US2882410A

US2882410A - Ion source

Info

Publication number: US2882410A
Application number: US676608A
Authority: US
Inventors: William M Brobeck
Original assignee: Individual
Current assignee: Individual
Priority date: 1946-06-14
Filing date: 1946-06-14
Publication date: 1959-04-14
Anticipated expiration: 1976-04-14

Description

April 14, 19,59

w. M. BRoBEcK ION= SOURCE Filed June 14, 1946 A 3 Sheets-Sheet 1 INVENTOR. WML/,4M M ofcx- ATTORNEY.

April 14, 1959 BRoBEcK ION SOURCE Filed June 14. 1946 3 Sheets-Sheet 2 lllllm'..

' INVENTOR. W/L MM M oEcK ATTORNEY.

W. M. BROBECK ION SOURCE April 14, 1959 5 Sheets-Sheet 3 INVENTOR WML/,4M M ofck Filed June 14', 1946 ATTORNEY.

United States' Parf f' ION SOURCE William M. Brobeck, Berkeley, Calif., assignor to the United States of America as represented by the United States'Atomic Energy Commission Application June 14, 1946, Serial No. 676,608 4c1aims. (ci. 25o-41.9)

This invention relates to calutrons and more particularly to an arrangement therein whereby charge bottles in a calutron source unit may be replaced without admitting atmospheric air to the calutron vacuum chamber.

Calutrons are described in general in Atomic Energy for Military Purposes by H. D. Smyth, and are described in great detail in U.S. Patent No. 2,709,222, issued to Ernest O. Lawrence on May 24, 1955. Calutrons are commercial isotope separators, separating large quantities of material compared to laboratory instruments which separate only microscopic amounts of material. They have been principally used, and very successfully used, in separating the isotopes of uranium, the isotope U235 being separated from the isotope H238. In general, thel material to be separated in a calutron is placed in an ion source unit, and therein converted to ionic form, whereupon it is projected by electrical means into a magnetic field. Thereafter the ions travel in curved paths due to the magnetic forces, the heavier ions travel'- ing in paths of greater radius than lighter ions. lon collectors are placed across these paths at some convenient point, such as the 180 point of travel of the ions along their curved paths. The entire apparatus is evacuated so as to reduce the number of collisions that the ions encounter in traveling through the magnetic ield to the collector.

The substance to be separated is usually vaporized and the vapor bombarded by an electron stream to ionize the particles. In the separation of uranium isotopes, uranium tetrachloride and' uranium hexachloride have beenv used, which substances are solids at room temperature. The charge material is placed in a heater or furnace region whereupon a vapor is produced which is directed into an arc chamber, and an arc discharge takes place due. to the electron bombardment of the Vapor. Ions are formed in this discharge and removed from the arc. chamber by a strong electric field, and projected into the magnetic field as just described. The charge substance is' usually placed in separate containers and the container inserted in the calutron prior to operation. lnasmuch as heat transmission limitations and production techniques limit the size of this bottle, the charge is frequently consumed even though the calutron unit as a whole is still able to operate. The present invention, therefore, provides means for permitting the removal of an empty charge bottle and the insertion of a fresh charge bottle without letting the entire apparatus down to air. This feature isimportant when it is realized that. pumping out time may consume from 12 to 24 hours for a calutron. and the removal of parts otherwise necessary to add a new charge bottle involves considerable labor.

It is therefore an object of the invention to provide mcansjforreplacing the charge container of the calutron without letting the calutron tank go down to atmospheric pressure.

Another object of the invention is to provide vacuum lock apparatus for a calutron which permits the removal 2,882,410 vPatented Apr. 1.4,. 1.959

and replacement of chargebottles without. lettinglnthe calutron down to. atmospheric pressure. ,v

Other objects and advantages ofthe invention will be. apparent in the followingy description. and .claims considered together with the accompanying. drawings forming,` a part thereof, in. which:

Fig. 1 is a plan view partly in section of a calutron. ion source unit,

Fig. 2 is a plan view of the arc chamber portion of the calutron source of Fig.. 1 wherein that portion isin. section,

Fig. 3 is a fragmentary elevational. view taken along. the line 3-3 ofFig. l,

. Fig. 4 is an elevation view in full. section of. the entireL calutron ion source showing a charge bottle in the vac uum lock, preparatory to insertion for operation, the section being taken along the line 4-4 of Fig. l,

Fig. 5 is a sectional elevation. view similar to Fig.V 4 but showing the charge bottle in its operative position,

' Fig. 6 is an elevation view of the valve operating; mechanism of the vacuum lock, and` Fig. 7 isv an elevation view in section of the valvey mechanism takenv along. the line 7-7 of Fig. l.

