US3009050A - Electron beam means for initiating chemical reactions - Google Patents

Description

MTHQ4 X 390092059 Nov. 14, 1961 K. H. STEIGERWALD 3,

ELECTRON BEAU HEANS FOR INITIATING CHDIIUAL REACTIONS Filed Feb. 18, 1957 4 Sheets-Sheet 1 if 36d v 5: 50 l 20 J6 70 IN VEN TOR. I?! //7 VZ J'IF/iflm Y MM %4 W K Arm/mew 1 1961 K. H. STEIGERWALD 3,009,050

ELECTRON saw mus FOR mmumc CHEMICAL amc'non's Filed Feb. 18, 1957 4 Sheets-Sheet 2 II/III!IIIIII/IIIIIIIII/III Nov. 14, 1961 K. H. STEIGERWALD ELECTRON BEAM MEANS FOR INITIATING CHEMICAL REACTIONS V 4 Sheets-Sheet 3 Filed Feb. 18, 1957 F I g- 3 I A94 /50 I/l g m 10 INVEN TOR.

14, 1961 K. H. STEIGERWALD 3,009,050

ELECTRON BEAM MEANS FOR INITiATING CHEMICAL REACTIONS Filed Feb. 18, 195? 4 Sheets-Sheet 4 I &4

F I g. 7

F lg. 5

.' IN VEN TOR.

4 TIP/NEW United States Patent 3,009,050 ELECTRON BEAM MEANS FOR INITIATING CHEMICAL REACTIONS Karl Heinz Steigerwald, Heidenheim, Germany, asslguor to Carl Zeiss, Wurttemberg, Germany, a corporation of Germany Filed Feb. 18, 1957, Ser. No. 640,828 15 Claims. (Cl. 219-69) This application is a continuation in part of my copending application Serial No. 258,672, filed November 28, 1951, now Patent No. 2,793,281, and relates the use of a focused beam of electrons as a heat source for causing a chemical reaction to occur between a body and a gaseous atmosphere surrounding the body.

My above noted co-pending application sets forth the novel use of a focused electron beam for drilling holes of cylindrical and conical shape in solid bodies by raising the temperature of a small, sharply defined area of the body to be drilled to such a temperature that the material within that area is vaporized and thereby produces a hole of any desired shape.

In the instant application, however, the body to be worked upon is immersed in a gaseous atmosphere which will support a chemical reaction with the body upon which the electron beam is focused.

Thus, as will be set forth hereinafter, the drilling of holes in certain materials may proceed at a substantially lower temperature than was the case of the above noted co-pending application, since at some lower temperature a chemical reaction will be started within the limited confines of the area being heated so that the desired holes are drilled in view of the chemical reaction, rather than by sheer vaporization of the material to be drilled.

In a similar manner my novel invention is useful in applications wherein the surface of the body is to be chemically coated, or where only discreet portions of the surface are to be chemically coated. In these applications, the focal point of the electron beam and the material to be worked are moved relative to one another so that the local heat source raises the temperature of the surface to initiate a chemical reaction between those portions of the surface which are impinged upon by the electron beam and the gaseous atmosphere in which it is immersed.

Clearly, this novel system could be extended to applications other than coating a material for protective purposes, or other similar purposes, and could be directed to the production of chemical compounds which are produced by the chemical reaction between the surface of the material and the gaseous atmosphere. Thus, my novel invention is adaptable to the production of chemical compounds which, with the use of other types of heat sources, would be extremely diflicult, since in the use of other types of heat sources it is extremely difiicult to raise a very small portion of a surface to an extremely high temperature in a very short time and still keep a low average temperature of the body being heated.

Accordingly, the primary object of my invention is to cause a chemical reaction between the surface of a material and a gaseous atmosphere by means of a heat source constituted of a focused beam of charged particles.

Another object of my invention is to treat a material with a focused beam of charged particles in the presence of chemically active gases.

A still further object of my invention is to produce chemical compounds by focusing a beam of charged particles on a material which is enveloped by a chemically active gas.

Another object of my invention is to fours a charged particle beam on the surface of a material in the presence of chemically active gas for producing a chemical gas ice

A 2 reaction between said surface and said gas to produce I surface coating of desired properties on the material.

A still further object of my invention is to produce holes of any desired shape in a material by focusing a beam of charged particles on the surface of said materifl in the presence of a chemically active gas whereby the portion of said surface to be drilled has its temperature raised high enough only to initiate a chemical reaction between that portion and the adjacent chemically active As stated above, my novel invention contemplates the passage of a focused beam of charged particles into a gaseous atmosphere whereby a material to be worked is positioned within the gaseous atmosphere. However, it is to be realized that the electron beam is created and focused under a relatively high vacuum having a pressure substantially less than the pressure of the gaseous atmosphere surrounding the body which is to be worked.

In order to prevent contamination of the high vacuum environment of the electron gun structure I have provided a novel intermediate pressure chamber which is interposed between the high vacuum structure of the electron gun and the structure containing the gaseous atmosphere of the material to be worked upon. More specifically, the beam of charged particles, such as electrons, is emitted through a relatively small aperture in its high vacuum housing and into an intermediate pressure chamber which is maintained at as low pressure as possible.

A second chamber is provided for housing the material to be worked in the gaseous atmosphere, this housing also having a relatively small aperture extending into the intermediate pressure chamber and adjacent the aperture in the housing of the beam-emitter. The aperture in the gaseous atmosphere container may be made relatively small so as to substantially, eliminate a flow of gas molecules therethrough and into the gaseous chamber while still being large enough to admit the focused beam of charged particles.

However, a considerable number of gaseous molecules will still escape through the aperture and into the intermediate pressure chamber to interfere with the charged particle beam by collision.

