US2206008A

US2206008A - Temperature compensated controlled gaseous discharge tube

Info

Publication number: US2206008A
Application number: US193305A
Authority: US
Inventors: Percy L Spencer
Original assignee: Raytheon Manufacturing Co
Current assignee: Raytheon Co
Priority date: 1938-03-01
Filing date: 1938-03-01
Publication date: 1940-06-25
Anticipated expiration: 1957-06-25

Description

June 25, 1940. P. L. SPENCRER 2,206,008 TEMPERATURE COHPENSATED CONTROLLED GASEOUS DISCHARGE TUBE Filed March 1, 1938 fiweizzai' Part L .5 Q2062" fgww A J cury vapor, supplied from Patented June 25, 1940 pun-ED sures PATENT or e I has.

macofiran momma aasnous TUBE TEHPEBA Percy L. Spencer,

or to Company, Newton,

we conmscnaaos V at Newton. Mala,

Baythcon Manufacturing tion of Delaware Application March 1,1938, Scrlal No. 193,305

Claims.

This invention relates to a temperature-compensated controlled gaseous discharge tube.

In controlled gas-filled electrical discharge tubes in which the time of initiation of the discharge is controlled by means 01' a control element, ambient temperature variations produce pressure within the tube, and the operating characteristics is particularly pronounced in inasmuch as the vapor preswith changes in temperature.

changes in the gas as a result change of the tube. This vapor-filled tubes sure varies rapidly An object of this invention is to compensate for the variations in control characteristics, due

to changes in temperature, which are produced in such controlled Another object is to accomplish the use of a magnetic field.

A further object sults by the use 01' trostatic field.

gaseous discharge tubes.

this result by is to accomplish these rea magnetic field and an elec- The foregoing and other objects oi my invention will be. best understood from the following description of an exemplification thereof,

reference being had to the accompanying drawing, wherein the diagrammatic figure represents a cross-section of a controlled gaseous discharge tube and an associated circuit embodying one form of my invention.

In the drawing, the controlled gaseous discharge tube consists of a containing a thermionic and a control electrode sealed glass envelope l cathode 2, an anode 3, 4; The envelope i is filled with an ionizable medium,-preferably mera drop of mercury 5.

The tube is preferably operated with mercury vapor pressures between though pressures outside wise be used.

1 and 100 microns, alof this region may like- It is to be understood that the envelope I may be filled with other vapors or gases at sufiiciently high pressures so that when a discharge passes, ionization occurs and a current flows between the cathode and anode at relatively low voltage drops.

The cathode 2 may consist of a hollow metal member 6 containing a plurality of. internal radial fins I. The interiors of the member 6 and the fins l are coated with emissive material, such as, for alkalineearth oxides.

a suitable electron example, the

The coated surfaces of the cathode are raised to temperature of thermionic emission by means the upper end of which of an internal heater 8, may be welded to one or the fins I and the lowerend of which may be connected tothe heater .lead H. is supported on. a reentrant stem 9 The cathode formed in the P cs envelope I. The cathode supported on said stem 8 by means of a pair of cathode support standards lll,;one of which is sealed through the stem 9 to likewise sealed through external electrical conn The control electrode with a partition l2 h therein through which between the cathode 2 provide an external nection to the cathode.

electrical con- 5 The heater lead It is the stem 9 to provide an action.

4 is preferably provided aving a center opening the discharge may pass and the anode 3. The

control electrode 4 is also supported on the stem 9 by means or a pair of standards It, one of which is sealed through the stem 9 to provide 1 an external electrical c onnection to the control electrode. In order that the lower portion of the envelope I be kept cool so vapor may condense therein,

that the mercury a radiation shieldsupported on the standards It is interposed between the cathode 2 anode I is supported within means of an anode sta the upper end of the stem 9. The the envelope I by ndard I6 sealed through and said envelope.

In order to supply the tube with energy, a

lead l1 connects of the secondary former IS. The

the anode lead I6 to one end winding l8 oi the power transtransformer a primary 20 which may be suitable source of alternating I9 is provided with connected to some current. The other endof the secondary I8 is connected by means of a lead 2| to one The other terminal of t terminal of a load device 22. he load device 22 is connectedby means of a conductor 23 to the cathode lead-inwire 24 which the cathode standards connected to one of I ll.

The two conductors Zland ll. areconnectedto a suitable source 01' heater.,,current 25 heater 8 with current of the cathode 2 to a surfaces emit electrons which thus supplies the to raise the temperature point at which thermionically.

In order to supply the control electrode 4 with a control voltage, a lead 26 connects one of the 7 standards I3 to nor voltage 21. The

one terminal of a source of'conother terminal of said source-21 is connected by means of a conductor 28 back to the conductor 24 and thus to the cathode 2.

