US2660687A - Mercury vapor rectifier tube employing magnetic field - Google Patents

Description

Nov 24, ln953 J, H, COLEMAN 2,660,687

MERCURY VAPOR RECTIF'IER TUBE EMPLOYING 'MAGNETIC FIELD Filed 0G17. 50, 1952 fly-1 y x x L t @i 5 ff IN/ENTOR.

Im-INH. EDLE-Mam A' ORNEY Patented Nov. 24, 1953 UNITED STAT PATENT OFFICE MERCURY VAPOR RECTIF-IER-TUBE EMPLOYIlNllGrv MAGNETIC. yFIELD John HL- Coleman,A West Palm Beach; Fla., as'- sig'nor to Radio Corporationrof America, arcor-- pnrationofcelaware Application October 30, 1952, Serial No. 317,709 6i claims.4 (o1. S13- 161)v type of discharge device thathasalow. voltageA drop on the l*forward portion of: thecycle andan extremely highA inversefvoltageto prevent arc back..

This` invention also is specifically designed'V to` eliminate the slow switchinglimitations vof mer.

cu-ry vapor type-of rectifier device: so that the device may be used at muchhigher frequencies; ItV is therefore an obj ect of? this-invention to provide a nevvy and improved `mercury vapor type of dischargey device utilizing: a magnetic field for electron trapping.

Another objectief Sthis inventionis to provide amercury vvapor rectier tuberforvhighefrequency,

high-voltage. operation thatl will. have`V a high.

inverse. voltage rating.r

Aiurther object ofthis invention isftoprovide.`

ak novel mercury. vapor rectiier tube-utilizing:I an

appledtmagnetici field and employing; electron. trappingito. aid `inthe switching ofi an arczitype;

discharge.;

A still '.furthern obj ect: ofi thisf:` invention.: is toz` provide a: new andi: novel mercuryzvapor; type:

discharges devicez that.`-` utilizes-v anarc1type1 dis.-V charge. that may'berapidly Vswitched on: and4 off x These andother objectstare`r attained nrac:

cordance 1 with theigeneral aspect` of. this inven-v tion .by 'provi-ding. 1a .mercury `Vapor discharge de.-

vice comprising:V a. pair of:.spaced; apart cathodeV plates,r one normally-being in. contact.v with a. mercuryipool, and thel other supportingranfelongated gniter rod.v Surrounding the. elongated rod is agring shaped anode.- During operation, a magnetic iield is applied'parallel'to the elongated rodvfor the purpose of trapping the elec Thev electron .trapping-f, caused by the magnetic fieldand the electrode potentials,- causes :a-large nunk trons between they rod and]F the anode.

ber of mercury vapor-positive ionsv to be; formed so that a glow discharge occursvbetween-therod and anode. which in'imediately;v is transformed Z Figure lisa cross sectional View of an Vembodiment ofthis invention utilizing. an ion accelerating. gradient that it established toward the mercury pool;

Figure-21s' a cross sectional view ofanother embodiment of .this invention.

Referring now toiFigure l, there is` shown a crcssesectional view of one embodimentcf this invention. Included' in this'view is a gastight enclosure which. utilizes; the; elements of V the' structure; as shown; toformthe gas tight eni closure; The enclosureincludesa pair'ofv sube stantially parallel spaced" apart cathode disks; I 5l and I1. Separating these' twol cathodedisks'; is aY hollowtubularinsulatingV member I4; Inside theenclosuraand normallyon cathode disk Il ConnectedY to cathodeidi'skv is a mercury pool. I t.

l5' is' an elongated/fred; origniter electrode; IB

Substantially parallel tothe' twoy cathode disks I5 and y i'I'f is f an'A annular anode I I supported-hyported inV a recessedp'ortion- I3 of the 'insulating member I las shown.

