US2461428A - Ignition device for ionic valves - Google Patents

Description

Feb. 8, 1949. u. LAMM 2,461,428

IGNITION DEVICE FOR IONIC VALVES Filed April 10, 1947.

* 6/1f0r ....2--' A 39 I U/YO Lam/11 Wow i atented Fei. s, 194d UNITE-D ham IGNITION DEVIGE FOR IONIG'VALVES m Lemm, Llldvika, elcaess sner to manna ,gvenska Elelgt islga ter s, Sw em, a vm i ation,of,Swe'gilen .aApplication April 10,

Q get, Yas- 194igcsenallnol1740555 the current, and in inverters it may cause the failure of a commutation, which acts vas-a shortcircuit if no special protective steps ;;are taken.

For restoring the cathode spot and re-igniting the excitation anode, rapidly acting re-igniting devic h e s wh c Qn rai .,-W th u -m0 l parts .f r insta c r si tanc isnitinadev ce ,s -ea le .isn or or a c iat vel ma t ones. The present invention relates ,to .,a,d for bringing suchigniting devices into .;ac tion Vat the disappearance of the cathode spot saidda ic being v ry id and ect ve n ac 'Q 1- The invention is based on ;the following 013- en/anon. If no cathode spotis p esen iwhena main anode normally is about, to ;b e, i gnited which means either that it has just heeo ne positive .or that its potential which already is positive is admitted by the grid tothe conducting plasma in the neighbourhood of the cathodewe t filid plasma will assume a positive ,potential;;-w'thespect to the cathode, often a rather high, potential, as the anodervoltage lrisesgwitho it any ignition taking place. Between the conducting wall of the vessel and the. plasma, therezislasa rule the possibilityof a ,vivid exchangeofcharges, in the first line by ion attraction andlsecondly by glow discharge which latter eventually may lead to the formation of a cathode spot on,, the wall. The latter may therefore to ..a certain extent follow the potentialof the plasma which as aforesaid lies considerably. above that of ":the cathode. to the present invention, utilized for feedingfthe instantaneous ignition device either directly or indirectly by operating a rapLdlyacting relay, for instance an ionic tube ithyratron). The direct feeding is generally preferable ,when the-current between the plasma and the wall issufi'icient to feed the ignitingdevice, sincethe agtion will then be more rapid and safe. *In'stead'of employing the wall of the vessel, other conductors ingentact vwith the plasma. may-be ,used, as is -;Ino re fully explained below.

Three forms of the invention, all arranged for a direct feeding of the igniting device, are diagrammatically illustrated in Figs. 1-5 of the accompanying drawing.

Fig. 1 shows a single anode high tension valve This potential difference is, according 8' Claims. ((31:250- 27 .5)

hav n -.,a.-Qathp ia-jeathq e s ace-.2 wit a c nd ct is l ane lqde s a a has; -P l asula ie wa si ai ie volta ,gii t gibuting conductors 4! and ananode 5. Near the cathode, there is h the, a h d lsr ee el e h earl-netted t voltage diyerter lhior -protf: t H A insi a en e th vol ag be -W s ziht -hii 142M11 rathe hi hmnihe p easio o aidturbance.

-The-ar aaselnenfld sc ibed.'o e a esi :-th o1- when th main, anode 155 1 e arm-131,5*libfilffi lifldabllfi rennet-ign te the absen eeofializathode spot o cathode, the plasma in the cathode spaceiassumes iazghi-ghqpositive potential. xFor the reasons already statednearly the; same potentialj is .communicatedalso .to the ,wall, ,so vthat a strong current flows irom-athis -wal1- across the valve i 0 tor-the iignitor iil and' thereby produces a new cathode-lspot.

- The-valve w prevents the :ieeding device .9 ofthe ignito-r from; inihiencing;andfrom beinginfiuenced by the potentialoithe wall-=when impulses are emitted from=the--saicl---device =9. ---If the valve it -is composed of a sufiicient number of dry valve plates -for its purpose, it obtains, at the lncrmal characteristic oi the dry valves, the property that the potential difference-"between h Wall andihefiathode wh c i ve l ormal, time xdoes:m admi ;an 1 ap r bl vri t sm ,a i ethu ..-a leade 1 9 leads h i n imi thedevicafi a aini t d ndih ignitor 8 is only fed from the Wall, the alvajll, which? m h lr ga edie ielie et s en e resistance of directional character, may as shown in Fig. 4 be replaced by a voltage-dependent resistance 42 without any directional character, the ohmic value of which decreases with increasing voltage. In certain cases it may consist of an ionic valve. The igniter may also be of a capacitatively acting character.

