbing grid voltage may be kept separate from the control grid by providing a second grid such as' the grid h. The circuit of the grid h includes the probing electrode s and the load or work circuit w and an anode v as in Fig. 1. The grid g is, however, connected with the cathode is of the auxiliary discharge in Fig. 3. The current In occurring at the grid h is an electron current while that occurring on the grid 9 is an ion current.

The use of a cooling means makes it possible to locate the electrodes of the tube, particularly the probing electrode at such points where the voltage of the discharge path shows no gradients.

Although I have described herein certain specific embodiments of my invention, other modifications will be apparent to those skilled in the art. My invention, therefore, is not to be limited, except insofar as is necessitated by the prior art and as indicated in the appended claims.

I claim as my invention:

1. An electrical discharge circuit comprising a discharge device having a pair of electrodes therein providing a discharge path therebetween, an auxiliary electrode extending across said discharge path, an anode adapted to receive electrons from said discharge path, and a work circuit, said work circuit connected to said auxiliary electrode and said anode.

2. An electrical discharge circuit comprising a discharge device having a pair of electrodes therein providing a discharge path therebetween, an

in providing a discharge path therebetween, an 10 auxiliary electrode in said discharge path, an anode adapted to receive electrons from said discharge path, two grid members adjacent said anode, one of said grid members connected to one of said discharge electrodes, and a work circuit, said work circuit connected to said auxiliary electrode, said anode and the other of said grid members.

ERNST LiiBcKE.

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