US2284710A - Vacuum plumbing - Google Patents

Description

v. K. zwoRYKlN 4E1' AL 2,284,710

June 2, 1942.

` VACUUM PLUMBING Filed Jupe 1, 1940 7. yl@ E f@ @1w T ,fg

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Gttorneg Patented June 2,1942

vUNITED STATES PATE-NT oFfFlcE John E. Ruedy, Merchantvlle,-N. J., assgnors to Radio Corporation of America, a. corporation of Delaware,

l Application .ruhe 1, 1940,1serih1N0. 338,330

(ol. 35o-49.5)

1o Claims.

This inventionrelates Ato improvements* in vacuum plumbing and has Afor itsprincipal ob- -ject to provide means for inserting anobjectinto and theinvention itsel'i'will be best understood l by reference tothe'following "specification and to the` accompanying drawing, wherein l Figure'l is an elevationaliviewpartly in section showing an electron'microscopejincluding an exhaust system therefor-j'and embodyingastopcock and other elementsof avacuum plumbing system which is designed, positioned and arranged in accordance with the principle of the invention.

Figures 2, Band 4 are sectional views taken on the similarly designed sectional lines of Fig; 1 and show, schematically, the relative arrangement of the stop cock and its flow openings in `the plumbing system.

The electron microscope I which has been se-k leotedlor purposes of illustration is a so-c'alled scanning microscope and comprises a glassor metal envelope 3 which defines a main chamber`5 containing a more or less conventional arrangement of electrodes including a source of electrons, exemplified by a thermionic cathode 1, an electron lens system comprising two or more focusing cylinders 9 and and a collector elec- Atrode |3 arranged in the order named along a lens system V9, II`.

vwell known. However, inthe interest of completeness, it may here' be said that electrons emanating from the cathode 'I are formed'into a beam of the desired sharpness by the electron- As the beam emergesfrom the last lens cylinder II it isjmoved repeatedly across the specimen 23 `and scans it under the control of the deflecting lcoils I5 and I'l. `The impact of theelectron beam Yupon the specimen releases secondary electrons therefrom. The secondary electrons are collected upon the electrode I3, and the resulting current utilized (usually after ampliiication) to control the intensity of the beam of a kinescope or other viewing device l(not shown) employing a scanning system which moves in synchronism with the beam of the microscope.

Thebase I9 upon which the envelope 3 of the microscope I is fixed is preferably of rugged construction `and has a dependent collar '25 which chamber'S ofthe microscope is evacuated.

The-stop cock 2l preferably comprises a tapered cylindrical bearing 3| in which a turning `plug or stopper 33 having ahan'dle 35 is seated.

Grease or other packing material (not shown) having alow vapor pressure may be interposed between the bearing 3| and the stopper-133 ofthe cock to ensure.v a hermetic seal between these two parts. 1

1 There is a second collarl31 on the opposite side `of theV stop cock in line wththe upper collar` 25.

The `openings in thesecollars 215 -and 2l `andthe opening 2| inthe base |19 of the microscope are coaxial *and are fadapted `to lbe connected by a straight flow opening `3|] in the cock when -'the stopper 33is turned `by means of its handle 35.

This Asecond orlower collar 3l communicates with or forms part oi on auxiliary chamber -4| central axis A-A of the chamber. A pair of defleeting coils I5 and Il surround the envelope in `the vicinity of the lens system. The otherwise open end of the envelope adjacent the collector electrode is seated upon a base I9 which is provided with an opening `2|, through which the 50 specimen 23`is to be examined is introduced into thelmain chamber 5 in a position to be scanned by the electron beam (not shown) in said chamber.

