US1871344A - Electron discharge device - Google Patents

Description

Aug. 9, 1932. H. c. RENTSGHLER ELECTRON DISCHARGE DEVICE Filed Jan. 3 27 INVENTOR HA2. RENTscHLER I UNITED STATES- Patented Au 9, 1932 PATENn oFFicE- HARVEY CLAYTON nnN'rsonLnR, oFfnAs'r oRANenNnw JERSE As'sIeNoR To .wns'r- 1 INGHOUSE LAMP COMPANY, A CORPORATION or PENNSYLVANIA ELECTRON DISCHARGE DEVICE Application filed January 3, 1927. Serial No. 158,503.

This invention relates to an electric discharge device having a glow discharge in a rarefied gaseous atmosphereand morespar ticularly to the production of such a device utilizing a monatomic gas and a point-toplate discharge in which the starting voltage and the operating discharge voltage fall within relatively narrow' predetermined values and in which these voltages remain fixed within these narrow limits over a long period of time.

In my copending application Serial No.

59,986, filed October 2, 1925, entitled Elec-;

tric discharge device and assigned to the Westinghouse'Lamp Company, there 1s described and'claimed a gaseous discharge de-' vice of the point-to-plate discharge type in whichthe anode or point electrode is composed of a metal of the cerium group of rare earth metals or a mixture of such metals, such as misch metal. Such device has a low starting potential and a low operating potential and is capable of use for controlling 'or regulating the plate voltage in radio receiv-- ing circuits, particularly where, the plate current is obtained from rectified andfi-ltered alternating current through the" use of socalled B-battery eliminators. Other applications of the device are in connectionwith protective devices such as over-load circuit breakers, rectifiers, discharge lamps,etc.

lVlule the characterlstlcs of this devlce are admirable for the purpose for which it is designed, it requires a relatively long period of seasoning after manufacture to develop starting and operating characteristics. The misch metal anode has a relatively low melt-, ing point so that it is not possible to elevate thetemperature thereof sufliciently to cause the gases and impurities therein to be rapidly driven off, and consequently along period of low temperature treatment is required to effect this result.

'One of the objects of the present invention, therefore, is to produce a device having characteristics similar to :the above device and in which the time required to develop the'starting and operating characteristics is very substantially reduced.-

Another object is to produce a gaseous dislife.

after appear.

.I have found that-when. the anodeof a 'point-to-plate discharge :device utilizing an atmosphere ofa monatomic gas such as argon or;a mixture of. monatomic gasesconsists of thorium, uranium or titanium and a vaporizable clean-up agent such as misch metal, is employed for purifying the gaseous filling and lowering the voltage drop through the device that the seasoning of the discharge device carrbe accomplished very quickly and.

simplyand that both a. low starting and operating potential may be obtained. The start:

, Other objectsandadvantages W111 ash...

charge device havinga long andluniform ing'potential and operating potential, more- The'misch metal appears to serve a double 1 purpose in the device. In 'the first place, the residual impurities in the gas and those which come from theelements of the tube,

such as insufi'iciently treated electrodes, will be cleaned up by the misch metal during the seasoning process; Also, during the opera-' tion of the tube the impurities'which may bevliberated from the internal parts of the device will be cleaned up and the gas maintained in'a pure condition,-thus keeping the operating characteristics of the device sub stantially constant throughout the life -thereof. At the same time, the mischsmetal, due

to its presenceon' the cathode, enables the v device to have a lower starting potential and operating potential than would be obtained if the metal of the cathode were composed solely of one of the common metals, such as nickel, iron, molybdenum, etc.

The anode being composed of a relatively refractory metal may be substantially freed of its gas content after incorporation into the device by heatingthe electrode to a rela'a tively high temperature by forcing a heavy;

or other'suitable material sealed through the electrical discharge therethrough, thereby driving the gases and impurities from the electrode very quickly and facilitating thev development of the starting and operating characteristics. The anode material acts itself as aclean-up agent during seasoning on alternating current and where lowoperating and starting potentials are not required, the misch. metal maybe omitted from the oathode and the purification of the gas effected entirely by the anode material. However, the

use of misch metal on the cathodeis pre-- ferred since it reduces. the potential drop 7 and improves the characteristics of the dev1ce.