When the various sources of potential described,

above are energized,

comes positive with res the tube is set in operation. Under these conditions, when the anode 3 'bepect to the cathode 2. a

discharge will be initiated and current will' flow through the load 22. however, has a control negative with respect t If'the control electrode 4,

voltage which is usually 0 the cathode impressed its coated 40 upon it at the time the anode s becomes positive, the initiation or the discharge is delayed until the voltage on the control electrode l falls to a predetermined minimum value which'is less negative with respect to the cathode. Under most conditions this minimum value may be slightly negative. The grid control device 11 may be adjusted to supply various control voltages to the control electrode 4, and in this way regulate or control the value oi the current flowing through the load device 22.

when the tube is operating as described above, the mercury vapor will condense at some region within the envelope I, which in the case described above will consist of the lower region ll as indicated as a shaded region in the lower part of said envelope. The vapor pressure within the envelope i, therefore, will be determined by the temperature of the portion ll. As this temperature rises and the vapor pressure rises, it will be found that the voltage on the control electrode 4 must be made more negative in order to prevent the initiation oi the discharge at any positive value of voltage impressed uponthe anode 3. Thus changes perature of the envelope I will produce changes in the operating characteristics 0! the tube.

I have found that if a transverse. magnetic field is impressed upon the tube intermediate the cathode 2 and the anode 3 within-the control electrode 4, such a transverse magnetic neld will enable the'control electrode 4 to prevent the initiation or a discharge at any positive value oi voltage applied to the model, with a smaller negative voltage applied to said control electrode I. By impressing upon with the temperature, thevariations in the characteristic oi. the control electrode l with temperature as described above may be compensated,

and the operating characteristic of the tubemay be maintained substantially constant. In order to impress such a transverse magnetic neld upon saidcontrol electrode I. The core 2! may be energized from a suitable energizing coil ii. In order to supply the coil II with a current which varies in accordance with the temperature, a thermo-couple 32 is held adjacent the envelope i at the region II. The output of the thermocouple I2 is connected by means oi a pair of leads 33 through a switch Ila to the relay device 34. The output of the relay device 84 may be connected by means of a pair 01 conductors it to energize coil 3|. The relay device It may consist oi'a relay or amplifyl l device which will supply to the coil ii a current which varies in accordance with the value-oi the current or voltage generated by the thermo-couple 32. In actual practice the coil Il may be wound so as to produce the required value of transverse magnetic flux solely by the current generated in the thermocouple I2 itself, and thus in most instances the relay device 34 may be omitted and the output 0! the thermo-couple I! connected directly 'to the energizing coil Ii.

As the temperature of the condensing r fl n it rises, the thermo-couple I! will generate an increasing current which will therefore increase the current in the coil 3i, and likewise the transverse magnetic flux impressed upon the tube by the transverse pole pieces 3|. This increase in in the ambient temthe tube such a transverse magnetic held which varies in accordance transverse magnetic nus will compensate for the decreased ability or the control electrode 4 to hold oi! positive voltages applied to the anode I, and thus a predetermined value of voltage impressed upon the control electrode I will be suiiicient to prevent a discharge from being initiated for a predetermined value of positive voltage impressed upon the anode I, irrespective of the temperature or vapor pressure conditions within the envelope I.

Instead of the thermo-couple I! being held against the outside or the envelope I, it is possible toplace it within the envelope I so as to be directly responsive to the temperature conditions in said envelope. Likewise the'thermo-couple I! could be placed in the region surrounding the envelope I so as to be responsive to the'temperature or the air surrounding said envelope. This is particularly true in the case where the tube is placed in an enclosure wherein the vapor pressure within the envelope will vary substantially in accordance with the pressure of said surrounding air. Therefore, when I use the term "ambient temperature in the specification-and claims, I use thisterminagenericsensetocoveranyoithe foregoing temperature conditions.

As set forth in my copending application, Serial No. 612,235, filed May 19, 1932, for an improvement in Electrical gaseous discharge devices, a transverse magnetic ileld impressed upon such a tube as I have described above may also be used to control the initiation of a discharge between the cathode and the anode. Thus in the drawing, the device 84 might represent a source or.

control current impressed upon the coil II, and

the device 21 might represent a source of relatively fixed bias on the electrode I. Under these conditions, when a positive voltage is impressed upon the anode 3, a discharge will not be initiated between the cathode and the anode until the transverse magnetic flux tails to a predetermined minimum value. In this way the coil 3| would control the current flowing through the load device 12 substantially as described in connection with the control exerted by the electrode 4. However, under these conditions, likewise variations in temperature or vapor pressure within the envelope will produce variations in the control characteristics of the magnetic field. This variation likewise may be compensated for by impressing an increasingly negative voltage upon the electrode 4, For this purpose the switch "a may be used to connected the output of the thermocouple it to a pair of leads", which extend to the grid control device TI. Under these conditions the grid control device 21 would beconstructedasanampliiiersothatasthe output from the thermo-couple I! increased, the voltage uponthe dectrode I would become increasingly negative. In this way the tendency for the control eiiect of the magnetic iield to vary would be counteracted by the increasingly negative bias on the control electrode 4, and a predetermined value of magnetic fleld would be enabled to prevent a discharge under a predetermined value of positive anode voltage, irrespective of chm!! in vapor pressure or temperature 'within the envelope.

