US1911928A - Electric glow discharge amplifying tube - Google Patents

Description

May 30, 1933.- 3 SEIBT ET AL ELECTRIC GL( )W DISCHARGE AMPLIFYING TUBE Filed Feb. 24, 193

ma Hal/mu Ble/ INVc'iNTO 55 Patented May '30, 1933 UNITED STATES GEORG-VSEIBT' AND H'ELLMUTI-I BLEY, or 'BERLINi-SGHONEBERG, GERMANY ELECTRIC GLOW DISCHARGE .AMPLIFYING UBE Application filed February'24, 1931, Serial No. 517,958, and- Germany March 17, 1930 This invention relates to glow discharge amplifying tubes in which a discharge takes place between two electrodes in such a manner that electrons are drawn from the said 5 discharge space into a second dark amplifying space which contains, in addition to one or more grids, a second anode, a so-called amplifying anode. Applicants have previously proposed to construct the first anode, viz. 1 the discharge anode, in such a manner that it shall interrupt the straight line connections between the'cathod'e and the controlling electrode which is provided between the first-and the second anode, so that the current flowing to the second anode shall mainly proceed from the outer parts of the glow discharge lying in the proximity of the edge of the first anode. This connection is further improved by the arrangement according to the present invention.

According to a physical law an ionization by a movable electron after an impact with an atom of gas could again be efi'ected only if the electron has traversed a path which corresponds at least to the so-called free path and has thereby attained a speed of 25 volts. On the other hand, if the electron can traverse only a smaller path, no ionization takes place. In the vacuum industry, this law is utilized, for instance in connection with glow discharge rectifying tubes without a controlling electrode, by

, making the distance between the anode and cathode very small at certain points as, in that case, in spite of the small path, no transition of current can take place for the reasons which have been stated. r

In the present invention, the physical la above referredto is. utilized for better localizing the discharge between the cathode and the first anode.

It is true that in this case the decrease should not be carried out to such an extent that a glow discharge no longer can take place between these two electrodes, as in that case no source of electrons for the amplifying current would be available. However, although in view of the fact that the individual parts of the discharge anode have a larger surface than the parts of the cathode lying discharge anode.

sists of a plurality preferably four, wires,f.-.

fsystemlof electrodes and it is surrounded by behind them, only the smallest distances between the cathode and the-discharge anode come tonlie within the freepath," ityis'pos'sible to prevent adischa'rge from the cathode, which may for instance be in the form of a 5 wire, only in an approximatelyperpendicular direction with respect to the discharge anode," whilst a discharge takes place towar'ds the edges ofthe discharge anode where the distances from the cathode are greater; In. this'way the glow discharge islocalized atf the points where the 'same'is utilized for the amplification current, that is to [say towards the edges orthe points or interruption of the The accompanying drawing illustrates, in plan view, one form of construction of the glow discharge amplifyingtube according to the invention, the arrangement being shown on an enlarged scale for the sake of m cljearness. The system of electrodes consists of four concentric electrodes. The outermost electrode, viz.the cathode is, conwhich- ,are'parallel to the axis of the tube. The next inner electrode, the discharge anode a consists of thefjsame number of strips parallel to the axis of the tube which belong to a cylindrical surface and each one of which is arranged oppositethe'individual wires of thecathode in such axmannerthat they screen the said wires with'respect tothe controlling electrode 8 andthe amplifyinganode a The distances between Jr: and im madeso small that the cen-' tral parts of a which are at the smallest distances from lc,lie below the free path, ,so that the; discharge takes place towards the edges oftheindividual strips of 'w Aca cording to the gas pressure, such an effect willbe secured for distances ranging between half and one millimeter-e. The amplifying anode a passes through the centre of the a helical controlling electrode 8. The distances between a and a and betweena and p s are also smaller than the length of the free path. As previously proposed by the applicants, theelectrodes are mounted on a W ,9) cathodeso that said first anode acts as a I anode.

9 (if-"the" gas andthe distance between said 55 first anode, the gas pressure of said'tube 1,911,928 iii-Z E;

foot 7 of insulating material, which is supported on the base of the glass tube 1'.

The gas pressure in the tube can thereby be reduced from about i Innis. to about 1 mm.

5 The arrangement according to the present invention is especially suitable also for such tubes which are intended to be used in connection with resistance couplingx in such a case the use oi. a large anode our- 10 rent is not important, the gas pressure can'b'e v substantially? reduced; Zso that it is possi- J "Z i ,1 21% L: ble to increase the anode voltages and also to decrease the gridcurrent which hitherto was not .possible to be entirely avoided.

lVhatwe clainiis Agas filled glow discharge tube foramn 3 c i plifying, detecting, and generating alternating electric currents, comprising a cathode, a first ,anode, a second, anode ,mounted behind A said firs t;ano de outside the space between said-cathodeandsaid first anode, and av controlling electrode mounted between said first andi'said second anode, the area of said first anodebeing greater thanthatof said screen between said i cathode; and; said c011 trolling electrode, the minimumdistance between said, cathode andsaid first anode being; not greater than therncan: free-path of the gas and the distance between said cath'-. odeandthe edges of saidfirst anode being greater than'ithe ineaniree path of the gas, so that agglow dischargetakes place from sa'clcathode only to the edges of said first gas filled glen-"discharge tubefor amplifying, detecting and generating alteri hatingelectric currents, comprising a cath- 1 f o de,fa first anode, a second anode ,niounted behind said first. anode outside'the space be-" tween sai d cathode; and said first anode, and a] controlling'electrode mounted between saidifir st' and' said second anode, the areaof saidfirstano'de being greater than that of said cathode so that said first anode'acts as ascreen between said cathode and said controlling electrode, theminimum distance bet "en said cathodeandisaid' first anode beingnot greater than the mean free path:

c'athjode'and theedges 'of'said first anode being greater than the inean freepath (if the gas-"so that a glow discharge takes place H from said cathode onlyto the edges of 1 said 5 being aboutl millimetre. 7.

In testimony whereof we have signed our names: to*this' specification. I H 7 1 v I GEORG SEIBT.-:

HELLMU IH BLEY.-

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