US2712073A

US2712073A - Temperature control

Info

Publication number: US2712073A
Application number: US561271A
Authority: US
Inventors: Emmett V Martin
Original assignee: Individual
Current assignee: Individual
Priority date: 1944-10-31
Filing date: 1944-10-31
Publication date: 1955-06-28
Anticipated expiration: 1972-06-28

Description

Jfine 28, 1955 MARTIN 2,712,073

TEMPERATURE CONTROL Filed Oct. 51, 1944 32 INVENTOR.

4'0 'nzmeif amariz'n BY Ma M 14 1r 16 Kai-E M r X United States Patent TEMPERATURE coNTRoL Emmett V. Martin, Oak Ridge, Tenn., assignor, by mesne assignments, to the United States of America as represented by the United States Atomic Energy Com- IIllSSlOll Application October 31, 1944, Serial No. 561,271

12 Claims. (Cl. 250-419) The invention described herein relates to the field of isotope separation, that is separation of ions having different mass-energy properties. It is particularly concerned with equipment wherein the ion source includes means for volatilizing a material to be ionized by the controlled application of heat to the material.

Heretofore in equipment of this nature it has been the practice to volatilize the material to be ionized, and to maintain the material in a vapor state by the applicaitself, which, as mentioned, includes a relatively high intensity electron stream for bombarding the vapor of the volatilized charge, constitutes a relatively unsteady source of considerable heat, and since this heat may be quite readily conducted to the charge itself, it becomes difiicult to accurately maintain the temperature of the charge. An object of my invention is to meet the difficulty by employing an automatic control system having a thermostatic means so located, with reference. to the structure, that the thermostatic means is affected by heat from the ionizing means to the same extent that the charge being volatilized is atfected thereby. Thus the thermostatic means is able to dampen out variations of the temperature of the charge which would otherwise result from heat conducted thereto from the ionizing means.

Another object of my invention is to supply heat to the vaporized charge in the vicinity of the ionizing means to maintain it in a vaporized state and to control this heat in response to the thermostatic means which controls the main heat for volatilizing the charge. preferred form of the invention, the heating means which provide heat for volatilizing the charge and for maintaining the charge in a vapor state in the vicinity of the ionizing means are electrical heating elements connected in parallel.

Other objects and advantages of my invention will become apparent from the following detailed specification and annexed drawings, wherein:

Fig. 1 is a diagrammatic view of an isotope separator including an ion generator in which the control arrangement of my invention may be practiced.

Fig. 2 is a view of the control arrangement of my invention applied to an ion producing source of the type which may appropriately be used in the system of Fig. 1.

Referring to Fig. 1 of the drawings, there is shown diagrammatically an apparatus for isotope separation, the apparatus including ion generating means wherein a solid material is volatilized by the application of heat, my invention being particularly adapted to the control of the application of heat for volatilizing the material and thereafter maintaining it in a vapor state during ionization. The'apparatus of Fig. l is of the type disclosed in greater In the 2,712,673 Patented June 28, 1955 'ice detail in the application of Ernest 0. Lawrence, Serial No. 557,784, filed October 9, 1944. The apparatus of Fig. 1 includes a tank 10 the interior of which is evacuated to a relatively high degree of vacuum as will be presently explained. The tank 10 is rectangular in cross section, and one side of the tank is closed by a relatively heavy face plate 11 which is attachable to the tank by means of

screw clamps

12 and 13, there being provided suitable bearing surfaces on the face plate 11 and on the tank 10 so that when the face plate 11 is clamped in position, it engaged the tank in sealing relationship so as to insure against loss of vacuum at the joint. All of the mechanism within the tank 10 is attached to and carried by the face plate 11 as will be presently explained.

The tank 10 has a number of windows 14, 15, 16, and 17, so as to make it possible to watch operations within the tank, and it has a large discharge outlet through which the air and moisture within the tank are evacuated. The discharge outlet 20 is connected to dilfusion pumps, indicated diagrammatically at 21, by a suitable connection, asshown, and the difiusion pumps 21 are backed by, that is connected to, a mechanical pump or pumps 22, these pumps being of the rotary type. They may be Kinney pumps for example.

Within the tank 10 is a liner structure 23 which forms an arcuate conduit for a beam or beams of ions generated at the left end of the liner and terminating adjacent the right end thereof. The liner 23 and its associated apparatus is carried from the face plate 11 by the supporting structure, designated generally by the

numerals

24 and 25, and by the brace indicated by numeral 26.