The'cathode1-dislrs i5`a-nd- I1 are sealedtothei insulatingmernber It; as fisf the recessed portion I3, to form a gas ytight seal so that mercury vapor will-not escape fromftheenclosure. The Yconductive-support rodiI2isfseailecl4 inthe same mannerv toftliereeessed" insulating memberv I3 asf shown. Anyof'tliewel-l known sea1smay=beutilizedto form `the-junctions betweenthe various members; Disks: I5f" and I1'I' arey constructed of magnetic material such as- Kovar. The l insulatingv mem- Y bers I3- andl maybe-'constructed of "glassi The elements- I I, I2.; andv`l IIl are preferably substantially non-magnetic toprevent distortion.` of a` magnetic eld'.' Adjacent the cathode disksor platesfv I5 and'l'liis a magnet I Bihaving a magnetic held* substantially: in- -the direction as is indicated by the arrow and letter H. ItV should` be understood that a circular type magnetmay also beusedhcwever;` it isrdesiredf to havethe magnetic lines offlux pass Vthrough anode I I substantially parallel te the igniter rod I6 vas is shovvnf.v

Al recess portionv I3; ininsulating member. I4, is for. thepurposepo `eliminating sputtering of the mercury onto the insulating member I4 and thus .to maintainthehigh voltage characteristics of the device. The lead-in wire, or rod, |12 lshould be rigidenoughtc support theanode. I I without permitting itto bend so as tov touch the igniter electrode It, or the mercury pool I8. It should be noted that ligniter velectrode I6 extends below the anode II. This extension should' be. far enough so that theelectric field of the gniter electrode I6 appears'to be innitelylongwhen viewed by the anode II. In order to do this the igniter electrode I6 must extend below the anode iI a distance approximately equal to the radius of the anode II.

In operation of this embodiment of my invention, a potential difference is applied between the igniter I6 and the anode II. The potential difference causes electrons to be emitted 'from igniter I6 in a direction toward anode II. Due to the magnetic field the electrons will travel in a curvilinear path and will thus produce a sufficient number of positive ions to cause a glow discharge to occur between these two electrodes. This phenomena is explained more completely in a copending application of mine Serial Number 93,324, filed May 14, 1949, now Patent Number 2,615,139. When the current through the tube from the glow discharge is of suicient value, an arc discharge forms between the mercury pool E 8 and the anode I I, resulting in a discharge that has a lov.7 arc drop and a very high current rating.

The rate at which the arc discharge occurs can be made to be consistent, as well as fast, if the part of the cathode formed by cathode disk I and igniter I3 is elevated slightly in potential above the portion of the cathode formed by cathode disk I1 and mercury pool I8. This occurs due to the deflection of a large portion of the positive ions, that are formed in the glow discharge, down to bombard the mercury pool I8. The potential adjustment between these elements is accomplished by means of a resistor 2S connected between the cathode disk I5 and cathode disk I1 as shown.

When the voltage is reversed, i. e. the inverse cycle for rectication, the arc is extinguished as electrode II is now negative with respect to the cathode disks I5 and I1, the igniter electrode I6, and the mercury pool I8. Because there is no electron trapping in the inverse portion of a cycley i. e. when anode I I and rod I2 are negative with respect to the other electrodes, no glow discharge will occur. When the anode swings positive again, on the forward portion of the cycle, electron trapping again results and the process is repeated.

Referring now to Figure 2, there is a crosssectional view of an embodiment of this invention wherein an anode 2| is a washer shaped anode extending between the hollow tubular insulating members 24 and 30. Cathode disks 25 and 21 each have shielding members 22 inside the enclosure. The shielding members 22 are cylindrical and will normally contain the mercury pool 28. The purpose of these shielding members 22 is to prevent sputtering on the insulating members 24 and 30, and also to protect the glassto-metal seals between insulating members 24 and 30 and cathode disk 21 from harmful eiects of the mercury.

Since anode 2l extends through the enclosure it is especially well adapted for cooling. This is true because the outer circumference of anode EI is exterior the enclosure and, if desired, fins or other well known cooling coniigurations may be placed on the outer circumference of the anode 2|.

The other elements of Figure 2 are similar to those shown in Figure 1, as is the operation of the device, and further explanation of these elements or of the operation is not deemed necessary.