The mode Vof operatingan Aelectron scanning microscope 'of this "general construction is ynow the walls of which are deflnedby a metal'bellows `or other `flexible cylinder 43, and a housing whichhas -adependentneck portion 4l. An upwardlyextending neck` 49,1forrning a continuation of the housing 45, is encompassed; by the Vbellows 43 and terminates in a curved e`nd-5| prise a gudeffor a` rack 5l, "the driving'pin 59 of which is conveniently mounted for rotation within the housing 45. A crank comprising a flexible rod or drill shaft 6| which extends through an aperture 63 in the housing 45 comprises a convenient means for imparting a driving force to rack through the pinion 59. A narrow ilexible bellows 65 which extends around the crank 6| and is sealed to the housing 45 forms an effective air tight seal about the aperture 53.

In the drawing the rack 51 is shown in its extended position, i. e., in a position whereat itrhas When the auxiliary chamber 4| reaches atmospheric pressure it may be opened by removing a cap 91 or other closure element on the lower extremity of the dependent neck 41, and the rack removed from its housing so that the specimen 23 on its leading or inner end may be changed, if desired. When the rack 51 is returned to the auxiliary chamber 4| and the cap 91 has been resealed in place, the auxiliary chamber should preferably be at least partially evacuated before the iiow opening 39, which com- Vmunicates with the main chamber 5 and the port been raised through the ilow opening 39 i1 ,1 the turning plug 33 to present the specimen -23 to the electron beam within themainl chamber 5 of the microscope. Since'that part of the auxiliary chamber which is below or beyond the collar 31 is exibly supported by the' bellows.43 it is apparent that any transverse movement im-A surface of the housing 45, as by means of a biasing spring 1|. More than one adjusting screw 61 may be employed Where necessary or desirable.

When the specimen is correctly positioned Within the microscope the auxiliary chamber 4| communicates with the main chamber 5, hence the vacuum in both chambers can be maintained or augmented through the port 29 from which a hose 13 extends to a diffusion pump 175 and a series connected for pump 11. The path of evacuation in such case is indicated by the arrows and extends through a second iiow opening 19 in the stop cock 21.

When it isdesired to change a specimen the rack is lowered by turning the crank 6|. The

handle 35 of the st op cocklis Ythen given a quarter turnto close the passageway 39, through the stopper 33, between the main chamber Band the auxiliary chamber 4|. There is a Vent 8| in the bearing Vor cylinder 3| of the stop-'cock and a complementary iiow opening V33 in the stopperdor turningplug 33. When the vent 8| and the flow opening 83 (which in Fig. l is perpendicular to the plane of projection) are aligned, air entering the vent passes through'the said opening 83 in the turning plug to a port ,85 in the bearing 3|. This port 85 in turn is connected as by ashort hose 81 to aport 89 in the collar 31 in theA auxiliary chamber 4|; hence air may enter this chamber. Since the passageway V39 connecting the rauxiliary chamber 4| and the main chamber 5 is now closed, there can be no leakage of air therebetween. It is usually convenient, however, to keep the main chamber on the pump during the period when air is being admitted to the auxiliary chamber. During this period it is desirable to maintain the series connection13 between the fore pump 11 and the diffusion pump 15. To this end the stop cock is provided with a fourth flow opening 9| and a pair of ports 93 and 95. The iiow opening 9| extends at a right angle to (and communicates with) the flow opening 19. The ports 93 and 95 are connected by the flow opening 9| when the main and auxiliary chambers 5 and 4| are connected by the flow opening 39 through which-therack 51. extends. 'A

29 to the diffusion pump 15 is opened. Such a chamber 4| if the port 89 therein is connected to thefore pump 11.` For the purpose of establishing such a connection the turning plug 33 is provided with'a fth flow opening 99 the terminals or ends of which are arranged to register with the ports 85 and 95.

VvVarious modifications of the invention will suggestthemselves to those skilled in the art. Accordingly,it.is to be understood that the foregoing description oi a preferred embodiment and useful application of the invention is to be interpreted as illustrative and not in a limiting sense except as required bythe prior art and by the spirit of the appended claims.