Adjacent the left end of the liner 23 are disposed a pair of volatilizing chambers and 31 in which a charge of solid material to be ionized is volatilized. My invention is primarily concerned with the control of the application of heating to the

chambers

30 and 31, the chamber 30 with its associated heating elements and automatic control therefor being shown in greater detail in Fig. 2. Since the two chambers and their associated equipment are identical, only one will be described in detail.

Referring now more particularly to Fig. 2, the chamber 30 may preferably be generally cylindrical. It includes a lower portion 32 and a smaller upper portion or chamber 33 connected to the lower portion by a diverging passageway or throat 34. Numeral 35 designates a charge bottle adapted to contain a charge of the solid material to be volatilized and shaped so as to fit within the lower part 32 of chamber 30. The charge bottle 35 has an opening 36 in its top through which the volatilized material may pass upwardly. The upper chamber portion 33 has a bottom 37 with spaced openings 38 and 39 therein to allow the vapor to pass up into the portion 33. Extending across the interior of the chamber portion 33 is a plate or baffle 40 having

openings

41 and 42 near its edges to permit the upward travel of the volatilized charge. The chamber portion 33 also has an opening 43 in its top in the form of a relatively long and narrow slit, and the vapor from the volatilized charge passes upwardly through this slit. Near one end of the slit 43, and adjacent a slit 45, is a filament 44 to which a suitable voltage is applied for heating it, as will presently be described, and from which electrons are emitted near the end of the slit 43. The filament and its operation will be referred to presently.

The lower portion 32 of chamber 30 is heated by an electric heating element and the upper portion is heated by another electric heating element 51. The operation of the electric heaters and the automatic controls therefor will be described presently.

Referring again to Fig. 1, above the chamber 30 and adjacent thereto is a member 52. which may preferably be I made of carbon, and which has therein a slit 53 which is directly above and parallel to the slit 43 of chamber portion 33. The member 52 is electrically connected to a similar member above the chamber 31, the apparatus associated with the two chambers being identical as previous ly pointed out. The member 52 constitutes an electrode which is maintained at a certain potential, as will presently be described, for accelerating a beam of ionized particles passing upwardly through the slit therein. Above the member 52 is a conical throat-shaped member 54 through which the beam passing upwardly through the slits 53 and 43 passes into the liner 23.

The entire tank is disposed within a relatively intense magnetic field produced. by windings indicated diagrammatically at 57 which completely encircle the tank and liner as indicated, the direction of the field being perpendicular to. the. plane of. the drawing. The direction of the field is therefore parallel to the slits 43 and 53.

The face plate 11 is grounded as shown and the liner 23 and the members 52 are maintained at relatively high negative potentials by conductors which are fed into the interior of the tank It through a conduit 58 which extends through a sealing device 59 in face plate 11. The liner 23 is maintained at a relatively high negative potential V1 by means of a conductor 60, and the member 52 is maintained at a relatively high negative potential V1+V2, which is higher than the potential of liner 23, by means of a conductor 61. The operation of the ion generating apparatus as so far described is that the vapor of the volatilizing charge in the bottle passes upwardly into the chamber portion 33 where it is maintained in vapor state by the electric heating element 51, the vapor then passing upwardly through the slit 43. Energization of the filament 44 causes electrons to be emitted therefrom, which electrons are collimated to form a beam in the slit 43 by the action of the magnetic field, which, as has been previously described, is in a direction to the slit. The electrons bombard the particles of the vapor passing upwardly through the slit 43 so as to form ions which are accelerated upwardly in the form of a beam through the slit 53 in the electrode 52, which, as described above, is maintained at a relatively high negative accelerating potential. The beam of ions passes upwardly through the throat 54 and the effect of the magnetic field upon the beam is to bend it into an arc of a circle within the liner 1.3, the beam traveling around through the liner so as to be received in a receiving chamber adjacent the right end of the liner 23. The receiving chamber 65 is in the form of a box having a shape which in cross section is as shown in Fig. l. The receiver 65 may be adjusted laterally by stem 66 operating through linkages 67 and it may be adjusted vertically by a stem 68, the stems passing through suitable sealing devices 69 and 7 0, respectively, associated with the face plate 11. The receiver 65 has

pockets

71 and 72 therein which are so located as to receive certain components of the beam which travels around through the liner 23, it being understood that various components of the beam travel in arcs of circles of different radii depending upon the mass-energy properties of the different components. Within the

pockets

71 and 72 are electrodes 73 and 74, respectively, which are maintained at the negative potential V1 by means of conductors 75 and 76 which are led out of the tank 10 through a conduit 77 similar to the conduit 58, the conduit 77 passing through the face plate 11 byway of a sealing device 78 associated with the face plate. The electrodes 73 and 74 are at the point of focus of the components of the beam which it is desired to collect, the desired isotopes collecting in the

pockets

71 and 72 during operation.

