US3226467A

US3226467A - Double-walled ultra-high vacuum vessel defining a work chamber

Info

Publication number: US3226467A
Application number: US141053A
Authority: US
Inventors: Kienel Gerhard; Elsasser Friedrich
Original assignee: WC Heraus GmbH and Co KG
Current assignee: WC Heraus GmbH and Co KG
Priority date: 1960-09-28
Filing date: 1961-09-27
Publication date: 1965-12-28
Anticipated expiration: 1982-12-28

Description

Dec. 28, 1965 G. KIENEL ET AL 3,226,467

DOUBLE-WALLED ULTRA-HIGH VACUUM VESSEL DEFINING A WORK CHAMBER Filed Sept. 27, 1961 2 Sheets-Sheet 1 O -/'\-M s 1 K) H l5 l6 2 f 56 4 I" 22 23 lo 25 7 9 N 26- I as x 34 f FIG. 2 32 40 5a i i FIG. 3 33 3' INVENTORS GERHARD KIENEL 2 BY FRIEDRICH ELSASSER lum PM ATTORNEYS Dec. 28, 1965 G. KIENEL ET AL 3,226,467

DOUBLE-WALLED ULTRA-HIGH VACUUM VESSEL DEFINING A WORK CHAMBER Filed Sept. 27, 1961 2 Sheets-Sheet 2 VII/53%| INVENTORS GERHARD KIENEL FRIEDRICH ELSASSER Kb/sum M ATTORNEYS United States Patent 3,226,467 DOUBLE-WALLED ULTRA-HIGH VACUUM v VESSEL DEFINING A WGRK QHAIVEER Gerhard Kienel, Hanan (Main), and Friedrich Elsasser, Langenselbold, near Hanan (Main), Germany, assignors to W. C. Heracus G.m.b.H., Hanan (Main), Germany, a firm of Germany Filed Sept. 27, 1961, Ser. No. 141,053 Claims priority, application Germany, Sept. 28, 1960, H 36,080, Patent 1,829,431, H 36,083, Patent 1,829,478; Sept. 29, 1960, H 36,084, Patent 1,829,479

11 Claims. (Cl. 174-18) The present invention relates to double-walled ultrahigh vacuum vessels and to means for operating the same.

For operations and investigations in nuclear and vacuum engineering and the like which are to be carried out under a high vacuum it is known for some time to employ an apparatus in which the actual evacuated work chamber is surrounded by a protective chamber which is likewise evacuated, but independently of the work chamber. The amount of gases which might enter the work chamber through small leakages in the walls thereof may thus be reduced so considerably that an extremely high vacuum may be attained in the work chamber with a reasonable amount of pumping energy and within a short length of time. The expression ultra-high vacuum as used herein is supposed to mean pressures as low as about 10- mm. Hg and less. The vacuum which is produced in the protective chamber is usually a high vacuum, that is, one of at least 1() mm. Hg and preferably one as low as 10- mm. Hg or less. The evacuation of the protective chamber is carried out by conventional means, for example, by a mechanical backing pump and by a diffusion pump.

A similar pump unit may also be employed for evacuating the work chamber, although it is then necessary to provide suitable means for preventing a back-diffusion of the fuel vapors of the diffusion pump. These means consist, for example, of several bafiles, the last of which is located immediately in front of the work chamber and is maintained at a very low temperature, for example, of 150 C. It is, however, also possible to employ for this purpose the conventional getter ion umps or kryo-pumps which produce an ultra-high vacuum which is free of oil vapors.

For the production and maintenance of an ultra-high vacuum it is of extreme importance to prevent as much as possible the liberation of any gases and even the smallest amounts thereof. The reason for this will be evident from the following considerations:

Under atmospheric pressure, that is, at about 760 mm. Hg, one cubic meter of air contains 1.2 kg. of gas, while at a pressure of mm. Hg it only contains 10- mg. of gas which originally, that is, under atmospheric pressure, had a volume of only mm Even such extremely small amounts of gases when liberated may therefore increase the original pressure to twice its value. Such gases may be liberated, for example, from the walls of the vacuum vessel, from the materials to be treated in this vessel, and from other sources.

In order to prevent as much as possible a subsequent liberation of gases from the walls of the work chamber it is conventional for some time to heat or bake out these walls prior to the formation of the ultra-high vacuum. Such heating is usually carried out electrically, that is, either by induction or resistance. Since these walls lie between the work chamber which is maintained under an ultra-high vacuum and the surrounding protective chamber which is likewise maintained under a high vacuum, they are subjected to hardly any stresses and may therefore be made very thin. The walls themselves may therefore be used as electric resistance elements and be heated very easily and economically.