Accordingly, my novel intermediate pressure chamber is further constructed so that the aperture of the housing containing the beam-emitting structure under high vacuum and the aperture of the housing enclosing the gaseous atmosphere and the material with which it is to toact are placed at a distance which is less than the meanfree path of the gas molecules in the intermediate pressure chamber. Thus, random collision between the charged particle beam and gas molecules is substantially eliminated.

This novel use of an intermediate pressure chamber for allowing the flow of charged particles lfi'Ofll a high vacuum environment to an environment of relatively high pressure could be extended by the use ot a plurality of intermediate pressure chambers when the change in pressure is so great as to require the use of more than one intermediate chamber. In this case the distance between apertures of adjacent chambers is again kept less than the mean-free path of a gas molecule therebetween.

Thus, each pressure chamber can have a conical-1y extending section which telescopes into a similar conical extension of an adjacent intermediate chamber whereby the overall axial dimension of the chamber may be kept small.

Furthermore, by constructing at least one of the conically extending sections in an appropriate manner, it could be used as an electromagnetic collector lens for achieving the desired focus of the beam.

Accordingly, an important object of my invention is 3 to provide a novel intermediate pressure means for allowing a beam of charged particles to be emitted from a low vacuum structure and into a relatively high pressure area.

A still further object of my invention is to provide a novel intermediate pressure means for allowing the flow of a charged particle beam from a low pressure area to a relatively high pressure area where the openings of the two pressure areas are spaced from one another by a distance which is less than the mean-free path of molecules within the intermediate pressure chamber.

Another object of my invention is to focus a beam of charged particles on a material surrounded by a gaseous atmosphere to initiate a chemical reaction between the material and the gas wherein an intermediate pressure chamber is utilized to permit the charged particle beam to emerge from a relatively low pressure area and into the relatively high pressure area of the gaseous atmosphere without colliding with gas molecules in the intermediate chamber.

A still further object of my invention is to provide a plurality of adjacently positioned intermediate pressure chambers for allowing a beam of charged particles to be emitted from a relatively low pressure area and to be impinged upon a relatively high pressure area without having the molecules of said relatively high pressure area forced into said relatively low pressure area.

A still further object of my invention is to utilize a plurality of intermediate pressure chambers of the above described type wherein adjacent apertures for passing said beam of charged particles are positioned at a distance which is less than the mean-free path of the molecules between said adjacent apertures.

A still further object of my invention is to utilize intermediate pressure chambers of the above described type wherein said chambers have conically extending portions with an aperture therein, which conical extending portions are telescoped within one another.

A still further object of my invention is to utilize an intermediate pressure chamber of the above described type wherein said intermediate pressure chambers further form an electromagnetic lens for influencing the action of said charged particle beam.

In my above described novel system for utilizing a focused beam of charged particles as a heat source for causing a chemical reaction between a material and a gaseous atmosphere, I have found it desirable to be able to control the heat source in both magnitude of heat at the focus of the beam, as well as the point of application of the heat source to the body being worked upon.

In controlling the magnitude of heat applied to the body immersed in a gaseous atmosphere I have found that I can either control the intensity of the charged particle beam by any of many well known methods, or if desired, I can achieve the same effect by controlling the length of time a charged particle beam of given current density condensity is applied to a particular location.

The point of application of the heat source to the body immersed in a gaseous atmosphere may be controlled either by maintaining the beam stationary and moving the material which is to enter into a chemical reaction with its surrounding gas, or by maintaining the object stationary and deflecting the beam in any of many well known manners as by utilizing electrostatic deflection means or magnetic deflection means or any combination thereof.

1 have found it particularly desirable, however, to utilize a plurality of electromagnetic structures positioned in the chamber containing the gaseous atmosphere wherein selective energization of various of the structures serve to deflect the focused beam of electrons in a desired manner.

Accordingly, another important object of my invention is to provide a focused beam of charged particles for heating a materiai s'tuated in a gaseous atmosphere wherein novel means are provided for controlling the amount of heat generated in the material to be worked by the focused charged particle beam.

Another object of my invention is to control the heat imparted to a material in a gaseous atmosphere by a focused beam of charged particles by controlling the charged particle current.

A still further object of my invention is to provide novel heat control means which includes intermittent energizing means for intermittently controlling the generation of a focused beam of charged particles.

A still further object of my invention is to provide novel heat control means which includes means for moving the focal point of a beam of charged particles with respect to a material positioned at said focal point.

A still further object of my invention is to provide novel heat control means comprising means for causing relative motion between the focal point of a beam of charged particles and a body positioned at said focal point.

A still further object of my invention is to utilize a focused beam of charged particles for heating a material submerged in a gaseous atmosphere wherein said material is movable with respect to said beam.

Still another object of my invention is to provide deflection means for varying the position of the focal point of a beam of charged particles impinging upon a body immerged in a gaseous atmosphere.

A sitll further object of my invention is to impinge a focused beam of charged particles upon a surface of a body immerged in a gaseous atmosphere wherein deflection means for altering the position of said focal point in a direction perpendicular to the axis of said beam are positioned adjacent said material.

In many applications of my novel invention it is desirable that the reaction occurring between the material and its gaseous atmosphere be visually observable. For this purpose I have found it possible to construct a novel telescope means which includes a reflecting surface positioned in the chamber within which the focused electron beam, or charged particle beam, is created and reflects light from the surface of the material being worked to an outer observation point.

Accordingly, another object of my invention is to pro vide novel observing means for observing work material positioned in a gaseous atmosphere and heated by a beam of charged particles.

