US2882411A

US2882411A - Ion producing mechanism

Info

Publication number: US2882411A
Application number: US679883A
Authority: US
Inventors: Frank F Oppenheimer
Original assignee: Individual
Current assignee: Individual
Priority date: 1946-06-28
Filing date: 1946-06-28
Publication date: 1959-04-14
Anticipated expiration: 1976-04-14

Description

April 14, 1959 I F. F. CPPENHEIMER ,4

ION PRODUCING MECHANISM Filed June 28, 1946 2 Sheets-Sheet 1 ATTORNEY April .1959 F. Fl OPPENHEIMER 2,882,411

ION PRODUCING MECHANISM Filed June 28, 1946 2 Sheets-Sheet 2 i. 1 a 48 f INVENTOR. fkAA/K OPPf/W/f/Mfk A YTOHNEY United States Patent ION PRODUCING MECHANISM Application June 28, 1946, Serial No. 679,883 6 Claims. (Cl. 250-419) This invention relates to calutrons and more particularly to means for introducing gas at selected points in the arc chamber of a calutron ion source.

Calutrons are described in general in Atomic Energy for Military Purposes by H. D. Smyth and in greater detail in US. Patent No. 2,709,222, to Ernest 0. Lawrence, which issued on May 24, 1955. Calutrons have in separating the isotopes of uranium for military energy purposes. In general, ions of a polyisotopic mixture of a desired element are formed and projected into a magnetic field. Thereafter, the ions travel in curved paths, the ions of greater mass describing flatter curves than the ions of lesser mass. Suitable collectors are placed along each path, preferably at the 180 point in each curve. The ions are there neutralized and collected substantially separated from ions of different mass.

The ions are formed in an arc discharge that takes place in a vapor containing the desired element, for example, uranium tetrachloride has been used for producing uranium ions. This are discharge takes place in a confined region designated as an arc chamber. time to time it has been found that the arc is unsteady, particularly in the anode region of the arc discharge. I have discovered that this unsteadiness in the arc may 'be remedied to a certain extent by introducing all of or part of the charge gas at the region of the anode. The resulting arc is much steadier, resulting in an ion beam of increased current.

It is therefore an object of the present invention to provide a calutron are that is fairly reliable and steady.

Another object of the invention is to provide means for directing all of or part of a charge vapor toward the anode of a calutron arc discharge.

Othere objects and advantages of-the invention will be apparent in the following description and claims considered together with the accompanying drawings, in which: I

looking along the magnetic tank and ion source secured Figure l isa plan view field of 'a'calutron vacuum to the vacuum tank;

Fig. 2 is an enlarged sectional view of the arc block portion of Fig. 1, taken along the line 2-2 of Fig. 1;

Fig. 3 is an isometric view of the anode region of the arc block of Fig. 2; and

Fig. 4 is a modified form of the invention wherein the entire charge gas is introduced at the anode.

Fig. 5 is a partial cross sectional view of a modified form of the invention wherein the charge gas is introduced at the base of the arc chamber.

Referring to Fig. 1, a generally tubular vacuum tank has a branch connection 11 leading to suitable vacuum pumps for reducing the pressure within the tank to a desired level, such as 10" or 1O mm. Hg. Secured to an outer face plate 12 of the vacuum tank 10 is a metal tube 13 supporting adjusting mechanism 14 for a stem assembly 15 projecting therefrom and back through the tube 13 and having an arc block assembly 16 supported From on its inner end. A liner 17 is mounted within the vacuum tank 10 on insulators 18 and a suitable negative electric potential is maintained thereon to attract positive ions from the arc block 16. A magnetic field 19 (Fig. 2) permeates the entire structure. Two plates 21 are attached to the liner 17 opposite the arc block 16 and define an elongated slit 22.

In the general operation of the calutron, positive ions are generated in the are block 16 and because of the negative potential on the liner 17 are attracted thereto and pass through the slit 22, thereafter describing gen? erally circular paths through the magnetic field. Suitable collectors (not shown) are utilized, as previously mentioned.

Referring to Figs. 1 and 2, the arc block 16 is sup portedon the end of a tubular stem 23 of the stem assembly 15 by means of a spider-like bracket 24 designed 29 is an arc housing 31 to reduce the conduction of heat to a minimum from the arc block 16 to the stern assembly 15. Secured to the spider 24 is a reservoir housing 25 having a reservoir chamber 26 formed therein and heated by two e1ec been principally employed and very successfully employed tric resistance heaters 27. A nipple 28 secured to the left side (Fig. 2) of the reservoir housing 25 communicates the chamber 26 with a distributing chamber 29. Secured on the outer end of the distributing chamber communicating with the distributing chamber 29 by an upper aperture 32 and a lower aperture 33. The are housing 31 defines an arc chamber 34 having a restricted outlet formed by two arc slit plates 36.

Electrons are obtained for the arc discharge from a filament 37 heated to emissivity by a conductive curhundred volts negative 'with rent supplied by two water-cooled leads 38. The filament 37 is insulated from the reservoir, distributing chamber, and are housing 31 and maintained at several respect thereto. The collimating effect of the magnetic field causes the electrons emitted from the filament 37 to describe a narrow ribbon of emission down along the length of the arc chamber 34. An anode 39 is provided for intercepting these electrons and although the anode 39 may be maintained at any desired potential, I prefer to maintain it at the same potential as the arc housing 31.

The detailed structure of the vapor flow in accordance with the invention is shown in Figs. 2 and 3. An L-shaped baflie 41 is secured adjacent to the lower vapor aperture 33 to direct the flow of vapor at the anode 39.