Although the above-mentioned problems are wellknown in the art and some of them have been adequately solved for some time, there is a series of questions which have as yet not been solved satisfactorily. Ultra-high vacuum apparatus are employed primarily for carrying out physical and other investigations and processes, for example, for examining very pure, gas-free surfaces, for certain evaporation processes, for use in connection with nuclear physics apparatus, such as accelerators, etc. It is also often advisable or even necessary to observe the proceedings occurring within the vacuum apparatus, to control electrical proceedings therein, or to move certain elements within the apparatus while it is in operation. For this reason, such apparatus are usually provided with inspection windows and with electrical lead-ins and lead-ins for transmitting mechanical movements into the apparatus.

Such devices have been applied for a long time in vacuum apparatus with a single wall, that is, without an evacuated protective chamber surrounding the work chamber. The inspection windows of these conventional vacuum apparatus usually consist of glass panes which are sealed around their edges by packings of an elastic material. For lead-ins for movable mechanical elements and for electric conductors, bolted sealing means with packings of elastic materials, for example, shaft sealing rings, are mostly used. Such materials can, however, not be used for ultra-high vacuum apparatus since all of them without any exception have a vapor pressure which is considerably higher than the desired vacuum.

Tightly bolted, cemented, and other solidly mounted sealing means can also be applied in double-walled vacuum apparatus only with difficulty since they must be firmly connected to the walls into which they are inserted. They are therefore secured not only to the thicker outer wall of the protective chamber, but also to the usually thinner wall of the work chamber. This involves a series of difiiculties. First, the lead-in apertures in the two walls must be in accurate alignment with each other. Second, by tightly bolting the sealing means to the thin wall of the work chamber, the latter may easily be deformed. Furthermore, it is very difiicult to carry out the necessary assembly work between the two walls and, last but not least, any exchange of such packing means requires a very great amount of time and effort.

7 The same also applies to cementing or to metallic packings which must always be properly molded to attain a proper sealing effect.

It is an object of the present invention to over-come all of these disadvantages by the provision of very simple and effective means. The invention concerns a double-walled ultra-high vacuum vessel with an outer wall which is capable of resisting the outer atmospheric pressure and forms the outer wall of a protective chamber which may be highly evacuated, and with an inner wall which separates the protective chamber from an inner work chamber in which the desired ultra-high vacuum may be produced. The invention further concerns the provision of such a double-walled ultra-high vacuum vessel with one or more devices for transmitting mechanical movements or electric currents and potentials from the outside through both walls into the work chamber, and for permitting an inspection of the closed work chamber from the outside. In combination with such an apparatus and with such devices the invention further resides in sealing these devices in the outer wall by the employment of suitable sealing means which are conventional as such and may consist of solid or elastic sealing means, for example, elastic sealing rings, packings, 'shaft sealing rings, bellows, metallic sealing means which are bolted and thereby deformed, or the like. The invention further consists in sealing such devices in the inner wall by means of free, narrow gaps which are open at both ends and have :a length of at least 10 mm.

The objects, features, and advantages of the present invention will become more clearly apparent from the following detailed detailed description thereof which is to be read with reference to the accompanying drawings, in which:

FIGURE 1 shows a diagrammatic cross section of a double-walled vacuum apparatus according to the invention;

FIGURE 2 shows an enlarged cross section of a part of the apparatus according to FIGURE 1 with a lead-in for mechanically transmitting a rotary movement to the inside of the apparatus;

FIGURE 3 shows a view of a part of the apparatus similar to FIGURE 2 with a lead-in for mechanically transmitting a reciprocating movement to the inside of the apparatus;

FIGURE 4 shows another view similar to FIGURES 2 and 3 with a lead-in for conducting electric currents of different potentials but usually of low amperages into the apparatus;

FIGURE 5 shows a further view similar to FIG- URES 2 to 4 with a lead-in for conducting a strong electric current of a single potential into the apparatus; while FIGURE 6 shows an enlarged cross section of the inspection window of the apparatus.

In the drawings, FIGURE 1 shows a general view of the entire vacuum apparatus according to the invention, while FIGURES 2 to 6 show specific features and modifications thereof. The work chamber 1 of the vacuum apparatus which is maintained under an ultra-high vacuum is defined by a wall 2 which is usually relatively thin and is, in turn, surrounded by a protective chamber 3 which is likewise evacuated and closed toward the outer atmosphere by a thicker outer wall 4 of a sufficient mechanical resistance.