A still further object of my novel invention is to provide novel visually observing means which includes a reflecting surface positioned in alignment with the material to be worked and the apertures through which the electron beam, or charged particle beam, passes whereby said reflecting surface reflects the image of the material being worked to an external observation point.

These and other objects of my invention will become apparent from the following description when taken in conjunction with the drawings in which:

FIGURE 1 is a cross-sectional view of one embodiment of my novel invention wherein a work piece is immersed in a controlled atmosphere which is isolated from an area of different pressure, and a focused electron beam is impinged thereon.

FIGURE 2 is similar to FIGURE 1 and shows means whereby the work piece may be moved relative to the focused electron beam, and further shows novel means whereby the work piece may be optically. observed during impingement of the electron beam thereon.

FIGURE 3 shows a further application of the structure of FIGURE 1 wherein the electron beam is intermittently controlled for controlling the application of heat to the work surface.

FIGURE 4 is a still further embodiment of my novel invention wherein a novel magnetic structure is utilized to control the point of impingement of the focused electron beam upon the surface of the piece being worked.

FIGURE is a cross-sectional view of FIGURE 4 when taken across the lines 5-5.

FIGURE 6 shows a circuit diagram of the control structure of FIGURES 4 and 5.

FIGURE 7 is similar to FIGURE 1 and illustrates the use of a plurality of intermediate pressure chambers.

Use of controlled atmosphere Referring now to FIGURE 1, a work piece is positioned by a fixture 22 within a controlled atmospheric chamber 24 with the upper surface of work piece 20 exposed to a focused beam of charged particles such as a focused electron beam. In the example to be set forth hereinafter, the work piece 20 will be assumed to be diamond which is to have some desired shaped hole drilled therein, although it is to be understood that this work piece could be of any desired material.

As has been set forth in my copending application Serial No. 257,672, filed November 28, 1951, it is necessary to achieve a temperature of the order of 2,000" centigrade in order to bore a hole in a diamond in a vacuum. However, at this temperature the diamond tends to decompose to graphite and destroys the material adjacent to the desired bored hole.

In accordance with my novel invention I introduce a controlled atmosphere into the chamber 24 which is of such a nature as to chemically combine with the heated material of work piece 20 at a temperature below the required temperature for decomposing the material of work piece 20. Thus, in the instant example where the work piece 20 is of diamond I can introduce oxygen into the chamber 24 in a manner to be hereinafter described and a sharply limited area of diamond 20 is heated to a temperature of the order of 300, at which temperature the carbon of the diamond combines with the oxygen atmosphere to form carbon dioxide or carbon monoxide. Therefore, it is clear that the diamond will have a hole bored therein at this sharply defined area, the crosssection of which is defined by the cross-section of the focused electron beam impinging thereon.

In the specific embodiment of FIGURE 1 an electron gun structure seen generally at 26 which is of the type set forth in my oopending application, Serial No. 258,671, filed Nov. 28, 1951, now Patent No. 2,771,568, and in general comprises a heated cathode 28 which is energized from terminals 30 and 32, and a control electrode 31 which is comprised of a coaxial conical and cylindrical member for imparting a sharp remote focus to the electron beam emitted from the cathode 28. A detailed description of the operation of this structure is set forth in my above noted copending application Serial No. 258,671 and will not be further described herein.

The control electrode 31 is connected to a negative potential at terminal 34, and an anode member 35 which is connected to ground 36a accelerates the electron beam in a manner well known in the art. The entire electron gun structure is housed in a chamber 36 which contains collimating slits 38 and 40 which serve to block scattered electrons and maintain the beam to a small crosssectional area.

As is further set forth in my copending application Serial No. 258,672, filed November 28, 1951, now Patent No. 2,793,281, focusing of the beam is further enhanced by the magnetic structure 41 which comprises a magnetic structure including pole pieces 43, 45, 47 and 49, and the energizing coil 51 which is energized from a D.-C. source (not shown).

A high vacuum is maintained within the chamber 36 by the diffusion pump 44 through the conduit 46 which is fastened to the chamber 36 in any of many well known manners.

The desired controlled atmosphere is introduced into the chamber 2 from a tank 46 through the conduit 48 and valve member 50 which is controlled at the handle 52 in the well known manner. Thus, by controlling valve 50 the amount of gas, such as oxygen, introduced into the chamber is easily controlled.

An exhaust pump 54 then communicates with chamber 24 over the conduit 56 to thereby exhaust the new chemical compound which is formed by the interaction of the controlled atmosphere introduced from the tank 46 and the material of body 20. By way of example, in drilling a hole in a diamond in an oxygen atmosphere, the pump 54 will evacuate the carbon dioxide and carbon monoxide formed during the chemical reaction as well as a surplus oxygen within the chamber 24.

If desired, the new chemical compound formed by the interaction of the controlled atmosphere within the chamber 24 and the work material 20 could be a gas which is diflicult to manufacature by other techniques, and this gas could be collected from the exhaust of vacuum pump 54 schematically indicated as conduit 58, and lead into a reservoir 60 through a valve member 62.

Isolan'on of vacuum system and controlled atmosphere In order to provide the electron beam access to the surface of work material 20 within chamber 24 it is necessary to provide an aperture 64 which is in registry with the focused electron beam. This, however, would normally allow a flow of the molecules of the controlled atmosphere of chamber 24 to flow through aperture 64 and into vacuum chamber 36 through its aperture 42, and obviously in front of aperture 42 and between the apertures 42 and 64. The gas molecules present in these two areas will interact with the electron beam and substantially attenuate the electron beam intensity through collisions between the gas molecules and the electron beam.

