US2528437A - Multiple anode tube and method of employing the same in testing apparatus - Google Patents

Description

OYING INVENTOR. IVAN LOJOYQ BY ATTORNEY EJF" - l. L. JOY MULTIPLE ANODE TUBE AND METHOD OF EMPL Filed Aug. 4, 1945 THE SAME IN TESTING APPARATUS Oct. 31, 1950 Patented Oct. 31, 1950 MULTIPLE ANODE TUBE AND METHOD OF EMPLOYING THE SAME IN TESTING AP- PARATUS Ivan L. Joy, Topeka, Kans.

Application August 4, 1945, Serial No. 608,950

This invention relates to electrical testing equipment of the character employed in determining the presence of flaws or faults in material capable of conducting an electrical'current 'or being magnetized.

The primary object of my invention is to provide anelectron tube having special structure and characteristics and therefore, desirable for use in treating apparatus of the character just above set forth. r

A further aim of this invention is the provision of a multiple anode tube for testing apparatus, which tube has anodes arranged in balanced positions with respect to its cathode. This tube is also provided with guide plates or other members, functioning to confine the flow of electron'to the anodes in a uniform fashion.

Further aims of this invention include the provision of an electron tube for use as a part of a system for testing material, which tube has at least two pairs of anodes, the anodes of each pair being disposed in opposed relation and with respect to a cathode. Cooperating with the anodes are guiding means to insure even flow of electrons, to the end that deflection of the electrons passing to the anodes will cause a greater reaction at the anodes. Such reaction is due to varying magnetic lines of flux and this arrangement will, therefore, render the entire tube more sensitive Still further objects of the inventionare to provide an electron tube having at least fouranodes therein; to provide such a tube with a centrally disposed cathode serving all of the anodes, which anodes are of identical size and 2 Claims. (01. 250-27.5)

angularity with respect to the cathode; to provide a tube having anodes that cooperate with non-energized guide means forelectrons to concentrate the latter, and therefore, render the action of the tube more responsive to relatively slight variations in the magnetic lines of force. It'is through the medium of such variations that the character of the material being tested is determined.

Other objects of the invention will appeardur- Fig. 3 is a view similar to Fig. 2, but with guide plates in the envelope of the tube for guiding the flow of electrons from the cathode to the anodes.

Fig. 4 is a view similar to Fig. 3, but illustrating the presence of magnetic lines of force thatdefleet the electron flow. i

Fig. 5 is a similar view showing how the magnetic lines of force from the material being tested, have no effect upon the electron fiow if no defect or fault is present.

Fig. 6 is a view similar to Fig. 5, but indicating the manner in which a flaw will effect the how of electrons to at least one of the anodes.

Fig. 7 illustrates the manner in which the tube made in accordance with this invention, may be passed through a magnetic field in certain positions with respect thereto without changing the electron flow.

Fig. 8 illustrates the four-anode-tube in a cir' cuit capable of operating the tube in apparatus where testing for faults is the prime objective;

and

Fig. 9 is a vertical cross sectional view of-the multiple anode tube taken on line IXIX of Fig. 7.

Testing apparatus with which the tube made as illustrated is particularly useful, is that for determining flaws in rails. Obviously, the tube is usable where it is desirable to determine the presence of faults in any magnetizable substance; but for purpose of clarification, reference will hereinafterbe made to the multiple anode tube as being a part of testing equipment in the nature ofthat illustrated in U. S. Letters Patent No. 2,030,101, dated February 11,1936. This example is set down merely to reveal to one skilled in the art, the type of equipment wherein the multiple anode tube made pursuant to thisinvention, may be included. In that said patent, the housing 2| could carry three or four tubes of the character illustrated in Fig. 8 of the accompanying drawing. If such a tube is used in the testing apparatus, its variable sensitivity will suit any field strength and its self-balancing characteristics renders it unnecessary to usephasing amplific'a tion. The material being tested can be analyzed to a point very near its ends and the relatively small size of the tubes makes it practical to arrange them to pick up or be affected by lines of force moving in all directions. Thus, all types of defects may be detected.

Cathode ray tubes cannot be made small enough to be practical in the interception of magnetic fields'being tested. When such tubes are used, it is necessary to employ at least six to locate all types of defects. Even if itwere pos sible to dispose cathode ray tubes in the proper manner for efficient testing as contemplated by this invention, and as is possible through the use of my multiple anode tube, it would be necessary to use phasing amplification to balance out the current intensity variations, and this would be impractical as the amplifiers would have to be perfectly linear.

The answer to the problem is the small, fouranode balanced tube of the character diagrammatically shown in the drawing, wherein the numeral IEI designates an envelope, substantially cylindrical in form and mounted upon a base of well-known type for inclusion in a circuit.

The envelope has an electron emitting cathode l2 and a grid M at substantially the axis of its enclosed space, and the anodes l6, I8, 2% and 22 are positioned as shown inall of the views. These anodes are concentric with cathode l2 and are balanced with respect to their position to insure a bi-lateral sensitivity pattern which is the prime asset of the tube.