The protective chamber 3 is limited at its rear side, that is, at the right side of FIGURE 1, by an oval bottom 5 surrounded by the atmosphere 5a which is welded is to the cylindrical outer wall 4, while at the front side it is provided with a cover 6 which may be closed by a lock 7 and may be opened by pivoting about a hinge 8. A vacuum-tight closure of chamber 3 is attained, for example, by a sealing ring 9 which is inserted between the flanges on wall 4 and the cover 6. Chamber 3 may be evacuated in a conventional manner through a vacuum line 10 to a vacuum of 10- to 10* mm. Hg by means of a pump unit 11. The outer wall 4 is supported by a frame, not shown.

The relatively thin inner wall 2 between the protective chamber 3 and the work chamber 1 is likewise closed at the rear side by a bottom which is integrally secured to wall 2. At the front side, wall 2 carries a cover 16 which may be closed by a lock 17 and may be opened by pivoting about a hinge 18. Work chamber 1 is mounted in the protective chamber 3 on supports 19 which are preferably insulated relative to the outer wall 4. Near its outer ends the cylindrical part of wall 2 carries contact rings 20 to which an electric current may be supplied through the conductors 21 which pass through sealed lead-in insulators 22 to connecting terminals 23 at the outside. From a suitable source, not shown, an electric current, preferably alternating current, may be supplied to terminals 23 so as to heat the cylindrical part of wall 2 to a temperature of, for example, 450 C., whereby this wall will be freed of any adsorbed or occluded gases. A vacuum line 25 passes from work chamber 1 through the outer wall 4 to a pump unit 26 which is capable of producing the desired ultrahigh vacuum of, for example, 10- or an even higher vacuum within work chamber 1. The vacuum pump units may be of the type as mentioned in the beginning. They as well as their dimensions and operation are so conventional that they do not need to be further described here- The present invention concerns primarily the provision of suitable sealing means for the lead-ins M for transmitting mechanical movements to the inside of work chamber 1, as illustrated in detail in FIGURES 2 and 3, for electrical lead-ins E, as illustrated in FIGURES 4 and 5, and for the inspection windows W, as illustrated in FIG- URE 6. The difiiculties which are mentioned in the beginning and which are overcome by the present invention are also due to the fact that these lead-ins and windows pass through or are mounted in the walls of both vessels of the vacuum apparatus and must be designed so as not only to insure for a long time a tight and reliable sealing effect but also to permit an easy installation and repair thereof.

As illustrated in FIGURE 2, for installing the lead-in M according to FIGURE 1, the outer wall 4 is provided with a bore 30 through which a rotatable shaft 31 extends which is sealed by a sealing ring 32, the outer part 33 of which is clamped by screws 34 between a fitting 35 and wall 4, while the inner part 36 thereof which is preferably provided with a spring 37 engages with shaft 31. The inside of sealing ring 32 is evacuated through bore 30 toward theprotective chamber 3. If the rotatable shaft 31 is designed as illustrated in FIGURE 2, it may also be slidable to some extent in the longitudinal direction to transmit longitudinal movements to the inside of work chamber 1. If, however, such longitudinal movements should be prevented, shaft 31 may be provided with one or more shoulders, flanges, or the like.

As shown in FIGURE 2, the diameter of the inwardly extending part 38 of shaft 31 is preferably slightly reduced and passes through a bore 39 in the inner wall 2 and through a bushing 40 thereon into work chamber 1. The length of this bushing including the thickness of wall 2 preferably amounts to at least 10 mm. Within bore 39 and bushing 40 the shaft portion 38 is surrounded by a tube 41 which is made of a material which does not release any gases, such as glass, molten quartz, gastight ceramics, or the like. This tube 41 considerably reduces the friction on the inner lead-in which is exposed to a high vacuum. Tube 41 which is of a greaterlength than that of bushing 40 including the thickness of wall 2, and thus projects therefrom, passes freely, that is, without any deformable sealing means, through bore 39 and bushing 40 and it is separated therefrom only by narrow annular spacing or diffusion gaps of a considerable length.

The lead-in sealing arrangement according to FIGURE 3 differs from that according to FIGURE 2 only insofar as a resilient member in the form of a corrugated tube or bellows 45 and a spline 46 on shaft 31 only permit the shaft to move in the longitudinal direction. The corrugated tube 45 is soldered at one end to a collar 47 on shaft 31, while its other end is secured to a plate 48 which is clamped by screws 34 to the wall 4 between a fitting in the form of a ring 49 and an outer sealing disk 50 and an inner rubber-ring 51. The inside of the corrugated tube 45 communicates through bore 30 with the vacuum in the protective chamber 3 and it may be reinforced against pressure by the insertion of coil springs or the like.