In order to avoid this attenuation I have provided a novel intermediate chamber 66 which is positioned between apertures 42 and 64 and is kept under low pressure by the vacuum pump 68 which is connected to intermediate pressure chamber 66 by the conduit 70. The pressure maintained within chamber 66 and the distances between apertures 42 and 64 are so adjusted that the mean-free path ofthe gas molecules within intermediate chamber 66 is greater than the distance between the apertures whereby entrance of gas molecules to the intermediate chamber 66 is substantially eliminated, and the interference of these gas molecules with the electron beam within the intermediate pressure chamber area is negligible. Gas molecules which do escape from chamber 24 and into chamber 36 through the aperture 42 are minimized in their effect on the electron beam since they are rapidly removed by the vacuum pump 44.

It is to be noted that the mean-free path of the gas molecules will be a function of the pressure and the type of gas used.

In one particular embodiment of my novel invention wherein the work material 20 was diamond to be drilled in an oxygen atmosphere, the oxygen in chamber 24 was under a pressure of 19x10" mm. Hg, the pressure of the intermediate chamber 66 being 1X10" mm. Hg, the distance between openings 42 and 64 was approximately about 1 centimeter, and the electrons of the electroln beam had an electron energy of 50,000 electron vo ts.

When the pressure of oxygen within chamber 24 is increased to approximately 50x10 mm. Hg and all other parameters are maintained constant, then the distance between openings 42 and 64 should be reduced to approximately 1 millimeter so as to be less than the mean-free path of the gas molecules under these conditions.

ince it may be desirable to use still higher pressures mean-free pa of the molecules decreases as thy the controlled atmos her cm u ate pressure chamber wou e n orer to operate at increased pressure levels, I provide the structure set forth in FIGURE 7 which is identical to the device of FIGURE 1 in all respects, with the exception of the use of a plurality of intermediate pressure chambers 72, 74 and 76. The intermediate pressure chamber 72 contains the aperture 42 formed by pole pieces 45 and 49 of the electromagnetic focusing structure 41 and the auxiliary lower pole pieces 78 and 80 fastened to wall 82. The aperture formed by pole pieces 78 and 80 contains a small tube 83 of non-ferromagnetic material which contains an aperture therein (not shown) for allowing passage of the focused electron beam. A second pressure chamber 74 is formed by a wall 82 and pole pieces 78 and 80 and the lower wall 84 which has a conical central extension containing aperture 86. The third pressure chamber is then formed by the walls 84 and a lower wall 88 which is the upper wall of chamber 24 containing the aperture 64. Hence, three pressure chambers 72, 74 and 76 are defined and are connected through conduits 90, 92 and 94 to appropriate vacuum pump means (not shown) which can maintain their respective intermediate pressure chambers at some predetermined pressure.

It is to be noted that the aperture of each of the intermediate pressure chambers is contained within a conically extending portion, and each of these conically extending portions are telescoped into one another so that their separation may be adjustably controlled and still allow a substantial volume for their chambers.

In preventing the relatively high pressure of the controlled atmosphere within chamber 24 from passing molecules into the intermediate pressure chambers and thereby interfering by collision with the electron beam, the distance between adjacent apertures of any of the chambers are made. to be less than the mean-free path of the gas within that chamber in the manner identical to that described above for the single intermediate pressure chamber 66 of FIGURE 1. That is to say, the distance between apertures 64 and 86, and apertures 86 and 82, and apertures 82 and 42 are adjusted to be less than the mean-free path of the molecules interposed between hese apertures.

In a typical embodiment, where it is desired to bore a hole of 0.1 millimeter in diameter in an oxygen atmosphere, a beam current intensity of 0.2 milliampere and an electron energy of 50,000 electron volts was utilized. The oxygen pressure within chamber 24 was varied between l mm. Hg to normal atmospheric pressure while the chamber 72 was kept at about 1X10" mm. Hg, chamber 74 was kept to 10X 10- mm. Hg and chamber 76 was kept to 1,000X10' mm. Hg. Obviously, the distances between the various apertures need only be less than the mean-free path of the gas molecules which can be easily computed from these values.

While my novel invention has been described hereinbefore in conjunction with the drilling of a hole in the diamond, it is to be understood that this is only one application of my novel invention which is directed to the use of a focused beam of charged particles as a heat source for initiating a chemical reaction between two materials. Thus, the work piece 20 of FIGURES 1 or 7 could be an iron-silicon alloy which is to have a protective coat placed on any desired portion of the surface area of the material. In this case, the atmosphere within chamber 24 could once again be an atmosphere of oxygen whereupon the silicon of the alloy will enter into a chemical reaction with the enveloping oxygen gas atmosphere to form a surface coat of silicon dioxide which would be highly resistant to various types of acids, and presents other desirable surface protective features. In order to initiate this reaction, it is necessary to raise the temperature at the point of impingement of the focused electron beam upon the surface of the iron-silicon alloy filament to approximately 1,200 C.

I have found that this can be easily accomplished when working the iron-silicon alloy in an oxygen atmosphere of 1 10- mm. Hg to atmospheric pressure, the beam current intensity being 10 milliamperes, the electron energy being 60,000 electron volts, and the beamed diameter being 1 millimeter at the point of impingement.

Clearly, after the desired protective coating is formed at a first portion of the surface, the work material may be moved to expose a new surface area to the beam, and in this manner any desired portion of the surface of the iron-silicon work material 20 may be coated. Means by which relative movement may be effected between the electron beam and the work body will be more fully described hereinafter.

A still further example of an application of my novel invention is in the boring of a material such as titanium. In the past, when it was attempted to bore small holes in titanium, it was required to heat the area to be bored to approximately 2,000 C. When this heat was applied to a local area, adjacent portions of the area to be bored were subjected to considerable heat due to the conductivity of the material and the surrounding portions of the hole to be bored were melted, thereby obviating the boring of a clean, well-defined hole.