Guide plates 24 and 25 disposed in spaced apart relation and to each side of cathode l2, serve to guide the electron flow to anodes l6, I8, 26 and 22, as illustrated in Figs. 2 to 7 inclusive. If these platesZ were not present, the electron flow would be of a pattern diagrammatically shown in Fig. 2. When most of the space within envelope [0 between the anodes filled with guide plates 24 and 26 as in Fig. 3, a concentrated uniform flow is effected by the magnetic lines of force through which the tube is passed when the testing apparatus is in use.

There is no potential applied to plates 24 and 26. The anode voltage is provided through conductors 28, 38, 32 and 34 joined to anodes l6, i8, 20 and 22 respectively. This voltage is applied to the amplifier through conductor 36, having a condenser 31 interposed therein, where meters will indicate the flow of electrons and any deflection thereof that might be caused by a deviation in the magnetic lines of force due to a fiaw or fault in the material being tested. Obviously, it is known that the tubes made as illustrated are moved through magnetic lines of flux designated by the numeral 38 in Fig. 5, where no deflection thereof is occurring. The rail 46 is, in this instance, the article being tested, and it is energized as set forth in the above identified U. S. Letters Patent, to the end that said magnetic lines of flux 38, may be created.

A flaw 42 is schematically illustrated in Fig. 6.. This flaw appears in the rail 49 and as a result thereof, the magnetic lines of fiuX 44 are deflected to effect the flow of electrons to anode 18. Current is applied to spaced apart points on rail 40, and it is between these points that a number of the tubes made as illustrated, are disposed, This electro-inductive method of testing is highly successful but is made more so by the use of the multiple anode tube, especially because when the tubes are so placed as to cause the anodes l5, I8,

"20 and 22 thereof to intersect the straight lines of flux, any deviation from the straight line is more accurately reflected and measurable.

As defect 42 progresses by the tube, the reaction will be indicated on the tape of a conventional chronograph. current induced into rail 48 will fluctuate as the lengths thereof change between the points of contact of the input current. This fluctuation is balanced out within the tube circuit shown in Fig. 8.

When the defect 42 is directly below cathode l2 It must be assumed that;

for an instant, potential at anodes IE and 20 assume normal value the same as when no defect is near. Now, when the defect 42 is causing a deflection of magnetic lines of flux nearest anode i8, as shown in Fig. 6, the electrons flow from cathode [2 to anode I8 is decreased due to the fact thatthe lines of flux change the electron flow in direct proportion to the strength of flux and potential applied to the anode l8. The electrons are moved to cause a greater flow of electrons toward anode Hi. This varied potential results in lowering the potential at anode l6 and raising the potential on anode l8thus, implying changed potential at conductors 34 and 32 respectively. This potential is higher in conductor 32 and is amplified by passing to conventional current amplifiers through conductor 36. The amplified current is used to operate the chronograph to indicate the presence of flaw 42.

The action just set forth occurs twice-once when the flaw 42 passes nearest anode l8, and once when it passes nearest anode 22.

Contrary to the potential variation as just set forth when flaw 42 is nearest anode l8, the potential when'fiaw 42 is nearest anode 22 will be lower at anode 20 and therefore, lower in conductor 32. By using proper amplifiers, it is possible to amplify potential variations in both directions to produce chronographic variations when the flaw 42 passes both anode l8 and anode 22.

Anodes l6 and 22 are connected in parallel by conductor 28 and anodes I3 and 20 are connected in parallel by conductor 30. Both conductors 3D and 32 are connected to Output 36 leading to the amplifying system.

Source of current 46 is connected to cathode l2 by conductors 48 and 58 from one pole of a battery having suitable output. The other pole of battery 46 is connected to the anodes l6, l8, 2!] and 22 through resistors 52 and 54. These resistors 52 and 54 are used to allow the potentials at the said anodes to vary in accordance with the duration of the magnetic lines of force due to presence of a flaw.

The voltage on the grid is adjusted to a point .at which the electron flow is correct to allow efiicient operation of the tube. This voltage is adjusted through employment of potentiometer 56 connected to grid 14 by wire 58.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. An electron tube comprising an envelope; an electron emanating cathode in said envelope; a plurality of anodes disposed within the envelope in a circular pattern around said cathode, whereby to present a balanced electron flow within the envelope when the cathode is disposed in a magnetic field with the current flow of the magnetic field substantially parallel to said electron flow; and uncharged plates within the envelope for guiding the electrons toward the anodes, said plates being mounted parallel to and outside the normal electron flow toward the anodes.

2. An electron tube comprising an envelope; an electron emanating cathode in said envelope; a plurality of anodes disposed within the envelope in a circular pattern around said cathode, whereby to present a balanced electron flow within the envelopewhen the cathode is disposed in a magnetic field with the current flow of the magnetic field substantially parallel to said electron flow; and uncharged plates within the envelope for developing electrons outside the normal flow thereof toward the anodes, said plates being disposed parallel to and outside said normal flow of electrons, whereby to confine the electrons to a substantially rectangular space defined by the IVAN L. JOY.

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

Number 6 UNITED STATES PATENTS Name Date Holliday Jan. 20, 1931 Thompson Mar. 29, 1932 Fritz Oct. 11, 1938 Lopp Mar. 28, 1939 Fritz May 16, 1939 Barnes et al July 4, 1939 Van Overbeek et al. July 25, 1939 Okabe Jan. 16, 1940' Skellett Oct. 15, 1940

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