If tube 41 is made of a suitable material, preferably of molten quartz, shaft 38 will remain movable through the lead-in according to the invention even though wall 2 of work chamber 1 is heated to higher temperature, for example, to 450 C. Naturally, the inner diameter of tube 41 must then be made of a size to allow for the thermal expansion of shaft 31. As previously mentioned, when the walls of work chamber 1 are thus heated, they will be freed of any adhering, adsorbed or occluded gases to such an extent that a very high vacuum may be produced in the work chamber within a very short time.

FIGURE 4 illustrates an electric lead-in which is very similar to the shaft lead-in according to FIGURES 2 and 3. The outer wall 4 is again provided with a bore 30 which is in axial alignment with the central bore 52 of a fitting 53 which is secured by screws 34 to wall 4 and clamps a sealing disk 50 and a rubber ring 51 similarly as in FIGURE 3 tightly against wall 4. Fitting 53 has a tubular extension 54 on the outer end of which a small terminal box 55 is mounted. The outer wall 56 of terminal box 55 is provided with bores 57 through which electric conductors 58 are passed. These conductors are insulated from wall 56 and are secured gastight thereto by glass insulators 59 which are fused to the conductors and to wall 56. Conductors 58 then pass through an insulating tube 60 of plastic, ceramics, glass, quartz, or the like which is loosely inserted into

bores

52 and 30 so that the vacuum in chamber 3 also extends into the terminal box 55.

Again similarly as in FIGURES 2 and 3, wall 2 of work chamber 1 has a bore 39 and it also carries on its inner side a bushing 40 of the same inner diameter as and coaxially with bore 39. Bore 39 and bushing 40 contain an insulating tube 61 which is made of a material which does not give off any gases such as glass, molten quartz, gastight ceramics, or the like, and which encloses the conductors 58 leading into work chamber 1. Similarly as tube 41 in FIGURES 2 and 3, insulating tube 61 passes freely, that is, without any deformable sealing means through bore 39 and bushing 40 so as only to leave nar row diffusion gaps which should be of a considerable length, that is, at least mm. The conductors 58 are also passed through insulating

tubes

60 and 61 so as to leave similar diifusion gaps therein.

The separation of insulating

tubes

60 and 61 to form two parts has the advantage that bores 30 and 34 do not have to be as accurately aligned as it is necessary for a shaft lead-in as shown in FIGURES 2 and 3. The individual parts of the lead-in may therefore be more easily assembled relative to each other.

Whereas the electric lead-in according to FIGURE 4 contains two or more conductors, for example, for conducting electric currents of several dfferent but relatively low potentials into the work chamber 1, FIGURE 5 illustrates another electric lead-in for a single conductor 62 for conducting a strong current of one potential into the work chamber 1. Since this conductor 62 has a shaftlike thickness which depends upon the strength of the current to be conducted, the lead-in is designed similar to the shaft lead-ins according to FIGURES 2 and 3, except that it is more simple since the conductor 62 does not have to be movable like the shafts 31 in FIGURES 2 and 3. Conductor 62 is therefore rigidly secured to the fitting 63 which may also serve as a connecting terminal. In this event not only the conductor 62 but the fitting 63 as well are made of a highly conductive material, such as copper or the like. The sealing disk 64 which together with a rubber ring 65 is inserted between fitting 63 and. wall 4 should in this case consist of a suitable insulating material, and screws 34 which secure fitting 63 to wall 4 and clamp the sealing disk 64 thereon are also insulated from fitting 63 by insulating bushings 66.

The other features and parts of this lead-in are similar to those as described with reference to FIGURES 2 and 3 and are therefore identified by the same numerals. Tube 41 which is preferably made of molten quartz also has the purpose of electrically insulating the conductor 62 from wall 2 of the work chamber.

FIGURE 6 illustrates the application of the inventive sealing means to the inspection windows as shown at W in FIGURE 1. A window frame with an opening 71 is inserted into an aperture in a part of the outer wall 4 of chamber 3, for example, in the cover 6 as shown in FIGURE 1. The glass or quartz pane 72 is clamped by a mounting ring 73 and by screws 74 against a sealing disk 75 and a rubber ring 76 on frame 70. The number of screws 74 to be used depends upon the size of the window. After the protective chamber 3 has been evacuated, the glass or quartz pane 72 will be pressed by the outer atmospheric pressure against the sealing disk 75 and will thus be tightly sealed relative to the inside of chamber 3.