In accordance with the instant invention, I have found that I can bore titanium in the presence of a chlorine atmosphere in a manner similar to that described in the boring of a diamond in an oxygen atmosphere. That is to say, titanium will combine with chlorine at 300' C. to form titanium chloride which evaporates at approximately C. Clearly, therefore, a clean hole will be chemically formed with the application of my novel invention to the drilling of titanium. I have drilled holes in titanium material in accordance with the above noted method by accelerating an electron beam to an energy of 60,000 electron volts and applying this beam to the surface of a titanium material for 10- seconds. During this time the surface of the material was raised to 500' C. and, as above stated, the titanium entered into a chemical reaction with the chlorine atmosphere at that point whereby titanium chloride is formed and is immediately volitalized to result in the drilling of a hole having distinctly defined borders in a very short time.

As it will be set forth hereinafter, I can obtain this type of operation with an impulse system for pulsing the electron beam on a material to be drilled whereby the electron beam is impinged for a predetermined time upon a local area and is thereafter turned off and the beam and the surface of the material are moved with respect to one another, whereupon the beam is again turned on to drill another hole, this process being continued in accordance with a predetermined schedule.

In general, I have found that when boring material having a heat conductivity of 0.1 to 0.2 calorie per centimetersecond C.. impulses having a duration of the order of 10- to 10- seconds are suflicient to obtain a fast boring with the assurance of sharp, well defined holes. However, this duration of application of focused electron energy is varied in accordance with the particular characteristics of the material being worked.

Control of application of heat source As is apparent from the above discussion, it is desirable to be able to control the application of the focused electron beam to a surface for obtaining the control of the amount of heat applied to a particular surface point or to move the application of heat from point to point along the surface.

In the latter case, the heat source may be applied to various points along the surface of the material by moving the work piece with respect to the focused beam.

Thus, in FIGURE 2, which is based on FIGURE 1, fixture 22 which supports work material 20 is movable in a plane perpendicular to the axis of the electron beam by means of the crank arrangement including screw 100 attached to crank 102 and a similar threaded member which engages tapped aperture 104 of table 106 which is slidably mounted to bottom wall 108 of chamber 24. More specifically, screw member 100 penetrates the side wall of chamber 24 through the gasket means 110 and threadably engages a member 22 which is guided in a linearly grooved member 112 fastened to member 106. Hence, a rotation of crank 102 will cause the table 22 to move to the left or right of the axis of the electron beam.

A crank member, not shown, which is arranged externally of the chamber 24 may be then operated to drive table 106 in a direction into or out of the paper with the threads of screw member, not shown, which engages tapped aperture 104 of table 106. Hence, the material 20 to be worked may be positioned in any desired manner with respect to the focused electron beam.

It is to be understood that this method of adjusting the position of work piece 20 with respect to the electron beam is merely illustrative and many other systems mechanical or otherwise could be utilized.

While the work piece may be moved relative to the electron beam, it is, of course, possible to achieve relative motion between the beam and the work piece by maintaining the work piece stationary and moving the beam.

One embodiment of this type of arrangement is set forth in FIGURES 4, and 6 wherein FIGURES 4 and 5 are identical to the device of FIGURE 1, with the exception of a beam position control structure. This beam control structure is best seen in FIGURES 4 and 5 as being positioned within the chamber 24 and comprising four coils 114, 116, 118 and 120 which are wound on extending legs 122, 124, 126 and 128 respectively of the magnetic ring structure 130. Each of the legs 122 through 126 extends inwardly and toward the central ring 132 which is constructed of non-magnetic material and forms an aperture through which the electron beam may pass into an area containing the material to be worked.

The electrical connection diagram for coils 114 through 120 is set forth in FIGURE 6 where it is seen that coils 114 and 118 are connected in series and are energized from potentiometer 134 which is connected across secondary winding 136 which is energized from primary winding 138. In a similar manner winding 116 and 120 are connected in series and energized from potentiometer 140 which is connected across secondary winding 142 which is energized from the same primary winding 138.

In view of the above described connection, it is clear that a rotating magnetic field will be set up in the area through which the electron beam passes through the magnetic legs 122 through 128, and the point of impingement of the focused electron beam upon the surface of material 20 will be varied accordingly.

By way of example, potentiometers 134 and 140 could be energized in phase quadrature and adjusted so that the same current flows in each of the coils whereby the rotating magnetic field will force the charged particle beam to describe a circle around the surface of the material to be worked.

Clearly, any type path could be imparted to the focal point of the charged particle beam.

As has been previously discussed, it may be desirable to apply beam energy in an impulse form to achieve a control of the amount of heat supplied to a particular surface area. FIGURE 3 sets forth one type of impulse control circuit that could be applied to any control electrode structure and specifically to a control electrode structure which controls the impingement of a beam of electrons upon a material which is to be heated.

The electron gun structure of FIGURE 3 which is used for illustrative purposes comprises a heated cathode 144 which is energized from terminals 147 and 148. The beam of charged particles emitted from heated cathode 144 is controlled by the control electrode 146 which could 10 be socalled wehnelt cylinder and having an aperture 14 therein. The beam is then collimated by slits 150, 152 and 156 and focused by magnetic structure 156, and is introduced into a chamber 158 which contains the ma terial to be worked.

In order to produce a controlled train of impulses to flow from heated cathode 144, I have provided novel control circuitry for controlling the potential applied to the control electrode 146. This novel circuitry includes the multi-vibrator system which includes electron tubes 160 and 162 which have a common cathode resistor 164. The grid of tube 160 is connected to ground 166 through the grid leak resistor 158, while the grid of tube 162 is connected to ground 166 through the grid leak resistor 168. Each of tubes 160 and 162 are further provided with plate resistors 170 and 172 respectively, and plate potential for each of tubes 160 and 162 is applied between the terminals 174 and 176, the potentials being those shown in the figure.