Numeral 81 designates a manually operated shutter which may be moved to a position in front of the window 17 by means of an operating stem 82 extending through a sealing device 83.

It will be understood, of course, that those elements Cir which are maintained at high potential are suitably insulated from other elements at lower or ground potential. Also as described in the application previously referred to, various of the parts within the tank It may be cooled by a suitable water cooling system, and shielding may be provided at appropriate points to protect the mechanism from becoming coated as a result of being contacted by the vapor from the charge bottle and for protection from deterioration which may necessarily result from the process.

In carrying out the ionizing and isotope separating process, it is necessary that the charge bottle 35 be maintained accurately at a temperature within 2 of the desired volatilizing temperature. The chamber portion 33 must be maintained at a relatively higher temperature, sufficiently high so as to maintain the material within the chamber portion 33 in a vapor state so that it can be appropriately ionized by bombardment of the electron stream. The electric heating elements 50 and 51 are connected in parallel, as shown, and to the secondmy 85 of a transformer 86 having a primary winding 87. The electric heating elements 50 and 51 may be of the well known Calrod type and are of sufficient heating, capacity so as to produce the required heating in. the

.;

chamber portions

32 and 33. Both of the electric heating elements are controlled by a control system which includes, as the primary control element, thermocouple 88. situated in the throat 34 so that it is affected by heat produced by both of the electric heating elements 50 and 51. That is, the thermocouple 88, which is suitably shielded, responds to a temperature at a point in the temperature gradient across throat 34, it being remembered that the chamber portion 33 is maintained at a higher temperature than the chamber portion 32, the relative capacities of the heating elements being such as to cause a higher temperature to be maintained in the chamber portion 33. The beam of electrons or are, which has been described with reference to slit 43, and the accelerating electrode 52 generate a considerable amount of heat, and this source of heat during operation is relatively unsteady. This heat can be transferred to the charge in the charge bottle quite readily by conduction. It is an object of my arrangement therefore to prevent this heat from changing the temperature of the charge inthe charge bottle without the thermostatic element 88 being similarly affected. The position of the thermocouple 88 is therefore such that the heat from the ionizing means affects the thermocouple and the charge in the charge bottle substantially similarly. The thermocouple 88 is, therefore, able to control the temperature at the charge bottle with accuracy even though the heat generated by the ionizing means is unsteady.

The control system which I prefer to use includes a potentiometer device 89 which is automatically adjusted in accordance with the amount that the temperature affecting thermocouple 88 deviates from a set value. The device 89 may preferably be the instrument known as the Micromax manufactured by the Leeds & Northrup Company. The device 89 impresses a voltage signal upon an electronic control device 90 which may appropriately be the Reactrol control device manufactured by the General Electric Company. The device 90 controls the amount of current flowing in the D. C. winding 91 of a saturable reactor 92 having A. C. windings 93 and 94. Saturable reactor 92' is connected to the primary winding 87 of transformer 86 and controls the amount of power supplied thereto from a source of power designated by the numeral 95.

Controls

89, 90, and the saturable reactor 92 constitute a system of control which is well know in the art and which in itself forms no part of the invention.

In operation of the controls of Fig. 2, upon a rise in temperature affecting the thermocouple 88, a voltage signal is impressed on the control device 90 which causes the amount of current flowing in the D. C. saturatingwinding 9 1 to be decreased. This decreases the saturation of the saturable reactor 92 thereby increasing its impedance and decreasing the power supplied to the transformer 86'. The amount of heat supplied by the heating elements is thus reduced and the temperature reduced to the desired value. ture at the thermocouple 88 the operation is in the oposite direction and the amount of heat supplied is increased to bring the temperature back to the desired value.

By positioning the thermocouple 88 in the manner described where it is affected by heat from the ionizing means to the same extent that the charge in the charge bottle is, it is possible to maintain the temperature of the charge bottle with accuracy at the desired value. The thermocouple at the same time exercises control over both of the electrical heating elements which -are-connected in parallel, and the temperature in the vicinity of the ionizing means is thereby maintained. high enough to maintain the charge in that vicinity in a vaporized state. My invention provides an effective and eflicient way of maintaining the temperature ,of the charge being volatilized accurately at the desired value, and the position of the thermocouple 88 and associated control mechanism is such that removal and insertion of the charge bottle is not prevented or interfered with.