Referring to Fig. 1, there is shown a face plate. 111 forming a. part of the vacuum .envelope in which the calutron portions operate, and. secured thereto are two metal sheets 12, which support. an are block 13 on the inner end, that is. the side of the. face plate 11 that is subjected to vacuum. Secured to the arc block 13 is. a. heater block 14 and a. reservoir housing 16 is attached: to the heater block. ln normal operation a charge bottle or container is placed. in the housing 16 and. its contents vaporized by heat. from. a heater 17 castintegrally with` the housing 16. The vapor passes through an angular conduit 18 into an elongated vapor distributing chamber 19. From there it flows through drilled passages 21 into the

arc chambers

22 and 23. The vapor then passes: through semicircular baffles 24 disposed in the arc chambers and thereafter is subjected to bombardment by an electron stream in each arcchamber, whereupon an arc discharge is formed. Arc slit plates 26 form a restricted! outlet 27 for each arc chamber. The ions formed in vthe arc discharge are withdrawn from the

arc chambers

22 and 23 through the slits 27 by an electric eld set -up between the arc block 13 and an electrode structure 28 having two slits 29 through which the ions pass. The: accelerating structure 28 is insulated from the entire. vacuum tank, including the face plate 11, byinsulators (not shown) and a suitable negativepotential is applied. thereto, such as 30 kv.

Referring now to Figs. 2, 3, and 4 there is shown the. filament structure giving rise to the electron stream of the arc. A supporting stem 31 contains three leads 32,.. 33 and 34, which are insulated from each other and from the stem 31. These leads terminate. in

clamp blocks

32a, 33a and 34a respectively which clamp two

filaments

36 and 37. The two outer leads 32 and 34 are at the same potential and several. volts above the middle lead 33, so that current ilows from the two outer leads through the

filaments

36 and 37 into the center lead 33. The con,- ductive current heats the filaments to emissivity. The three leads 32,. 33 and 34 are several; hundred volts negative with reference to theI arc block 13, and electrons emitted from the filaments are attracted towardthe arc block 13. The strong magnetic field, however, permeates the Whole structure collimating the electronsl so that they vacuum lock structure andthe retracting mechanism for charge bottles, allin accordance with the invention.'

the' Secured to the outerv or atmospheric side of the face plate 11 is an angular plate 41 to which is secured a Second angular plate 42 to which is soldered, or otherwise secured, a tubular member 43, forming the principal part of the vacuum lock. A ange 44 on the outer end of the tube 43 forms a securing plate for a reduced tube 45, also having an outer ange 46. Secured to this outer ange 46 is a vacuum seal bushing assembly 47 having a. slidable rod 48 passing therethrough. This entire mechansm acts as a vacuum lock f or a charge bottle 49 which is transported therethrough to thereservoir 16. This transportation isperformed by a slidable carriage assemblyincluding a tube 51 secured by flanges to the slidable rod 48. A tubular guide 52is secured to the inner side of the face plate 11 to aid in the movement of the charge bottle into the reservoir 16. A vacuum line 53 is connected to the tubular air lock member 43 and evacuates this chamber to the same pressure as that prevailing inside the face plate 11.

Fig. shows the charge container or bottle 49 in its operating condition, a frangible seal 54 being broken by a fixed spike 56. The partition 57 in the charge bottle prevents the sliding of the material into the vapor conduit in the event that the entire seal 54 is broken. When is desired to remove the charge bottle for any reason, such as consumption of thematerial, the rod 48 is manually pulled and since the charge bottle 49 is held by a carriage in the inner endfthereof, the lentire charge bottle is removedfrom the reservoir 16 into the tubular support 45 as shown in Fig. 4. vWhen this operation is completedua vacuum-valve 58'is manually closed, shutting olf the vacuum lock from `communication lwith the interior of the calutron unit which is on the right hand side of the face plate 11. When this is completed, a vacuum line 53 is closed by a valve 55 and the seal assembly 47 is removed from the flange 46. The charge bottle 49 is then completely freed from any mechanical connection with the entire source structure, permitting the charge bottle to be replaced Yby a fresh one. When it is desired to replace the charge bottle in the source structure the seal assembly 47 is ysecured to the Ilange 46 as shown in Fig. 4. The vacuum control valve 55 is then opened and after a suitable lapse of time the pressure is reduced inside the tubular member 43 to a pressure approximating that used in the main calutron tank. Valve 58 is then manually opened as shown in Fig. 5 and the rod 48 manually pushed until the charge bottle 49 assumes the position as shown in Fig. 5, the frangible seal 54 breaking upon the last part of the movement when it contacts the iixed spike 56.

