US2107908A - Immersion starter for pool-type discharge devices - Google Patents

Description

Feb. 8, 1938. I E upp 2,107,908 I IMMERSION STARTER FOR POOL TYPE DISCHARGE DEVICES Filed Oct. 31, 1955 Inventor: Emil Rup'p,

Patented Feb. 8,1938 I i I IMIVIERSION STARTER FOR POOL-TYPE DISCHARGE DEVICES Emil Rupp, Berlin-Frohnau, Germany, assignor to General Electric Company, acorporation of New York e Application October 31, 1935, Serial No. 47,694 g In Germany November 8, 1934 2 Claims. (01. 25027.5)

,My invention relates to an improved immerat the same time a positive voltage on the anode 2.

sion starter for pool-type discharge devices. As a material for the construction of my im- It is now known that an arc discharge between proved immersion electrode I have found that a mercury pool cathode and an anode spaced graphite rods having a graphite content not in 5 therefrom can be initiated with great facility by excess of 80 per cent and a complementary promeans of an immersion electrode of .a semi-conportion of clay have many outstanding advanducting material such as silicon or tungsten cartages. The graphite may vary from the maxibide having its tip projecting below the surface mum value stated down to aminimum of about 20 of the mercury pool. While the nature of the per cent, the composition being chosen to causestarting phenomenon is not entirely understood, the specific resistivity to fall between about 100 10 it is found to differ fundamentally both in efand about 100,000 times that of mercury. While fectiveness and in amount of required starting the electrode rod may assume various shapes, I current from that obtained by the use of a meprefer to have it pointed at the active end which tallic filament projecting into the mercury such is then immersed in the mercury to a depth of as is shown, for example, in Bodde Patent No. several millimeters. The depth of immersion may 5 832,363. 1 be adjusted by corresponding adjustment of the n r t iebelieVe-d t e ar g e quantity of mercury in the cathode pool. feet of the new immersion electrode depends in .Since an unpredictable quantity of the merpa upon t a e of th ae between, its cury will vaporize during operation of the tube S rface a e adjoining erc y a n part, and remain adhering to the envelope wall, un-

up n e Creation of a high potential gradient desirable variations in the starting current may alo g" t e electrode y- Immersion Starting, occur. In Fig. 2 I have represented a form of together with the theoretical considerations starting electrode by means f which this diff w ch govern its operation are discussed in a culty may be overcome. As illustrated, the graph- 5. article by J- slepian d Ludwlsappearmg ite rod 6 is surrounded by a tube 1 of glass, at pa'ge 693 of V0]. 52 of the Transactwns of the quartz, or a similar t withstanding 1 1 1 A.I. E. E. for June, 1933. ing material from which the rod projects very I j ItY S an O jec of the present invention to P slightly, say a few tenths of a millimeter. Above vide an immersion electrode characterized by reth mercury th electrode comprises an exposed quiring a lower starting current than those conductive portion consisting in the present in- 30 a referring to the following specification taken in 5 cury pool cathode 3 adapted to cooperate in con- 5, in the a u e of Such tubes accurate viously e p y and by E eater freedom from stance of an enlarged extension 8 of the graphite starting variations. core in combination with the clamp-like ex- An understanding of the further ob ects and tremity of the conductor The depending advant e of my invention may be obtained by tion of the electrode projects downward a sufficient distance so that the core is exposed to the 35 mercury only below the surface thereof. This arrangement, which is applicable to other semiconducting starting materials than graphite, has

, connection with the accompanying drawing in which Fig. 1 illustrates an electric discharge device suitable for use with my invention, wh le Fig. 2 is a fragmentary section of the tube of Fig. the advanta th t f t L f Start ge a e ec ive startmg can be a ggg gg i a preferred form 0 complished with different depths of immersion 40 7 Referring particularly to Fig. 1, I have shown up to at abPut 5 imeters. Forthis a three-electrode discharge device comprising an reason Varlatlons t mercury level fail to envelope I which contains an anode 2 and a merefiect the r q e lgnltlon current. n quentducting an arc-like discharge through the tub adjustment of the cathode pool is unnecessary Starting of the discharge is accomplished by passand he Irregular condensatlon of the p l n h 'ing current through the lead-in connection 4 and: e v p Wall Plays y a Subordinate part.

theimmersion electrode 5. This latter consists W e I have Shown a pa u e me t essentially of a mixture of clay and graphite and of y invention, t Will f course be understood 50 h t i k s of say, 1 to 2 in t and that I do not wish to be limited thereto since length on the order of about 2 centimeters. manymodifications in the structure may be made,

I When starting current ofpa few amperes flows and I contemplate by the appended claims to fromfthej immersion electrode into the mercury cover all such modifications as fall within the 55. pool a main discharge will take place if there is true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:-

1. In an electric discharge device, an anode, a mercury pool cathode and a starting electrode supported in cooperative relation with said cathode, said electrode comprising an exposed conductive portion above said mercury pool and a depending portion projecting below the surface of the pool during the normal operation of the device, said last-named portion consisting of an insulating sheath and a core of a semi-conducting material having a specific resistivity between about 100 and 100,000 times that of mercury, the core being substantially enclosed by the sheath and being exposed to the mercury only below the surface thereof.

2. In an electric discharge device, an anode, a mercury pool cathode and a starting electrode supported in cooperative relation with said cathode, said electrode comprising an exposed conductive portion above said mercury pool and a portion projecting below the surface of the pool during the normal operation of the device, said last-named portion comprising an insulating sheath and a core of semi-conducting material having a specific resistivity between about 100 and 100,000 times that of mercury,'the core being substantially enclosed by the sheath but having a tip projecting therethrough into contact with the mercury below the surface thereof.

EMIL RUPP.

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