I claim:

l. A mercury vapor discharge device, comprising a gas tight enclosure, said enclosure comprising a pair of spaced apart cathode disks and insulating means intermediate the periphery of said disks, sealing means joining the ends of said disks and said insulating means in gas tight relation, a mercury pool within said enclosure and normally in contact with one of said disks, an elongated rod connected to the other of said disks and extending toward said mercury pool, said rod and said mercury pool normally being spaced apart, a ring shaped anode within said enclosure and spaced around said rod, conductive means supporting said anode and extending through said insulating means, and magnetic means adjacent said enclosure for applying a magnetic eld parallel to said rod.

2. A mercury vapor discharge device, comprising a gas tight enclosure, said enclosure comprising a pair of spaced apart cathode disks and insulating means intermediate the periphery of said disks, sealing means joining said insulating means and said disks in gas tight relation, a mercury pool within said enclosure and normally being in contact with one of said disks, an elongated rod connected to the other of said disks and extending toward said mercury pool but normally being spaced therefrom, a ring shaped anode within said enclosure and spaced around said rod, a conductive rod connected to said anode and extending through said insulating means, and a magnet means adjacent said disks exterior said enclosure and so positioned with respect to said elements that the eld of said magnet extends through said anode substantially parallel to said rod.

3. A mercury vapor discharge device, comprising a gas tight enclosure, said enclosure comprising a pair of spaced apart cathode disks and a pair of spaced apart hollow tubular insulating members intermediate the periphery of said disks, an anode plate extending between said insulating members on all sides and having a substantially round aperture therein, sealing means joining said insulating members to the periphery of said cathode disks and to said anode plate in gas tight relation, shielding means connected to said disks and extending toward said anode but spaced therefrom, a mercury pool within said enclosure and normally in contact with one of said disks and within said shielding means, an elongated rod extending from the other of said cathode disks through said aperture toward said cathode pool, said rod normally being spaced from said anode and said mercury pool, and a magnet having one pole adjacent each of said disks exterior said enclosure and so positioned with respect to said elements that the eld of said magnet extends through said anode substantially parallel to said rod.

4. A mercury vapor discharge device, comprising a gas tight enclosure, said enclosure comprising a pair of spaced apart cathode disks and insulating means intermediate the periphery of said disks, said insulating means including a recessed portion, means joining said insulating means and said disks in gas tight relation, a mercury pool within said enclosure and normally being in contact with one of said disks, an elongated rod connected to the other of said disks and extending toward said mercury pool but spaced therefrom, a ring shaped anode within said enclosure and spaced around said rod, a conductive rod extending from said anode through said recessed portion, and a magnet having one pole adjacent each of said disks and so positioned with respect to said elements that the eld of 5 said magnet extends through said anode substantially parallel to said rod.

5. A mercury vapor discharge device, comprising a gas tight enclosure, a pair of spaced apart cathode disks each having one surface within said enclosure, means to support said disks in spaced apart relationship, a mercury pool normally being in contact with one of said disks, an annular anode supported parallel to said disks intermediate thereof, an elongated igniter rod connected to the other of said disks and extending toward said mercury pool 'but spaced therefrom and through said annular anode, and means to apply a magnetic eld to said device so that said magnetic eld passes through said anode substantially parallel to said igniter rod.

6. A mercury vapor discharge device, comprising a gas tight enclosure, said enclosure com prising ra pair of spaced apart cathode disks and insulating means intermediate the periphery of said disks, sealing means joining the ends of said disks and said insulating means in gas tight relation, a mercury pool Within said enclosure and normally in contact with one of said disks, an annular shaped anode within said enclosure intermediate said disks and substantially parallel thereto, means to support said anode extending through said insulating means and sealed thereto, an elongated rod connected to the other of said disks and extending through said anode toward said mercury pool but spaced therefrom, said rod being spaced Within said anode and extending through said anode a distance substantially equal to the radius of said anode, and means to apply a magnetic eld to said device so that said magnetic field will be substantially parallel to said elongated rod.

JOI-IN I-I. COLEMAN.

No references cited.

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