bias value of direct current to the coil 3i upon response to the electrostatic potential impressed which an alternating control current could be superimposed. As the output of the thermo-couple 32 would increase, the device 34 would be arranged so as to increase the value of the bias direct current. This increase in bias current would likewise increase the direct component of flux, and would thus compensate for the variation in the control characteristics of the magnetic field. Instead of creating a bias fiux by means of the single coil 3|, an additional coil supplied with current, either directly from the thermo-couple 32 or through an intermediate relay device, could be provided on thecore 29.

As pointed out above, a wide variety of arrangements are contemplated as being included within the scope of my invention. It will be ap-- charge between said cathode and anode in response to a controlling factor impressed .on said means, an additional control' means for controlling the initiation of a discharge between said cathodeand anode in response to the energization thereof, and means responsive to the ambient temperature of said envelope for varying the energization of said additional control means.

2. In combination, an electrical space discharge tube comprising an envelope containing a. cathode, an anode, and an ionizable medium, electrostatic means for controlling the initiation of a discharge between said cathode and anode in response to the electrostatic potential impressed on said means, means for creating a magnetic field in the discharge path between said cathode and anode and adjacent said electrostatic means, and means responsive tothe ambient temperature of said envelope for varying said magnetic field.

3. In combination, an electrical space discharge tube comprising an envelope containing a cathode, ananode, and an ionizable medium, electrostatic means for controlling the initiation .of a discharge between said cathode and anode in response to the electrostatic potential impressed on said means, meansior creating a magnetic field in the discharge path between said cathode.

and anode and adjacent said electrostatic means, and marine responsive to the temperature of said envelope for varying said magnetic field.

4. In combination. an electrical space discharge tube comprising an envelope containing a' cathode, an anode, and an ionizable medium,

electrostatic means for controlling the initiation of a discharge between-saidfcathode'and anodev in response to the electrostatic potential impressed on saidmeans, means for creating a mag netic field in the discharge path between said cathode and anode and'adjacent said electrostatic means, and means responsiveto the ambient temperature oil-said envelope for varying said magnetic field. v

' 5. In combination, an electrical space discharge tube comprising anenvelope containing a cathode, an anode, and an ionizable vapor, electrostatic. means for-controlling the initiation of a discharge between said cathode and anode in on said means, means for creating a magnetic field in the discharge path between said cathode and anode and adjacent said electrostatic means, and means varying as the pressure of the vapor within said envelope varies for varying said magnetic field.

6. In combination, an electrical space discharge tube comprising an envelope containing a cathode, an anode,.and mercury vapor, electrostatic means for controlling the initiation of a discharge between said cathode and anode in response to the electrostatic potential impressed on said means, means for creating a, magnetic field in the discharge path between said cathode and anode and adjacent said electrostatic means,

and means varying as the pressure of the vapor within said envelope varies for varying said magnetic field.

7. In combination, an electrical space discharge tube comprising an envelope containing a cathode, an anode, and an ionizable medium, electrostatic means for. controlling the initiation of a discharge between said cathode and anode in response to the electrostatic potential impressed on said means, means for creating a magneticfieldintercepting the path of said discharge between said cathode and anode and adjacent said electrostatic means, and means responsive to the ambient temperature of said envelope for vary-- ing said magnetic field.

8. In combination, an electrical space discharge tube comprising an envelope containing a cathode, an anode, and an ionizable medium, a control electrode surrounding the discharge path between said cathode and anode for controlling the initiation of a discharge between said cathode and anode, means for varying the electrostatic potential of said control electrode for controlling said discharge, means for creating a 'magnetic field intercepting the path of said discharge between said cathode and anode and adjacent said control electrode, and means responsive to the ambient temperature of said envelope for varying said magnetic field.

9. In combination, an electrical space discharge tube comprising an envelope containing a cathode, an anode, and an ionizable medium, electrostatic means for controlling the initiation of a discharge between said cathode and anode in response to the electrostatic potential impressed on said means, means for creating a magnetic field in the discharge path between said cathode and anode for controlling the initiation of a discharge between said cathode and anode in response to the energization of said means, and means responsive to the ambient tempera? ture of said envelope for varying the energization of one of said control means. i

10. In combination, an electrical space dis a biasing magnetic field upon said first-named Fancy L. SPENCER. 15