Anode potential for the electron gun structure is taken from a high voltage source and is applied to terminal 178 and through current limiting resistor 180 and capacitor 182 to ground 184. This same high voltage is applied to the terminal 147 and has superimposed upon it a D.-C. bias voltage from the controllable D.-C. bias source 186, the potentials being those shown in the drawing whereby control electrode potential would normally be slightly more negative than the potential of cathode 144 by an amount given by the voltage of the D.-C. bias source 186.

As is well known in the art, gn'd leak resistances 158 and 168 will control the operation of the multi-vibrator circuit so far as alternate conduction of tubes 160 and 162 is concerned. Thus, grid leak resistor 158 will control the length of time that the electron beam will be turned off, while grid leak resistor 168 will control the time that the electron beam will be on. For when'current flows through the tube 162 a positive voltage impulse due to the current flow through plate resistor 172 will be superimposed upon the potential of control electrode 146 (which is normally biased to cut-off by the high voltage supply at terminal 178 and bias source 186) to unblock the cathode and allow an electron beam to flow until such time as tube 162 of the multi-vibrator circuit is cut off and tube 160 conducts.

It is to be noted that my novel use of the capacitor 182 improves the operation of this circuit since this capacitor is charged during the time that the electron beam is cut off and discharges when a voltage impulse is applied to the control electrode 146 to thereby impart sharp operating characteristics to the initiation of the electron beam impulse.

Observation of work piece during impingement of electron beam There are applications where it is highly desirable to observe the work piece so as to correct the alignment thereof before or after impingement of an electron beam thereon as well as to observe the process of the chemical reaction as it takes place. To this end I have provided a novel optical system, as set forth in FIGURE 2, which comprises a reflecting surface 190 which is positioned immediately adjacent to the electron beam path and is at an angle to reflect light rays which extend from the portion of the material being worked through the aperture 192 in the wall of chamber 36 and beneath the magnetic focusing structure 41 and on to an optical system seen generally at 194. Optical system 194 includes the positive lens 196 and the optical viewing system 198 having an eye-piece 200 which could be exposed to photographic means or to a human observer.

It is to be noted that an auxiliary light source (not shown) could be positioned within the chamber to scatter light from the object to be worked into the eye-piece 200 for adjustment of the work material before or after im- 1 1 pingernent of the electron means. However, during the working of the material the light of the chemical reaction taking place could be directly observed in the absence of any other light source.

Although I have described preferred embodiments of my novel invention, many variations and modifications will now be obvious to those skilled in the art, and I prefer therefore to be limited not by the specific disclosure herein but only by the appended claims.

I claim:

1. Apparatus for initiating a chemical reaction between a first and second material; said apparatus comprising a first relatively gas tight chamber; said first relatively gas tight chamber having said first material supported therein and having means for introducing a gaseous atmosphere containing said second material into said first chamber at controlled pressure; a second relatively gas tight chamber for supporting a source of a beam of charged particles; a first aperture in' said first pressure chamber for admitting said beam of charged particles into said first pressure chamber to impinge on said first material to initiate a chemical reaction betwen said first and second materials to form a third material, and a second aperture in said second pressure chamber for allowing the exit of said beam of charged particles therefrom spaced from said first aperture; an intermediate pressure chamber ineluding said first and second apertures in the walls thereof maintained at a pressure lower than the pressure of said first chamber, the distance between said first and second apertures being less than the mean-free path of gas molecules within said intermediate pressure chamber.

2. A first housing for supporting a first material therein; said first housing having a gaseous atmosphere containing a second material; a second housing for supporting a source of a beam of charged particles to be impinged upon said first material to initiate a chemical reaction between said first and second materials; the pressure within said second housing being lower than the pressure within said first housing; a first and second aperture within said first and second housing respectively for allowing passage of said electron beam from said second housing to the interior of said first housing, and an intermediate pressure chamber positioned betwen said first and second chambers; said first and second apertures being contained in the walls of said intermediate pressure chamber and spaced at a distance less than the mean-free path of gas molecules within said intermediate pressure chamber.

3. In apparatus for initiating a chemical reaction between a first and second material comprising a first chamber having said first material supported therein, means for introducing said second material in a gaseous form into said first chamber at a first pressure, a second chamber for supporting structure therein for producing a beam of electrons focused at a remote point and maintained at a second pressure, a first aperture in said first chamber for admitting said focused beam of electrons into said first chamber with the focused point of said electron beam focused on said first material to serve as a heat source for initiating said chemical reaction, and a second aperture in said second chamber for passing said beam of electrons; an intermediate pressure chamber and means for maintaining said intermediate pressure chamber at a third pressure; said intermediate pressure chamber including said first and second apertures in the walls thereof spaced apart from one another by a distance less than the meanfree path of gas molecules within said intermediate pressure chamber.

4. Apparatus for initiating a chemical reaction between a first and second material; said apparatus cornprising a first relatively gas tight chamber; said first relatively gas tight chamber having said first material supported therein, means for introducing a gaseous atmosphere containing said second material into said first chamber at controlled pressure; a second relatively gas tight chamber for supporting a source of a beam of charged particles; a first aperture in said first pressure chamber for admitting said beam of charged particles into said first pressure chamber to impinge on said first material to initiate a chemical reaction between said. first and second materials to form a third material, and a second aperture in said second pressure chamber for allowing the exit of said beam of charged particles therefrom spaced from said first aperture; an intermediate pressure chamber including said first and second apertures in the walls thereof maintained at a pressure lower than the pressure of said first chamber, the distance between said first and second apertures being less than the meanfree path of molecules of said gaseous atmosphere; said third material being removable from said first material to leave a hole in said first material, said hole having a cross-section defined by the cross-section of said charged particle beam at said focused point.

