US2412302A - Getter - Google Patents

Description

Dec. lo, me. l R SPENCER K www GE'TTER Filed Deo. s, 1941 Patented Dec. 10, 1946 'U N ITED STATES iig-.T EN T '0 FF ICE GETTER Application December 3, 1941, Serial No. 421,403

(Cl. Z50-2.27.5)

4 Claims.

r-I'his invention relates to a getter arrangement and method for introducing a getter, particularly in connection with that ,type of discharge tube which is made with a metal envelope.

A number of discharge tubes are made with their outer envelope rof metal through which lead-in Vconductors .are `introduced by means of insulating seals. In such tubes difficulties lhave been encountered in vaporizing Vgetter materials due to the `fact that the .metal envelope electrically shields the interior of. the tube, and thus prevents the usual .induction heating for the purposes of vaporizing the getter. Various other methods of heating the vgetter have been attempted, -but heretofore yeach such attempt has encountered serious difficulties.

An object of this invention is yto devise 'an arrangement whereby .a getter may be vaporized into a metal envelope by induction heating.

Another object is to accomplish `the foregoing without producing undesired heating of anyof the glass-to-metal'seals ofthe metal envelope.

A further object is `to accomplish the heating of the getterin a simple and effective and reliable manner.

The foregoing and other objects of this invention will be best understood from the following description of an lexempliiication thereof, reference being had to the accompanying drawing, wherein:

Fig. 1 is a side view of a metal envelope tube, such as a magnetron, incorporating certain features of my invention; and

Fig. 2 is a cross-section of the getter arm taken along line 2--2 of Fig. l, and showing the auxiliary elements which are associated therewith during vaporization of the getter.

The tube shown in Fig. 1 consists of a hollow metal envelope I which may be made of a highlyconductive material, such as copper. For example, the envelope I may be part of a magnetron. Such a magnetron is provided with a number of metallic pipes 2 and 3 hermetically sealed into the tube walls and through which lead-in conductors are introduced into the tube. For example, the pipe 2 has sealed to its outer end a glass chamber 4 through the outer end of which is sealed a leadin conductor 5 which may extend to one of the electrodes within the tube, such as the cathode.

In the same way a lead-in conductor 6 which, for example, may be the high frequency lead from the tube, is sealed through the end of the pipe 3, which may constitute a lead extending from the the envelope I, serving in this instance as the anode of the magnetron. The pipe 3 may likerent.

walls of the cup I0, and generate sufficient heatl wise carry .a conductive pipe 'I which .surrounds the conductor 6 and forms therewith a concentric high frequency line. The envelope I .may be provided with one or `more additional lpipes not shown, through which lead-in conductors sealed through a glass seal at the outer end of said lpipes extend.

In addition to the above construction,there is provided a pipe or tube 8 of conductive material, such as copper, hermetically sealed in the wall of the envelope. The pipe `8 has sealed to the outer end thereof a glass envelope 9. The interior of the envelope 9 as well as that of the pipe 8 communicate with the interior of the envelope I. Within the envelope '9 is supported a metallic cup III, at the bottom of which is contained a getter material II. This getter material `may be, for example, an easily vaporizable material, such as barium, or a reaction mixture, such as barium oxide and aluminum. "The ygetter material vII is maintained within 'the cup I0 by a perforated metallic insert I2, which may be retained in place within the cup I0 by being welded thereto. The perforations in "the insert I2 Ypermit vaporized getter 'material to escape into the envelope 9. The cup "IIJ may be Asupported fby means 0f `an `open spiral spring I3, one lend of which is lwelded 'to the Acup VIIl and vthe rother end of which is of 'sufficient diameter to firmly engage the inner walls of the envelope 9, thus retaining the cup Ill rmly in place at substantially the center of said envelope 9. It will be noted that the cup Ill has its open end facing the back of the envelope 9 so as to avoid the blowing of z particles liberated within the cup I0 into the interior of the main envelope through the pipe 8.

After the tube has been exhausted and freed of occluded gases in the usual manner, the getter material I I is liberated by surrounding the glass envelope 9 with a coil I4 which is adapted to be fed with relatively high frequency induction heating current from a pair of lead-in conductors I5. These conductors I5 are adapted to be connected to a suitable source of high frequency cur- In this way currents are induced in the to raise the material I I to vaporizing or reaction temperature at which the getter material is vaporized and deposited on the walls of the envelope 9 to accomplish the usual residual gas cleanup. Thus it will be seen that the getter material is readily vaporized by induction heating without substantial interference with such action due to the fact that the discharge device involved possesses a metallic envelope.

When the coil I 4 is placed around the cup I0, it likewise approaches thei seal I6 between the pipe 8 and the glass envelope 9 so closelyV that in absence of some protective means, heat would be generated within the walls of the pipe 8 to such an eXtent as to injure said seal. I have found that this injurious heating maybe avoided without substantial interference with the heating ofY the getter by surrounding the seal I 6 with a relatively heavy ring I'I of a highly-conductive material, such as copper. The ring I1 may be supported in proper position, for example, by a standard I8. The copper ring I1 has such a low resistance that any currents which are generated in it by means of the coil I4 do not liberate a suflicient amount of heat to substantially raise the temperature of said ring I'I. .At the same time this action effectivelyprotects and shields the seal IB against the generation 'of heat adjacent said seal. In this way I have been able to effectively vaporize theV getter material II without any danger of injuring the seal I6.

Of course it is to be understood Athat this invention is not limited to the particular details as described above as many equivalents will suggest themselves to those skilled in the art. For example, the arrangement which I have shown lends Y ductive material to prevent undesired heating ofk i Y' itself to other types of heating of getter materials Y ing with the interior of said envelope, and a va-Y porizable material contained within said space adjacent the seal between said glass and conducting envelopes, said method comprising subjecting said vaporizable material to a varying magnetic iield` to produce induction heating thereof,.and surrounding said seal with a body of a good consaid seal. Y

2. The method of introducing a vaporizable material into a discharge device comprising an envelope of a conducting material, a glass envelope sealed to said envelope projecting exteriorly of said envelope and enclosing a space communicating with the interior of said envelope, and a, vaporizable material contained within said space adjacent the seal between said glass and conducting envelopes, said method comprising sub-- jecting said vaporizable `material to a varying magnetic field to produce induction heating there-r of, and surrounding said seal with a relatively massive ring of a good conductive material to prevent undesired heating of said seal.

3. `The method of introducing a vaporizable material into a discharge device comprising an envelope of a conducting material, a hollow conducting tube communicating with the interior of said envelope and sealed -to the wall thereof,V aglass envelope sealed to the outer end of said tube and enclosing a space communicating with the interiorof said tube, and a vaporizable material contained within said space adjacent the vseal between said glassl envelope and said tube, said method comprising subjecting Vsaid vaporizable materialto a varying magnetic iield to produce induction heat`` i ing thereof, and surrounding said seal with a body of a 'good conductive material toY preventvundesired heating of said seal.' i

- 4. The method of introducing a varnorizablema#V terial into a discharge device comprising an enve' lope of a conducting material, a hollow conduct-I ingY tube communicating with thev interior "of 'said envelope and sealed to the wall thereof, a glass envelope sealed tothe outer end of said tube and enclosing a space communicating with the interior of said tube, and a vaporizable materialcontained within said space adjacent the seal between saidVv glass envelope and said tube, said method com# prising subjecting said vaporizablematerial to"a varying magnetic eld to produce induction heating thereof, and surrounding said seal lwith a relatively massive ring of a good conductive materialA to prevent undesired heating of said sealt yPERCY n SPENCER. Y'

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