The inner wall 2 which forms the wall of work chamber 1 also has an aperture into which another window frame 77 with an opening 78 is inserted. The window pane 79 is merely held in its proper position on window frame 77 by means of another mounting ring 80 and screws 81, and does not require any special sealing means nor to be clamped tightly between frame 77 and. ring 80. Screws 81 only need to be tightened to such an extent that the edge portion of pane 79 engages flatly against frame 77. When the protective chamber 3 and the work chamber 1 are both evacuated, the forces occurring within the two chambers will be so small that practically no mechanical stresses will act upon the window pane 79 and the pane will not be pressed against the window frame 77 with such a force that it will be endangered.

The edge portion of window pane 79 which engages with the window frame 77 has a width of approximately 10 mm. Since the surfaces of both parts are not partic ularly finished and especially their engaging surfaces are not ground in accordance with each other, there will be narrow gaps 81 between them which serve as diffusion gaps similarly to the gaps 39 as described with reference to FIGURES l to 5.

The lead-in, inspection, and sealing means according to the invention preferably have the followng dimensions:

In the mechanical lead-ins according to FIGURES 2 and 3 and also in the electric lead-ins according to FIG- URE 5, the reduced shaft or conductor portion extending through the inner wall 2 has a diameter of about 12 mm. The inner diameter of quartz tube 41 which is slipped over this portion is at least 0.05 mm. but not more than 0.2 mm. greater than the diameter of this reduced portion. The wall thickness of quartz tube 41 amounts to about 2 mm. Gap 39 also has a width of at least 0.05 mm. and not more than 0.2 mm. Therefore, the inner diameter of bushing 40 amounts to about 16 mm.

Although the lead-in through the inner wall has thus relatively large gaps which ordinarily would result in a serious leakage of pressure and would thus prevent the formation and maintenance of a very high vacuum in Work chamber 1, these gaps result in the present case in a very good sealing effect since the protective chamber 3 also contains a very high vacuum and since the free path of the molecules then amounts to at least 5 cm. at about 10 mm. Hg, but generally to considerably more, for example, to about 50 cm. at 101, mm. Hg.

Although our invention has been illustrated and described with reference to the preferred embodiments thereof, we wish to have it understood that it is in no way limited to the details of such embodiments, but is capable of numerous modifications within the scope of the appended claims.

Having thus fully disclosed our invention, what we claim is:

1. In an ultra-high vacuum vessel for reactions and the like in a gas free area having an outer wall housing adapted to resist the outer atmospheric pressure, an inner wall defining an interior work chamber and spaced from said outer wall, said outer and inner walls defining a protective chamber surrounding said work chamber, independent conduit means for separately connecting said work chamber and said protective chamber to at least one pump unit for evacuating said work chamber to an ultrahigh vacuum and said protective chamber to a high vacuum, said outer and inner walls having respective apertures substantially in alignment with each other, said apertures being of substantially the same area, means extending through at least one pair of said aligned apertures in said Walls for transmitting energy from the outside into said work chamber, and mechanical sealing means for sealing said energy transmitting means relative to said outer wall, means extending through said inner wall aperture spaced from the aperture wall and extending substantially on veach side of the inner Wall, said energy-transmitting means extending through said last named means in the aperture in said inner wall in a manner so as to leave a free narrow gap connecting said work and protective chambers, said gap having a considerable length and forming a difiusion gap for substantially sealing said work chamber relative to said protective chamber.

2. In an ultra-high vacuum vessel for reactions and the like in a gas free area having an outer wall adapted to resist the outer atmosphere pressure, an inner wall defining a work chamber and spaced from said outer wall, to form an evacuable area therebetween, said outer and inner walls defining a protective chamber surrounding said work chamber, at least one pump unit for evacuating said work chamber to a high vacuum, independent connection means for separately connecting said work chamber and said protective chamber to said respective pumps, said outer and inner walls having conforming apertures substantially in alignment with each other, interconnecting means extending through at least one pair of said aligned apertures in said walls for transmitting energy from the outside into said work chamber, aligned outer and inner inspection windows connected to the wall portions surrounding at least one other pair of said aligned apertures, and mechanical sealing means in each chamber wall for separately sealing said energy transmitting means and said outer inspection window to said outer wall, means extending through said inner wall aperture spaced from the aperture wall and extending substantially on each side of the inner wall, said energy transmitting means extending through said last named means in the aperture in said inner wall and the inner inspection window being connected to said inner wall in a manner so as to leave free narrow gaps connecting said work and protective chambers and each having a considerable length and forming a diffusion gap for substantially sealing said work chamber relative to said protective chamber.