The embodiment of my invention which I have disclosed is representative of a preferred form and adaptation thereof. The invention is to be limited not by the disclosure but only in accordance with the scope of the claims appended hereto.

I claim:

1. In apparatus of the character described, in combination, containing means for a material to be vaporized,

heating means associated with said containing means for vaporizing'said material, said heating means including means situated adjacent a position normally occupied by vapor of said material, temperature responsive means controlling the heating means, said temperature responsive means being situated at an intermediate point as respects said containing means and said position so as to be affected by both the temperature in the region wherein vaporization is taking place and also the region normally occupied by vapor.

2. In apparatus of the character described, in combination, containing means for a material to be volatilized, heating means associated with said containing means for volatilizing said material, said heating means including means situated adjacent a position normally occupied by vapor of said material, means for ionizing said material in the vicinity of said position, temperature responsive means controlling the heating means, said temperature responsive means being situated at an inter mediate point as respects said containing means and said position so as to respond to both the temperature in the region wherein vaporization is taking place and the temperature in the vicinity of the ionizing means.

3. In apparatus of the character described, in combination, containing means for material to be vaporized, heating means associated with said containing means for vaporizing said material, means disposed at a position normally occupied by vapor for ionizing the vapor of said material, said ionizing means including electrical apparatus which generates an unsteady flow of heat during operation, temperature responsive means controlling the heating means, said temperature responsive means including an element situated at an intermediate point as respects said material and said position so that heat from said ionizing means substantially similarly affects said temperature responsive means and said material being volatilized so that the temperature responsive means may accurately control the temperature of the material being volatilized even though the how of heat from said ionizing means is unsteady.

4. An. apparatus of the character described, in com- Upon a fall in temperabination, containing means for material to. be volatilized, heating means associated with said containing means for volatili zing said material, means for ionizing vapor of said material, said ionizing means including electrical apparatus which generates an unsteady flow of heat during operation, said heating means including means for maintaining said material .in a vapor state in the vicinity of said ionizing means, temperature responsive means controlling said heating means, said temperature responsive means including an element situated at an intermediate point as respects the material being volatilized and the ionizing means so that heat from the ionizing means substantially similarly affects said element and said material being volatilized so that the temperature responsive means is able to accurately control the temperature of the material being volatilized even though the flow of heat from the ionizing means is unsteady.

5. In apparatus of the character described, in com-j bination, containing means for material to be vaporized, heating means for vaporizing said material associated with said containing means, said containing means including a vapor containing chamber and a passageway forming means for conveying vapor to said chamber, said heating means including means associated with said chamber having sufficient heating capacity to maintain a relatively higher temperature in said chamber so as to prevent condensation therein, and temperature responsive means for controlling said heating means, said temperature responsive means including an element responsive to the temperature at a point in the gradient between the material being vaporized and said chamber.

6. In apparatus of the character described, in combination, containing means for material to be vaporized, heating means for vaporizing said material associated with said containing means, said containing means including a vapor containing chamber and a passageway forming means for conveying vapor to said chamber, said heating means including means associated with said chamber having sufficient heating capacity to prevent condensation therein, means for ionizing material which has been maintained in a vaporized state in said chamber, and temperature responsive means for controlling said heating means, said temperature responsive means including an element responsive to temperature at a point in the region of said passageway forming means affected by heat from said heating means and said ionizing means.

7. In apparatus of the character described, in combination, containing means for material to be volatilized, heating means for volatilizing said material associated with said containing means, said containing means including a vapor containing chamber and a passageway forming means for conveying vapor to said chamber, means for ionizing vaporized material in said chamber, said ionizing means including an electrical apparatus which generates an unsteady flow of heat during operation, temperature responsive means for controlling the temperature of the heating means for volatilizing the material, said temperature responsive means including an element responsive to temperature at a point in the temperature gradient existing between said material being volatilized and said chamber, the position of said temperature responsive element being such that heat from said ionizing means substantially similarly affects said element and said material being volatilized so that the temperature responsive means is able to accurately control the temperature of the material being volatilized even though the flow of heat from said ionizing means is unsteady.