In operation, a charge bottle of any desired type is inserted in the reservoir chamber 26 and contains a material that may "be vaporized by the application of heat. Heat is supplied by the heaters 27 generating vapor which fills the reservior chamber 26 and flows through the nipple 28 into the distributing chamber 29. The vapor then flows out through the upper aperture 32 and the lower baffied aperture 33 into the arc chamber 34. The vapor is here bombarded by electrons from the filament 37 that travel along the magnetic field until they strike the anode 39. Positive ions are formed in this are discharge and are withdrawn for utilization, as previously mentioned. The presence of the bafiie 41 directing a substantial part of the flow at the anode 39 greatly increases the stability of the arc, resulting in a more prodigious and steady formation of ions.

Referring to Fig. 4, there is shown a modification of my invention wherein the entire gas fiow is directed at the anode. An arc block 45 is formed of a single piece of metal, such as copper, and is maintained at a potential positive with respect to an emissive filament 46. The block 45 contains two interconnected reservoir bores 47 and an, arc chamber bore 48. The output vapor from the bores '47 is directed into a bore. 49 to which is con.- necteda tubular member 51 directing the vapor flow to the bottom of the arc chamber bore 48. The tube 51 .has an outlet aperture 52 that directs the gas flowupwardly towardthe filament 46. Further, the filament 46 is so positioned with respect to the magnetic field and the outlet 52 that the electrons emittedtherefrom actually enter the outlet 52 of the tube 51.

inseam In operation of the modification of Fig. 4, an appropnate charge material is placed in the reservoir bores 47 and heated by heaters (not shown) causing vapor to be formed that travels through the tube 51 and thence upwardly through the outlet 52. Electronsv bombard. the resulting vapor that .fills the arc bore 48 and also enter the outlet aperture 52 in the tube 51. An .arc discharge thereby set up generating ions which are withdrawn and utilized in a manner previously described. The intrcduction of the .entire gas charge at the anode eliminates unsteadiness of the are at the anode region.

. Referring to Fig. there .is shown a modification O my invention wherein the entire gas flowis directed onto the. anode. In this modification an arc block 450 is formed of a single piece of metal, such as copper, and is maintained at a positive potential with respect to emissive filament 46 as described heretofore. Block 45a contains two interconnecting reservoir bores 47 and an arc chamber 48. The output vapor from the bores 47 is directed downward and into slot 53 in base plate 54 which is removably attached to block 45a. The charge vapor flows through slot 53 into arc chamber 48 and thereby enters arc chamber 48 at the bottom and flows upwardly in arc chamber 48 toward filament 46. Further, the filament 46 is sopositioned with respect to the magnetic field and the base plate 54 and slot 53 that the electrons emitted from filament 46 actually enter and impinge upon the outlet end of slot 53.

In operation of the modification of Fig. 5 an appropriate charge material is placed in block 45a and heated by heaters (not shown) causing vapor to be formed which travels through slot 53 cut in base plate 54 and thence into arc chamber 48 entering at the base of arc chamber 48. Electrons emitted from filament 46 bombard the resulting vapor that fills arc chamber 48 and also enter the exit end of slot 53 in base plate 54. An arc discharge directed by the magneticfield as described is thereby set up generating ions which are withdrawn and utilized in a manner previously discussed. the anode eliminates the unsteadiness of the arc in the anode region.

Although I have described my invention with respect to a particular embodiment thereof, it is not limited "to this embodiment nor otherwise except by the terms of the following claims.

What is claimed is:

1. In an apparatus for developing gaseous ions from a vaporizable source compound, the combination of means The introduction of the entire gas charge at in the reservoir bores 47 for establishing an, ar dis harg said means comprising an elongated arc chamber including means constituting an anode for said are discharge and an electron emissive cathode spaced from said chamber at one end thereof, means for introducing a vapor of said compound into said chamber, and bafile means Positioned in the path of vapor flow for directing the vapors entering said chamber to an end thereof opposite said cathode.

2. An apparatus for developing gaseous ions from a vaporizable source compound comprising means defining an elongated region for gas ionization, means forintroducing into said region a vapor of said compound, an anode and a cathode for establishing an arc discharge through said region in the direction of its elongation to provide a discharge path containing positive ions of said vapor throughout said region, means disposed between said anode and cathode for directing the flow of an additional supply of said vapor directly onto. the anode of said discharge path.

3. A calutron comprising means forming a gas ionization chamber of elongated form, an electron emitter disposed adjacent one, end of said chamber, a tubular anode disposed adjacent the other end of the chamber and'havv ing an opening directed toward the electron emitter, and means for supplying to the tube a gas to be ionized.

4. A calutron comprising a block having open-ended parallel arc and charge cavities, a channeled plate attached to the block and covering one end of the cavities and communicating the charge and are cavities, and an electron emitter disposed adjacent, the other end'of the arc cavity.

5. Acalutron comprising an ion source includingan elongated arc chamber, an electron emitting filamentarranged at one end of said chamber, an electron receiving anode arranged at the other end of said chamber, means for admitting gas to be ionized to said chamber, andia baffle for directing part of said gas to flow across said anode.

6. In an ion source for a calutron, the combination comprising an arc block having an elongated ionization chamber with an exit slit extending substantially the length thereof, an electron emitting filament arranged at one end of said chamber, an electron receiving anode arranged at the other end of said chamber, means for admitting a gas to be ionized to said chambenand means disposed between said anode and filament for directing a portion of said gas directly onto said anode.

References Cited in the file of this patent UNITED STATES PATENTS 2,374,205 Hoskins Apr.'24, 1945 OTHER REFERENC S 'Tuve et al.: Physical Review, Aug. 1, 1935, vol. 48, pp. 241-243.

Timoshenko: Review of Scientific 'Instrument tn 1938,vol. 9,pP. 187 and 188.