3. In an ultra-high vacuum vessel for reactions and the like in a gas free area having an outer wall adapted to resist the outer atmospheric pressure, an inner wall defining a work chamber and spaced from said outer wall, said outer and inner walls defining a protective chamber surrounding said work chamber, means for separately connecting said work chamber and said protective chamber to at least one pump unit for evacuating said work chamber to an ultra-high vacuum and said protective chamber to a high vacuum, said outer and inner walls having apertures substantially in alignment with each other for permitting the operation of reactions in the inner chamber, means extending through at least one pair of said aligned apertures in said walls for transmitting electrical energy from the outside into said work chamber, outer and inner inspection windows secured to the wall portions surrounding at least one other pair of said aligned apertures, mechanical sealing means -for separately sealing said energy transmitting means and said outer inspection window to said outer wall, and means for connecting said inner inspection window without sealing means to said inner wall, means extending through said inner wall aperture spaced from the aperture wall and extending substantially on each side of the inner wall, said energy transmitting means extending through said last named means in the aperture in said inner Wall and said inner inspection window being connected to said inner wall in a manner so as to leave free narrow gaps connecting said work and pro tective chambers and each having a considerable length and forming a diffusion gap for substantially sealing said work chamber relative to said protective chamber.

4. In an ultra-high vacuum vessel for reactions and the like in a gas free area having an outer wall adapted to resist the outer atmospheric pressure, an inner wall defining a work chamber and spaced from said outer wall, said outer and inner walls defining a protective chamber surrounding said work chamber, means for separately connecting said work chamber and said protective chamber to at least one pump unit for evacuating said work chamber to an ultra-high vacuum and said protective chamber to a high vacuum, said outer and inner Walls having apertures substantially in alignment with each other, means extending through at least one pair of said aligned apertures in said walls for transmitting energy from the outside into said work chamber, and mechanical sealing means for sealing said energy-transmitting means relative to said outer wall, means extending through said innerwall aperture spaced from the aperture wall and extending substantially on each side of the inner wall, said energy-transmitting means extending through said last named means in the aperture in said inner Wall in a manner so as to leave a free narrow gap connecting said work and protective chambers, said gap having a considerable length and forming a dilfusion gap for substantially sealing said work chamber relative to said protective chamber.

5. In an ultra-high vacuum vessel for reactions and the like in a gas free area having an outer wall adapted to resist the outer atmospheric pressure, an inner wall defining a work chamber and spaced from said outer wall, said outer and inner walls defining a protective chamber surrounding said work chamber, means for separately connecting said work chamber and said protective chamber to at least one pump unit for evacuating said work chamber to an ultra-high vacuum and said protective chamber to a high vacuum, said outer and inner walls having apertures substantially in alignment with each other, means extending through at least one pair of said aligned apertures in said walls for transmitting energy from the outside into said work chamber and leaving a free narrow gap connecting said work and protective chambers, outer and inner inspection windows secured to the wall portions surrounding at least one other pair of said aligned apertures, mechanical sealing means for separately sealing said energy-transmitting means and said outer inspection window to said outer wall, means extending through said free narrow gap spaced from the aperture wall and extending substantially on each side of the inner wall, said energy transmitting means extending therethrough, and means for connecting said inner inspection window without sealing means to said inner wall, said gap having a considerable length and forming a diffusion gap for substantially sealing said work chamber relative to said protective chamber.

6. In an ultra-high vacuum vessel for reactions and the like in a gas free area having an outer wall adapted to resist the outer atmospheric pressure, an inner wall defining a work chamber and spaced from said outer wall, said outer and inner walls defining a protective chamber surrounding said work chamber, means for separately connecting said work chamber and said protective chamber to at least one pump unit for evacuating said work chamber to an ultra-high vacuum and said protective chamber to a high vacuum, said outer and inner Walls having apertures substantially in alignment with each other, a tubular member secured to said inner wall in alignment with said aperture therein, means extending through at least one pair of said aligned apertures in said walls and through said tubular member for transmitting energy from the outside into said work chamber, and mechanical sealing means for sealing said energy-transmitting means relative to said outer wall, said energy-transmitting means extending through said aperture in said inner wall and through said tubular member in a manner so as to leave a free narrow gap connecting said work and protective chambers, said gap having a considerable length and forming a diffusion gap for substantially sealing said work chamber relative to said protective chamber.