In order that'the invention maybe more fully understood, reference will .be had to the accompanying drawing in which the single figure illustrates a discharge device'partly in section, employing the present invention.

' The device comprises an envelope Icon-g taining an anode 2, a'cath0de 3 and aifilling of a'monatomic gas, such as argon or amixture of such gases.

The. anode 2cons1sts of a wire 4 of nickel press "5 of the deviceand has a tip 6 'con-;

sisting of thorium, uranium or, titanium,-

I secured thereon, although if desired the electrode maybe composed entirely of one of I the latter metals.

The cathode 3 consists of a cylindrical plate concentric with the anode and sup portedv from the press 5 bysupport wires Z and 8.] The cathode'may be composed either of iron or molybdenum. A quantityof misch metal 9 is securedto the cathodeB, in any 'suitablemanner shown, themisch metal may 10 struck out from theelectrode. w 7

The anode'and cathode are provided with be retained on theplate electrode by astrap" current conducting leads 11 and1 2 joined to" the wire 4: and the cathodesupport 7 respectively andto the terminals 13 and M to the base 15.

plicants aforesaid application. This increase 1n the gas pressure givesconsiderably better life and less variation of voltage, for various currents when employed as a voltage regulator. For instance, witha gas pressure of about 5 mm. the voltage across the terminals may-vary from about 8t to'92 volts with a current fluctuation of from 10 to milli-- amperes, whereas with increased pressure of about 7 mm. the voltage'variation reduced to from 86 to 90 volts.

' After filling with the gas and sealing ofi, itis necessary to subject the device to a treating's'chedule to develop the starting and opcrating characteristics thereof. Preferably,- such treatment consists in operating the device on'220-v olt alternating current with aprotective resistancejin series therewith for aperiod of about 10 to 20 minutes and then seasoning the device on 110 volts alternating current for, approximately one-half hour.

Of course, the seasoning schedule may be varied within widelimits but should be cone tinued until the-electrodes are completely degassified. and the impurities in the as cleaned up as determined by the tube showing proper operating. characteristics. I have found that a 40 or watt tungsten lamp may be employed as the protector resistance for the-device during the seasoning treatment.

The misch metal is partly vaporized from the cathode preferably. before filling with. the gas and by the presence of themisch metal; in the-cathode it has a low potential drop.

will be During seasoning, the. misch metal on the cathode serves in additionto the anode material to clean up gaseous impurities- 1 above havea starting potential of from 100 to 125 volts and a: minimum operating potential of about ito.;100 volts,;depend1n-g somewhat upon the gaseous content, its pressure, the current drawn by the device, etc.

- The misch metal serves throughout the life ofIthe device to maintain the gas in pure condition and the starting and operating charac teristics uniform. I

Dueto the particular starting and operatingcharacteristics, the device is particularly Devices produced in the manner set forth suitable for use as a voltage regulator for controlling the current supplied to a, radio receivingapparatus from rectified alternating current where it isdesired to maintain a constant voltage of around 90 volts. If it is desired to. have a. total plate voltage of 180 Y volts, two such tubes may be employed in series across the line and by means of suitable resistance, intermediate voltages of desired values may be obtained.-

Obviously, the invention is susceptible to many embodiments. and various uses and many changes and modifications may be made therein without-departing from the invention.

7 In the appended claim it is to beunderstood that wherever the term thorium is employed, the metals uranium and titanium are to be considered as equivalents. I 1

vWhat is claimed is:

' A gaseous conduction-device comprising an enclosing envelope containing therein an inert gaseous filling, a thermlonlcally mactive cathode and an anode composed substantially of thorium, said cathode having a relatively large area, as compared to the area, of said anode and said cathode being coatedat least in part With a metal of thecerium group of elements, said inert gaseous filling being at a pressure of about five to seven millimeters of mercury. n In testimony whereof, I have hereunto sub scribed my name this 80th day of December, 1926. I

HARVEY CLAYTON RENTSGHLER.

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