What is claimed is:

1. Vacuum apparatus comprising a main chamber and an auxiliary chamber having aligned openings therein, a stop cock having a ow opening adapted to connect said chamber openings, a support for an object mounted for longitudinal and'tiltable movement in said auxiliary chamber, means for moving said support into said main chamber through said openings, said openings and said main chamber being of a diameter greater than is required to accommodate said support whereby said support may be entered intosaid main `chamber through said openings and tilted therein, and means for tilting said support within said openings and relative to said main chamber, whereby to orient said object within said chamber.

2. Vacuum apparatus comprisingA a main chamber and an auxiliary chamber, a stop cock between said chambers, a flexible mountingupon which said auxiliary chamber is supported, .said chambers having normally aligned openings and said stop cock having a flow opening adaptedto connect said chamber openings, a support for an object mounted for longitudinal and tiltable movement in said auxiliary chamber, means for moving said support into said main chamber through said openings, said openings being of a diameter greater than is required to accommodate said support whereby said support may be tilted within said openings, and means for tilting said flexibly mounted auxiliaryv chamber and hence said object support, relative toV said main chamber, whereby to orient said object within said main chamber when said object support is entered therein.

3. Vacuum apparatus comprising a main chamber and an auxiliary chamber4 having aligned` openings therein, a vacuum tight stop cock mounted between saidjchambers and comprising 'a turning plug having a ow opening adapted to connect and disconnectsaid chamber openings, .a support for 'an objectmounted for movement in said auxiliary chamber, means for moving said support into and out of said main chamber through said openings, a Yportin said auxiliary chamber, means responsive to movement of said turning plug to the disconnect position for connecting said port to said pump, and means for evacuating said auxiliary chamber when said object support is confined therein.

4. The invention as set forth in claim Sand wherein means are provided for simultaneously evacuating said main and auxiliary chambers when said support extends through said flow openinginto said main chamber.

5. Vacuum apparatus comprising an evacuated main chamber and an evacuated auxiliary chamber having aligned openings therein, a vacuum tight stop cock mounted between said chambers and having a flow opening adapted to connect said chamber openings, a support for an object mounted for movement in said auxiliary chamber, means for moving said support into said main chamber through said openings, a vent in said stop cock and a port in said auxiliary chamber, means for connecting saidnport to said vent when said flow and chamber openings are unencumbered, and a closure in said auxiliary chamber permitting access to said object support.

6. Vacuum apparatus comprising a main chamber and an auxiliary chamber having aligned openings therein, a stop cock having a now opening adapted to connect said chamber openings, a diffusion pump and a fore pump, a permanent connection between said main chamber and said diffusion pump for creating a high vacuum in said chamber, means fory connecting said vfore pump to said auxiliary chamber through said stop cock when said flow y therein, a stop cock having a ow opening adapted to connect said chamber openings, a diffusion pump and a fore pump, a permanent connection between said main chamber and said diffusion pump for creating a high vacuum in said chamber, means responsive to movement of said stop cock when said flow opening is closed for connecting said fore pump to said auxiliary chamber whereby to create a low vacuum therein, means responsive to rotation of said stop cock to a position whereat said main and auxiliary chamber openings are connectedI to said flow opening for connecting said diffusion pump to said auxiliary chamber wherebyto increase the vacuum therein to a value of the order obtaining in said main chamber, a support movably mounted in said auxiliary chamber, and means operable when said main and auxiliary chamber openings are connected by said flow opening for moving said support into said main chamber through said chamber and flow openings.

8. Vacuum apparatus comprising main and auxiliary chambers provided with an interconnecting opening, movable closure means for said opening, a support movably mounted within said auxiliary chamber, means for moving said support through said opening into said main chamber when said closure is moved to its open position, and means exterior to said chambers for orienting said support within said main chamber.

9. The invention asset forth in claim 8 and wherein said auxiliary chamber is dened at lleast in part by a bellows.

10. The invention asset forth'in claim 8 and wherein means are provided for maintaining said main chamber at a relatively high vacuum during the insertion and removal of saidsupport.

VLADIMIR, K. ZWORYKIN. JOHN E. RUEDY.

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