7. In an ultra-high vacuum vessel for reactions and the like in a gass free area having an outer Wall adapted to resist the outer atmospheric pressure, an inner wall defining a work chamber and spaced from said outer wall, said outer and inner Walls defining a protective chamber surrounding said work chamber, and having a relatively higher pressure than the inner chamber means for separately connecting said work chamber and said protective chamber to at least one pump unit for evacuating said work chamber to an ultra-high vacuum and said protective chamber to a high vacuum, said outer and inner walls having apertures substantially in alignment with each other and of substantially equal dimensions, a tubular member secured to said inner wall in alignment with said aperture therein, a quartz tube loosely extending through the bore of said tubular member, means extending through at least one pair of said aligned apertures in said walls and through said quartz tube for transmitting electrical energy from the outside into said work chamber, and mechanical sealing means for sealing said energytransmitting means relative to said outer wall, said energy-transmitting means extending through said aperture in said inner wall and said quartz tube in a manner so as to leave a free narrow gap connecting said work and protective chambers, said gap having a considerable length and forming a diffusion gap for substantially sealing said work chamber relative to said protective chamber.

8. In an ultra-high vacuum vessel for recations and the like in a gas free area having an outer wall adapted to resist the outer atmospheric pressure, an inner wall defining a work chamber and spaced from said outer wall, said outer and inner walls defining a protective chamber surrounding said work chamber, means for separately connecting said work chamber and said pro tective chamber to at least one pump unit for evacuating said work chamber to an ultra-high vacuum and said protective chamber to a high vacuum, said outer and inner walls having apertures substantially in alignment with each other, a tubular member secured to said inner wall in alignment with said aperture therein, a quartz tube loosely extending through the bore of said tubular member, a rotatable shaft extending from the outside atmosphere through one pair of said aligned apertures in said walls and through said quartz tube into said work chamber, and at least one shaft sealing ring slidably connected to said shaft and secured to said outer wall for sealing said shaft relative to said outer wall, said shaft extending through said aperature in said inner wall and said quartz tube in such a manner so as to leave a free narrow gap connecting said work and protective chambers, said gap having a relatively considerable length and forming a diffusion gap for substantially sealing said Work chamber relative to said protective chamber.

9. In an ultra-high vacuum vessel for reactions in vacuo having an outer wall adapted to resist the outer atmospheric pressure, an inner wall defining a work chamher and spaced from said outer wall, said outer and inner walls defining a protective chamber area surrounding said Work chamber, conduit means for separately connecting said work chamber and said protective chamber to at least one pump unit for evacuating said work chamber to an ultra-high vacuum and said protective chamber to a high vacuum said outer and inner walls having apertures substantially in alignment with each other, a tubular member secured to said inner wall in alignment with said aperture the-rein, a quartz tube loosely extending through the bore of said tubular member from the outer to the inner chamber, a shaft adapted to reciprocate in its longitudinal direction and extending from the outside through one pair of said aligned apertures in said walls and through said quartz tube into said work chamber, a metallic corrugated resilient seal-ing member secured at one end to said shaft, at least one elastic sealing ring interposed between the other end of said metallic sealing member and said outer wall, and means for securing said other end and said sealing ring in seal-ing engagement to said outer wall, said shaft extending through said aperture in said inner wall and said quartz tube in such a manner so as to leave a free narrow gap connecting said work and protective chambers, said gap having a relatively considerable length and forming a diffusion gap for substantially sealing said work chamber relative to said protective chamber.

10. In an ultra-high vacuum vessel for manipulating reactions therein under gas free conditions having an outer wall adapted to resist the outer atmospheric pressure, an

inner wall defining a Work chamber and spaced from said outer wall, said outer and inner walls defining a protective chamber surrounding said work chamber, conduit means for separately connecting said work chamber and said protective chamber to at least one pump unit for evacuating said work chamber to an ultra-high vacuum and said protective chamber to a high vacuum, said outer and inner walls having apertures substantially in alignment with each other, a tubular member secured to said inner wall in alignment with said aperture therein, a quartz tube loosely extending through the bore of said tubular member to said work chamber, at least one electrio conductor extending from the outside of the outer wall through one pair of said aligned apertures in said Walls but without engaging with said walls, and through said quartz tube into said work chamber, and elastic insulating sealing means connecting said conductor to said outer Wall, said conductor extending through said aperture in said inner wall and said quartz tube in a manner so as to leave a free narrow gap connecting said work and protective chambers, said gap having a relatively considerable length and forming a diffusion gap for substantially sealing said work chamber relative to said protective chamber.