5. Apparatus for initiating a chemical reaction between a first and second material; said apparatus comprising a first relatively gas tight chamber having said first material supported therein, means for introducing a gaseous atmosphere containing said second material into said first chamber at controlled pressure, and a second relatively gas tight chamber for supporting a source of a beam of charged particles; a first aperture in said first pressure chamber for admitting said beam of charged particles into said first pressure chamber to impinge on said first material to initiate a chemical reaction between said first and second materials to form a third material; said third material forming a surface coat on said first material of a predetermined nature; and a second aperture in said second pressure chamber for allowing the exit of said beam of charged particles therefrom spaced from said first aperture; an intermediate pressure chamber including said first and second apertures in the walls thereof maintained at a pressure lower than the pressrn'e of said first chamber, the distance between said first and second apertures being less than the mean-free path of molecules of said gaseous atmosphere.

6. In apparatus for initiating a chemical reaction between a first and second material comprising a first chamber having said first material supported therein, means for introducing said second material in a gaseous form into said first chamber at a first pressure, a second chamber for supporting structure therein for producing a beam of elearons focused at a remote point and maintained at a second pressure; said structure comprising a source of electrons, a control electrode connectible to a source of control potential and anode means for accelerating said electrons toward said focused point, said control electrode being constructed to produce equipotential surfaces shaped for first diverging said electrons emitted from said source of electrons and thereafter converging said electrons to a focus; a first aperture in said first chamber for admitting said focused beam of electrons into said first chamber with the focused point of said electron beam focused on said first material to serve as a heat source for initiating said chemical reaction, and a second aperture in said second chamber for passing said beam of elem trons; an intermediate pressure chamber and means for maintaining said intermediate pressure chamber at a third pressure; said intermediate pressure chamber including said first and second apertures in the walls thereof spaced apart from one another by a distance less than the meanfree path of gas molecules within said intermediate pressure chamber.

7. In apparatus for initiating a chemical reaction between a first and second material comprising a first chamber having said first material supported therein, means for introducing said second material in a gaseous form into said first chamber at a first pressure, a second chamber for supporting structure therein for producing a beam of electrons focused at a remote point and maintained at a second pressure, a first aperture in said first chamber for admitting said focused beam of electrons into said first chamber with the focused point of said electron beam focused on said first material to serve as a heat source for initiating said chemical reaction, and a second aperture in said second chamber for passing said beam of electrons; a plurality of intermediate pressure chambers interposed between said first and second chambers; each of said plurality of intermediate pressure chambers including aperture means interposed between and in aligmnent with said first and second apertures; the distance between adjacent apertures being less than the mean-free path of gas molecules in the intermediate pressure chamber including said adjacent apertures.

8. A first housing for supporting a first material therein; said first housing having a gaseous atmosphere containing a second material; a second housing for supporting a source of a beam of charged particles to be impinged upon said first material to initiate a chemical reaction between said first and second materials; the pressure within said second housing being lower than the pressure within said first housing; a first and second aperture within said first and second housing respectively for allowing passage of said electron beam from said second housing to the interior of said first housing; a plurality of intermediate pressure chambers interposed between said first and second chambers; each of said plurality of intermediate pressure chambers including aperture means interposed between and in alignment with said first and second apertures; the distance between adjacent apertures being less than the meanfree path of gas molecules in the intermediate pressure chamber including said adjacent apertures.

9. In apparatus for initiating a chemical reaction between 8 first and second material comprising a first chamber having said first material supported therein, means for introducing said second material in a gaseous form into said first chamber at a first pressure, a second chamber for supporting structure therein for producing a beam of electrons focused at a remote point and maintained at a second pressure, a first aperture in said first chamber for admit-ting said focused beam of electrons into said first chamber with the focused point of said electron beam focused on said first material to serve as a heat source for initiating said chemical reaction, and a second aperture in said second chamber for passing said beam of electrons; a plurality of intermediate pressure chambers interposed between said first and second chambers; each of said plurality of intermediate pressure chambers including aperture means interposed between and in alignment with said first and second apertures; the distance between adjacent apertures being less than the mean-free path of gas molecules in the intermediate pressure chamber including said adjacent apertures; the portion of the walls of said plurality of intermediate pressure chambers containing said aperture means being conically formed and positioned in telescoping relationship with one another.

10. Apparatus for initiating a chemical reaction between a first and second material; said apparatus including a first relatively gas tight chamber; said relatively gas tight chamber having said first material supported therein, means for introducing a gaseous atmosphere containing said second material into said first chamber at controlled pressure, and a second relatively gas tight chamber for supporting a source of a beam of charged particles; a first aperture in said first pressure chamber for admitting said beam of charged particles into said first pressure chamber to impinge on said first material to initiate a chemical reaction between said first and second materials to form a third material, and a second aperture in said second pressure chamber for allowing the exit of said beam of charged particles therefrom spaced from said first aperture; an intermediate pressure chamber including said first and second apertures in the walls thereof maintained at a pressure lower than the pressure of said first chamber, the distance between said first and second apertures being less than the mean-free path of gas molecules within said intermediate pressure cham- 14 ber; and means for controlling the heat applied to said first material by said beam of charged particles by controlling the length of time said beam impinges on-sard first material.