Instead of deriving the ignition impulse from the potential difierence between the wall of the vessel and the cathode, it may also be derived from a conductor inside the vessel of the character of a probe which also may serve other purposes. Figs. 2 and 3 show example hereof.

Fig. 2 shows a single-anode valve vessel for comparatively low voltage having a cathode l6, anode ll, anode sleeve i8, excitation anode [9 with a current source 29 and an ignitor El with a feeding device 22. In this form, the ignitor 21 is connected across a valve 23 to a probe 24 mounted between the mouth 01 the anode sleeve and the cathode, said probe being especially constructed for following the potential of the plasma as closely as possible, for instance provided with points or coated with an electron emissive substance, and further it may be provided with a heating device or so placed as to be heated by the surroundings, whereby it will to a certain extent obtain the character of a hot cathode. It may at the same time serve as a screen for protecting the anode against direct radiation from the cathode.

Fig. 3 .shows a polyanodic valve vessel having anodes introduced through the bottom. The cathode is designated by 3i, the anodes by- 32 and .the anode sleeves by 331. anode with its current source is not shown. In polyanodic vessels, it may be advisable to em ploy a separate conductor or probe for each anode for rapidly absorbing the higher potential which the plasma in the neighbourhood of the anode obtains when the cathode spot is extinguished. The anode sleeve itself or a member in the immediate neighbourhood thereof may be employed. Each such member may be connected to the ignitor 35 by a separate valve 35. The figure shows the anode sleeves connected in this manner. Instead of using these sleeves as probes, an insulated screen 36 which covers the lower ends thereof and possibly the bottom of the vessel may serve the same purpose.

Fig. shows another form utilizing a thyratron 31, the grid of which is connected to the wall of the valve vessel through a voltage source 38. Between the anode of the thyratron and the cathode of the main vessel is arranged a voltage source of a type which gives only short impulses. such a source is used because, as is well known, a thyratron circuit cannot be interrupted by grid control only and with a different type of source it would be difficult to break the igniter circuit after it was once established. The preferred source is a condenser 39 charged from a Voltage source through a high ohmic resistance ll and discharged through the thyratron.

I claim as my invention:

1. In ionic valves having an arcing cathode, an

' instantaneously acting igniter permanently adjacent to said cathode, a conductor insulated from said cathode and in contact with the ionized plasma occupying a current path of said valve, means-controlled by a potential difference between said conductor and said cathode, for forcing a current through said igniter, and means preventing a flow of current from the cathode to said conductor.

2. In ionic valves having an arcing cathode,

The excitation I an instantaneously acting igniter in contact with said cathode, a conductor insulated from said cathode and in contact with the ionized plasma occupying the current path of said valve, a leading connection between said conductor and said igniter, and means preventing a flow of current from the cathode to said conductor.

3. In ionic valves having an arcing cathode, an instantaneously acting igniter in contact with said cathode, a conductor insulated from said cathode and in contact with the ionized plasma occupying the current path of said valve, and a connection including a voltage dependent resistance between said conductor and said igniter.

4. In ionic valves having an arcing cathode, an instantaneously acting igniter in contact with said cathode, a conductor insulated from said cathode and in contact with the ionized plasma occupying the current path of said valve, a device for regularly feeding said igniter, and a common connection, including a substantially unidirectionally conducting valve, leading from said conductor to said device and said igniter.

5. In ionic valves having an arcing cathode, an

instantaneously acting igniter in contact with said cathode, a conducting wall insulated from said cathode and surrounding the space adjacent to said cathode, and a leading connection between said wall and said igniter.

' 6. In ionic valves having an arcing cathode, an instantaneously acting igniter permanently adjacent to said cathode, a conductor screening diiierent internal spaces of said valve from each other, and insulated from said cathode, means controlled by a potential difference between said screening conductor and said cathode, for forcing a current through said igniter, and means preventing a flow of current from the cathode to said conductor.

7. In ionic valves having an arcing cathode, an instantaneously acting igniter permanently adjacent to said cathode, a conductor screening the space adjacent to an anode of said valve from other conducting spaces thereof, means controlled by a potential difference between said conductor and said cathode for forcing a current through said igniter, and means preventing a fiow of current from the cathode to said conducton.

8. In ionic valves having an arcing cathode, an instantaneously acting igniter permanently adjacent to said cathode, a conductor insulated from said cathode occupying a current path of said valve, means for facilitating the exchange of electrons between said conductor and the ionized plasma, means, controlled by a potential difference between said conductor and said cathode, for forcing a current through said igniter and cathode, and other means for independently forcing a current through said igniter and cathode.

UNO LAMM.

REFERENCES CITED The following references are of record in the fileof this patent:

UNITED STATES PATENTS Number Name Date 2,053,437 KnoWles Sept. 8, 1936 2,144,496 Klemperer Jan. 17, 1939

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