8. In apparatus of the character described, in combination, containing means for material to be vaporized, heating means associated with said containing means for vaporizing said material, said heating means including means situated in a position wherein it is desired to prevent condensation of vapor, means for ionizing said material in the vicinity of said position, means forming a vacuum chamber enclosing at least a part of said heating means and said ionizing means, means for evacuating the air from said chamber, temperature responsive means controlling the heating means, said temperature responsive means including an element situated at an intermediate point as respects said material and said ionizing means so as to be affected by both the temperature in the region wherein vaporization is taking place and the temperature in the vicinity of the ionizing means.

9. In apparatus of the character described, in combination, containing means for material to be volatilized, heating means for volatilizing said material associated with said containing means, said containing means including a vapor. containing chamber, ionizing means for ionizing vapor of said material, said ionizing means including electrical apparatus which generates an unsteady llow of heat during operation. said heating means comprising parallel connected electrically heating elements, one of said elements being arranged to generate heat for volatilizing said material and the other of said elements being arranged to supply heat for maintaining said material in a vapor state in the vicinity of said ionizing means, temperature responsve means for controlling said heating means, said temperature responsive means including an element situated at an intermediate point as respects said material and said ionizing means such that heat from said ionizing means substantially similarly afiects said element and said material being volatilized so that the temperature responsive means is able to accurately control the temperature of the material being volatilized even though the flow of heat from said ionizing means is unsteady.

10. In apparatus of the character described, in combination, containing means for material to be vaporized, heating means for vaporizing said material associated with said containing means, said containing means including a vapor containing chamber and a passageway forming means for conveying vapor to said chamber, said heating means including means associated with said chamber having sufiicient heating capacity to prevent condensation therein, means for ionizing material which has been maintained in a vaporized state in said chamber, means forming a vacuum tank inclosing said chamber, its associated heating means and said ionizing means, means for evacuating the air from said tank, and temperature responsive means for controlling said heating means, said temperature responsive means including an element responsive to the temperature of said passageway forming means.

11. In apparatus of the character described, in combination, containing means for material to be vaporized, said containing means having an outlet for vapor in its upper part, heating means associated with said containing means for vaporizing said material, means for ionizing said vapor adjacent said outlet and spaced from the said material to be vaporized, additional heating means adjacent to the ionizing means for preventing condensation of vapor in that vicinity, temperature responsive means controlling all of the heating means, and including a temperature responsive element located at a point intermediate the first heating means and the ionizing region so as to be responsive to heat from all of the heating means and from the ionizing means and to be exposed to heat from the ionizing means to sub- 3 stantially the same extent as the material to be vaporized is exposed thereto.

12. The structure of claim 11, wherein a converging passageway is provided to communicate vaporized ma terial to the ionizing means and the temperature responsive element is located at a point in said converging passageway.

References Cited in the file of this patent UNITED STATES PATENTS 2,149,729 Finch Mar. 7, 1939 2,189,618 Slepian Feb. 6, 1940 2,192,047 Miles Feb. 27, 1940 2,221,467 Bleakney Nov. 12, 1940

Claims

11. IN APPARATUS OF THE CHARACTER DESCRIBED IN COMBINATION, CONTAINING MEANS FOR MATERIAL TO BE VAPORIZED, SAID CONTAINING MEANS HAVING AN OUTLET FOR VAPOR IN ITS UPPER PART, HEATING MEANS ASSOCIATED WITH SAID CONTAINING MEANS FOR VAPORIZING SAID MATERIAL, MEANS FOR IONIZING SAID VAPOR ADJACENT SAID OUTLET AND SPACED FROM THE SAID MATERIAL TO BE VAPORIZED, ADDITIONAL HEATING MEANS ADJACENT TO THE IONIZING MEANS FOR PREVENTING CONDENSATION OF VAPOR IN THAT VICINITY, TEMPERATURE RESPONSIVE MEANS CONTROLLING ALL OF THE HEATING MEANS, AND INCLUDING A TEMPERATURE RESPONSIVE ELEMENT LOCATED AT A POINT INTERMEDIATE THE FIRST HEATING MEANS AND THE IONIZING REGION SO AS TO BE RESPONSIVE TO HEAT FROM ALL OF THE HEATING MEANS AND FROM THE IONIZING MEANS AND TO BE EXPOSED TO HEAT FROM THE IONIZING MEANS TO SUBSTANTIALLY THE SAME EXTENT AS THE MATERIAL TO BE VAPORIZED IS EXPOSED THERTO.