11. Apparatus for initiating a chemical reaction between a first and second material; said apparatus comprising a first relatively gas tight chamber having said first material supported therein, means for introducing a gaseous atmosphere containing said second material into said first chamber at controlled pressure, and a second relatively gas tight chamber for supporting a source of a beam of charged particles; a first aperture in said first pressure chamber for admitting said beam of charged particles into said first pressure chamber to impinge on said first material to initiate a chemical reaction between said first and second materials to form a third material, and a second aperture in said second pressure chamber for allowing the exit of said beam of charged particles therefrom spaced from said first aperture; an intermediate pressure chamber including said first and second apertures in the walls thereof maintained at a pressure lower than the pressure of said first chamber, the distance between said first and second apertures being less than the mean-free path of gas molecules within said intermediate pressure chamber; and means for controlling the heat applied to any point of said first material at the focus of said beam of charged particles comprising charged particle control means for moving the focus point of said charged particle beam with respect to said first material.

12. Apparatus for initiating a chemical reaction between a first and second material; said apparatus comprising a first relatively gas tight chamber having said first material supported therein, means for introducing a gaseous atmosphere containing said second material into said first chamber at controlled pressure, and a second relatively gas tight chamber for supporting a source of a beam of charged particles; a first aperture in said first pressure chamber for admitting said beam of charged particles into said first pressure chamber to impinge on said first material to initiate a chemical reaction between said first and second materials to form a third material, and a second aperture in said second pressure chamber for allowing the exit of said beam of charged particles therefrom spaced from said first aperture; an intermediate pressure chamber including said first and second apertures in the walls thereof maintained at a pressure lower than the pressure of said first chamber, the distance between said first and second apertures being less than the mean-free path of gas molecules within said intermediate pressure chamber; and means for controlling the heat applied to any point of said first material at the focus of said beam of charged particles comprising charged particle control means for moving the focus point of said charged particle beam with respect to said first material; said control means comprising a magnetic structure surrounding said beam and windings associated with said magnetic structure controllably energizable to set up magnetic flux across the path of said beam to thereby controllably alter the path of said beam and the focus point thereof; said magnetic structure comprising a magnetic ring having four inwardly extending legs substantially displaced from one another; said windings comprising a winding for each of said legs; the windings of diametrically opposed legs being energized in series to produce said magnetic flux across said path of the beam, said magnetic flux being varied responsive to variation of energization between pairs of said diametrically positioncd windings.

13. In an apparatus containing a first and second material; said first and second material being characterized by entering into a chemical reaction when temperature is raised above a predetermined value; said first material being homogeneous; said Second material being homogeneous; a heat source for elevating the temperature of a sharply defined small area containing both said first and second materials; means for creating and focusing a beam of electrons; said heat source comprising the concentrated energy at the focused point of said focused beam of electrons; said focused point being adjusted to fall on said sharply defined small area to initiate a chemical reaction between said first and second materials within said area; said beam of focused electron being created by electrode structure means comprising a source of electrons, a control electrode connectible to a source of control potential and anode means for accelerating said electrons toward said focused point; and means for intermittently controlling said beam to control the heat applied to any area of the surface of said first material; said means for creating and focusing said beam of electrons being contained in a first chamber; said first and second materials being contained within a second chamber; said first and second chambers having adjacently positioned respective apertures aligned with said beam of electrons; said respective apertures being spaced from one another by a distance less than the mean-free path of gas molecules between said respective apertures.

14. In an apparatus containing a first and second material; said first and second material being characterized by entering into a chemical reaction when temperature is raised above a predetermined value; said first material being homogeneous; said second material being homogeneous; a heat source for elevating the temperature of a sharply defined small area containing both said first and second materials; means for creating and focusing a beam of electrons; said heat source comprising the concentrated energy at the focused point of said focused beam of electrons; said focused point being adjusted to fall on said sharply defined small area to initiate a chemical reaction between said first and second materials within said area; said beam of focused electrons being created by electrode structure means comprising a source of electrons, a control electrode connectible to a source of control potential and anode means for accelerating said electrons toward said focused point; and means for intermittently controlling said beam to control the heat applied to any area of the surface of said first material; said means for creating and focusing said beam of electrons being contained in a first chamber; said first and second materials being 16 contained within a second chamber; said first and second chambers having adj acently positioned respective apertures aligned with said beam of electrons; said respective apertures being spaced from one another by a distance less than the mean-free path of gas molecules between said respective apertures; said control means including means for alternately varying said source of control potential between cut-ofi and beam conduction potential.

15. In combination; a first chamber at a relatively high pressure, a second chamber at a relatively low pressure; and pressure chamber means for permitting the transmission of a beam of charged particles from said second chamber to said first chamber; said second relatively low pressure chamber having a source of charged particles therein and focusing means for directing the charged particles of said source of charged particles toward said second chamber; said first and second chambers being positioned adjacent one another; a first aperture in said first pressure chamber for admitting said beam of charged particles in said first pressure chamber, and a second aperture in said second pressure chamber for allowing the exit in said beam of charged particles therefrom; said first aperture being spaced from said second aperture; an intermediate pressure chamber including said first and second apertures in the walls thereof maintained at a lower pressure than the pressure of said first chamber and at a higher pressure than the pressure of said second chamber; the distance between said first and second apertures being less than the mean-free path of gas molecules within said intermediate pressure chamber.

References Cited in the file of this patent UNITED STATES PATENTS 1,556,325 Grumpelt Oct. 6, 1925 2,267,714 Borries et al Dec. 30, 1941 2,267,752 Ruska et a1. Dec. 30, 1941 2,345,080 Ardenne Mar. 28, 1944 2,423,729 Ruhle July 8, 1947 2,429,217 Brasch Oct. 21, 1947 2,543,710 Schmidt et a1. Feb. 27, 1951 2,591,460 Mon-ill Apr. 1, 1952 2,778,926 Schneider Jan. 22, 1957

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