US2495618A - Electrode structure for space discharge tubes - Google Patents

Description

Jan. 24, WSU G. w. WARREN ELECTRODE STRUCTURE FOR SPACE DISCHARGE TUBES Filed May 6, 1948 .INVENTOR LIA/M WFIRRGN HUB d.

atented Jan. 24, 1950 ELECTRODE STRUCTURE FOR SPACE DISCHARGE TUBES Geoffrey William'Warren, Eastcote', Pinncr, England, assignor to Limited, London,

The M-rO' Valve Company England Application May 6, 1948, Serial N 25,330 In Great Britain May 16, 1947 9 Claims. 1 The present invention relates to the construction of electrical discharge devices of the kind having at least one cathode, one anode and one control electrode. The invention is particularly,

but not exclusively, concerned withconstruc tions which provide a high resistance input such as is required for discharge devices used in electrometers.

The object of the present invention to provide improved constructions of such valves.

According to the present invention an electric discharge device of the kind specified comprises in combination a control electrode mounted-on a first member of ceramic or refractory material, an anode mounted on a second member of similar material and a cathode supported between further members fixed to or supported by either or both of the first and second members.

One construction according to the present invention will now be described by way of example, with reference to the accompanying drawings which show a thermionic valve, and in which Figure 1 shows a plan elevation of the electrode assembly only, a screen provided around said electrode assembly being shown in section, whilst Figure 2 shows a side elevation of the electrode assembly only, without the screen,

Figure 3 shown a complete valve, with the glass envelope in section,

Figure 4 shows a section of a complete valve, the same being taken substantially along the line IVIV of Fig. 3.

The unitary electrode structure is made up on two hollow rods l and 2 of ceramic or refractory material which are spaced apart substantially parallel to one another by means of nickel bands 3 and 4 fitted at each end of the rods l and 2. A directly heated cathode 5 is fitted between tags 6 and i joined to the nickel bands 3 and 4 respectively, the cathode 5 being connected to the tag 6 by a tensioning spring 8. The cathode 5 lies between and substantially parallel to the ceramic rods i and 2, and is arranged at a suitable distance from the rod upon which the control electrode 9 is mounted. The cathode leads it and l l are connected to the nickel bands 3 and bl respectively the lead it to the band 3 passing through the inside of the ceramic rod l The control electrode 9 is in the form of a hollow nickel cylinder wrapped around the ceramic rod 2 approximately mid-way between the nickel bands 3 and 4, and the anode 52 is of similar construction and is wrapped around the ceramic rod I. Lead-in connections l3 and M are made to the control electrode 9 and the anode l2 respectively, the connection i3 being taken in the opposite direction to the cathode leads 8 and l l andthe anode lead M.

The operative portion of the electrode structure is surrounded by a nickel screen E5, which. is in the form of a sheet bent into a cylinder the ends of the sheet overlapping-but not touching each other, which forms an electrostatic screen. A metal rstrip l 6 carrying getter material is strapped between the two ends of the sheet formin the screen l5; so that the getter can be fired by including .eddycurrents in the screen.

shown in Figure 3, the electrode structure is. contained in an evacuated glass envelope H, the cathode leads l6 and H and the anode lead l4 being sealed through the pinch l3, whilst the control electrode lead I3 is sealed through the wall of the envelope IT at the opposite end to the pinch l8.

It-will be appreciated that further grid or screen "electrodes may be provided which may, for ex- .-ample,.be supported from. the ceramic rod upon whichthe anode is mounted. Moreover the control grid and anode instead of being formed from -.metal sheetmay consist of a metallic layer deposited onthe ceramic rods in any known manner. Although in the arrangement described the *members supporting the control electrode and the "anode are inthe form of hollow rods or tubes, it

is to be understood that they may take other :forms, forexample cylinders of various cross-section such as square,:rectangular, elliptical and the like.

.An electric discharge device according to the present invention is of relatively simple construction, and yet nevertheless can be made with a high resistance input of, for example, more than one million megohms and up to one thousand million megohms.

I claim:

1. An electron discharge device having a cathode, anode and a control electrode, a first elongated member of heat resisting insulating material upon which is mounted said control electrode in intimate contact with said first member, a second elongated member of heat resisting insulating material upon which is mounted said anode in intimate contact with said second member, the longitudinal axis of said second member being substantially parallel to the longitudinal axis of said first member, and two cathode supporting members secured to said first and second members.

2. An electron discharge device according to 3 claim 1, in which said first and second members are of ceramic material.

3. An electron discharge device having a cathode, anode and a control electrode, a first elongated member of heat resisting insulating material around which is wound said control electrode in the form of a metal sheet, a second elongated member of heat resisting insulating material around which is wound said anode in the form of a metal sheet, the longitudinal axis of said second member being substantially parallel to the longitudinal axis of said first member, and two spacing members, said spacing members being secured to said first and second members whereby said first and second members are maintained at a predetermined spacing, and said cathode being supported between said spacing members.

4. An electron discharge device having a cathode, anode and a control electrode, a, first elongated member of heat resisting insulating material upon which is formed said control electrode consisting of a metallic layer coated on the outer surface of said first member, a second elongated member of heat resisting insulating material upon which is formed said anode consisting of a metallic layer coated on the outer surface of said second member, the longitudinal axis of said second member being substantially parallel to the longitudinal axis of said first member, and two spacing members, said spacing members being secured to said first and second members whereby first and second members are maintained at a predetermined spacing, and said cathode being supported between said spacing members.

5. An electron discharge device having a cathode, an anode, a control electrode, a first cylindrical ceramic member around which is Wound said control electrode in the form of a metal sheet, a second cylindrical ceramic member around which is wound said anode in the form of a metal sheet, said first and second members having their longitudinal axes substantially parallel, and two cathode supporting members, each of which joins one of the pair of adjacent ends of said first member and said second member, said cathode supporting members being adapted to maintain said first member and said second member at a predetermined spacing.

6. An electric discharge device comprising an elongated member of insulating material, a second elongated member of insulating material alongside of and spaced from said first elongated member, an anode constituting a metal element encircling and supported by one of said members, a control electrode constituting a metal element encircling and supported by the other of said members, and a cathode.

'7. An electric discharge device comprising an elongated member of insulating material, a second elongated member of insulating material alongside of and spaced from said first elongated member, an anode constituting a metal element encircling and supported by one of said members, a control electrode constituting a metal element encircling and supported by the other of said members, and a cathode between said anode and control electrode.

8. An electric discharge device comprising an elongated member of insulating material, a second elongated member of insulating material alongside of and spaced from said first elongated member, an anode constituting a metal element encircling and supported by one of said members, a control electrode constituting a metal element encircling and supported by the other of said members, the longitudinal axes of said members being substantially parallel and a cathode disposed between said anode and control electrode.

9. An electric discharge device comprising an elongated member of insulating material, a second elongated member of insulating material alongside of and spaced from said first elongated member, an anode constituting a metal element encircling and supported by one of said members, a control electrode constituting a metal element encircling and supported by the other of said members, the longitudinal axes of said members being substantially parallel and an elongated cathode disposed between said anode and control electrode, the longitudinal axis of the cathode being substantiall parallel to the longitudinal axes of said members.

GEOFFREY WILLIAM WARREN.

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

UNITED STATES PATENTS Number Name Date 1,925,106 Morrison Sept. 5, 1933 2,086,595 Anderson July 13, 1937 FOREIGN PATENTS Number Country Date 273,293 Great Britain Aug. 18, 1927

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