11. In an ultra-high vacuum vessel used for reactions therein having an outer wall adapted to resist the outer atmospheric pressure, an inner wall defining a work chamber and spaced from said outer wall, said outer and inner walls defining a protective chamber surrounding said work chamber, conduit means for separately connecting said work chamber and said protective chamber to at least one pump unit for evacuating said work chamber to an ultrahigh vacuum and said protective chamber to a high vacuum respectively, said outer and inner walls having apertures substantially in alignment with each other, a tubular member secured to said inner wall in alignment with said aperture therein and extending into said work chamber, a quartz tube loosely extending through the bore of said tubular member and having several leadin passages therein, a lead-in container hermetically closed toward the outside, elastic sealing means interposed between said container and said outer wall, means for securing said leadin container to said outer wall so as to be sealed to said outer wall by said sealing means, at least two electric conductors extending from the outside through said lead-in container, said outer and said inner walls without engaging with said walls, and through said passages in said quartz tube into said work chamber in a manner so as to leave a free narrow gap connecting said work and protective chambers, said gap being of considerable length and forming a diffusion gap for substan- 11 12 tially sealing said work chamber relative to said protective OTHER REFERENCES chamber and insulating means for insulating said concome: A High Vacuum Seal, pubhshed 1n Review ductors from said container and sald outer Wall. Scientific Instruments, v01. 15 No. 2 February 1944,

References Cited by the Examiner 5 46 and 47 Tehed Knight: Vacuum Feed-Through Bushing, IBM Tech- UNITED STATES PATENTS nical Disclosure Bulletin, v01. 2, N0. 4, December 1959. 679,898 8/1901 Jesse 74-182 1,041,485 1 9 s r 27753 X JOHN F. BURNS, Primary Examiner, 2,144,558 1/1939 Bahls 174151 2 439 30 4/1943 Heinemam 10 JOHN P. WILDMAN, Examiner.

3,018,561 1/1962 Wells

Claims

1. IN AN ULTRA-HIGH VACUUM VESSEL FOR REACTIONS AND THE LIKE IN A GAS FREE AREA HAVING AN OUTER WALL HOUSING ADAPTED TO RESIST THE OUTER ATMOSPHERIC PRESSURE, AN INNER WALL DEFINING AN INTERIOR WORK CHAMBER AND SPACED FROM SAID OUTER WALL, SAID OUTER AND INNER WALLS DEFINING A PROTECTIVE CHAMBER SURROUNDING SAID WORK CHAMBER, INDEPENDENT CONDUIT MEANS FOR SEPARATELY CONNECTING SAID WORK CHAMBER AND SAID PROTECTIVE CHAMBER TO AT LEAST ONE PUMP UNIT FOR EVACUATING SAID WORK CHAMBER TO AN ULTRHIGH VACUUM AND SAID PROTECTIVE CHAMBER TO A HIGH VACUUM, SAID OUTER AND INNER WALL HAVING RESPECTIVE APERTURES SUBSTANTIALLY IN ALIGNMENT WITH EACH OTHER, SAID APERTURES BEING OF SUBSTANTIALLY THE SAME AREA, MEANS EXTENDING THROUGH AT LEAST ONE PAIR OF SAID ALIGNED APERTURES IN SAID WALLS FOR TRANSMITTING ENERGY FROM THE OUTSIDE INTO SAID WORK CHAMBER, AND MECHANICAL SEALING MEANS FOR SEALING SAID ENERGY TRANSMITTING MEANS RELATIVE TO SAID OUTER WALL, MEANS EXTENDING THROUGH SAID INNER WALL APERTURE SPACED FROM THEAPERTURE WALL AND EXTENDING SUBSTANTIALLY ON EACH SIDE OF THE INNER WALL, SAID ENERGY-TRANSMITTING MEANS EXTENDING THROUGH SAID LAST NAMED MEANS IN THE APERTURE IN SAID INNER WALL IN A MANNER SO AS TO LEAVE A FREE NARROW GAP CONNECTING SAID WORK AND PROTECTIVE CHAMBERS, SAID GAP HAVING A CONSIDERABLE LENGTH AND FORMING A DIFFUSION GAP FOR SUBSTANTIALLY SEALING SAID WORK CHAMBER RELATIVE TO SAID PROTECTIVE CHAMBER.