The operating mechanism for the ap valve 58 is shown in Figs. 6 and 7. The valve 58 is pin-jointed to a lever arm 59 soldered to a shaft 61, which passes through a vacuum seal 62 and has a short lever 63 secured on its outer end. The lever 63 is connected by a link 64 to the short end of a pivoted L-shaped handle 66. The entire valve operating mechanism is shown iny s'olid outline in Fig. 6 when the valve is in closed position, and in dotted outline for the open position of the valve S8. The pin-jointing of the valve 58 to thelever 59 permits a limited pivoted movement with respect to the lever so that the valve is free to strike the valve seat area squarely.

The operation of the entire apparatus canbest be described with reference to all of the gures. The charge bottle 49 is in the position lshown in Fig. 5 and heat is stream, thereby increasapplied by the heater 17, vaporizing the contents thereof, which in the case of uranium charge material may be uranium tetrachloride or uranium hexachloride. The vapor passes through the distributing chamber 19 and the passages 21 through the bales 24 to the arc chambers where it is bombarded by electrons emanating from the

filaments

36 and 37 and thereafter passes through the delining holes 38. The ions generated in the arc discharge are accelerated through the accelerating slits 29 by virtue of a negative potential applied to the entire accelerating structure 28. In due course the contents of the charge bottle 49 are consumed, and the charge bottle is removed by manually pulling on the rod 48 until the charge bottle is in the position shown in Fig. 4. Thereupon the flap valve 58 is manually closed and seal assembly 47 disconnected from the flange 46, allowing the charge bottle to be free of the source structure. A fresh chargebottle is inserted in the carriage mechanism 51 on the end of the rod 48, the seal assembly 47 reconnected and theair within the vacum lock member 43 evacuated by means of the vacuum line 53. When a suitable pressure is reached, the ap valve S8 is opened and the charge bottle slid into position as indicated in Fig. 5.

Although the invention has been described with reference to a particular embodiment thereof, itis not limited to this embodiment or otherwise except by the terms of the following claims.

What is claimed is:

1 A calutron comprising a vacuum envelope, an ion source structure disposed therein and including a reservoir having an opening toward one wall of the vacuum envelope, a charge bottle adapted tobe placed in the'l reservoir for furnishing a charge gas 'to the ion source? unit, and means secured to the outside of the wall of the' vacuum tank for withdrawing the charge bottle and replacing it in the reservoir without reducing the pressure in the vacuum tank.

2. A calutron comprising a vacuum tank, an ion source` unit disposed therein having a reservoir open toward a wall of the vacuum tank, a charge bottle adapted to be placed in the reservoir, a vacuum lock secured to the outside of the tank wall and communicating with the interior of the tank, a valve for closing the vacuum lock `from communication with the interior of the vacuum tank, means for evacuating the vacuum lock, and means for removing a wall of the vacuum lock for removal .of the charge bottle after it is withdrawn into the vacuum lock.

reservoir and adapted to be broken by the spike when it is placed in operating position, and means for withdrawing the charge bottle and replacing it without admitting the gas to the vacuum tank, whereby a sealed charge bottle may be inserted in a calutron source unit and may` be automatically opened by the insertion operation.

4. A'calutron comprising an arc block, into which a gas is adapted to flow, a baie disposed in the arm block anterior tothe electron stream, a distributing chamber member secured to the arcblock in communication'` therewith through holes formed in the arc block, and a source of charge gas connected to the distributing member, whereby the gas fed to the arc is distributed irst-iu the distributing chamber and second in the the bales and the distributing chamber.

References Cited in the file of this patent UNITED STATES PATENTS 2,264,209 Krause Nov. 25,1941' space between