US2531065A

US2531065A - Apparatus for changing the ion source of a cyclotron

Info

Publication number: US2531065A
Application number: US158512A
Authority: US
Inventors: John J Livingood; John V Peters; Royal A Streeter
Original assignee: Collins Radio Co
Current assignee: Collins Radio Co
Priority date: 1950-04-27
Filing date: 1950-04-27
Publication date: 1950-11-21
Anticipated expiration: 1967-11-21

Description

Nov. 21, 1950 J. J. LIVINGOOD EIAL 2,531,055

APPARATUS FOR CHANGING THE ION SOURCE OF A CYCLOTRON Filed mm 27, 1950 .4 Sheets-Shea} 1 IN VEN TORS dahw J. l/w/vaooo /P0 YAL A.5TREE TEIP N JOHN V. PETERS BY W:

ATTORNEY Nov. 21, 1950 APPARATUS FOR CHANGING THE ION SOURCE OF A CYCLOTRON- Filed Abril 27, 1950 4 Sheets-Sheet 2 INVENTORS JoH/v J. l wuysaoa Pow AL A. 57/955721? JOHN V. PETERS Arr RNEY J. J. LIVINGOOD ETAL- 2,531,063-- Nov. 21, 1950 J. J. LIVINGOOD EIAL 2,531,065

APPARATUS FOR CHANGING SOURCEOF A CYCLOTRON Filed April 27, 1950 4 Sheets-Sheet 3 r: INVENTORS JaH/v J. Z lV/IV600D A Row. A. STREETER 4 JOHA/MPETERS I- 5 BY 77%; m1;

ATTORNEY Nov. 21,1950 J. J. LIYINGOQD arm, 2,531,055

APPARATUS Fox. CHANGING m ION SOURCE OF A CYCLOTRON Filed An ril 2*], 1950 4 Sheets-Sheet 4 INVENTORS JoH/v J L/wlveobo R0 YAL A. .STREETER JOHN V PETERS v BY 5 M Arro NEY Patented Nov. 21, 1950 UNITED STATES PATENT "OFFICE APPARATUS FOR CHANGING THE ION SOURCE OF A CYGLQTRQN poration of Iowa Application April 27, 1950, SerialNo. 158,512

16 Claims. 1

This invention relates in general to cyclotrons; and in particular to apparatus for automatically removingthe cathode and anode of an ion gun from a cyclotron without the necessity of a person being present in the room.

With the development of the field of nuclearphysics there has arisen the need for man-made machines which will induce radioactivity in normally inert materials. A study of the resultant radioactivity gives a hint to the structure of'the activated atom. One of'the machines built for inducing radioactivity is the cyclotron. When the cyclotron is operated, the region in its vicinity is subjected to very concentrated radiation. Even after the machine is turned off, a large amount of residual radiation exists. "it is well known that the human body can be safely exposed to a particular intensity of radiation'ior just so long. In some of the large cyclotronsnow in operation this time is three minutes per day, even when the machine is turned 01f. In other words, when the cyclotron is operating and is momentarily shut down for adjustment, the person making the adjustment should not remain in the cyclotron room more than a few minutes. The operation 1 the cyclotron is usually controlled from an adjoining room which is shielded by lead or othersuitable material from the harm ul radiation. One of the requirements for the operation of a cyclotron is that there must be an ion source, and the ype of ion source used has a hot filament, generally of tungsten, over which a suitable gas moves and the electron emission of the high negative filament results in the formation of, ions.

These ions are the bullets of the cyclotron. At the extremely high temperatures which the tungsten filament must be operated, it is frequently necessary to replace the filament. Previously an operator has entered the room and hurriedly removed the filament and replaced it. The dee chamber of the cyclotron must be maintained at a very low pressure, and before the filament may be removed it must be pulled through a pressure lock which prevents the atmospheric pressure from spoiling the vacuum in the chamber. This takes time, and the operator is being needlessly exposed'to harmful radiation.

It is an object of this invention, therefore, to provide apparatus for automatically removing the ion source of a, cyclotron without the necessity of an operator being present in the cyclotron room.

Another object of this invention is to provide means for automatically withdrawing the cathode of a cyclotron from the dee chamber without losing the vacuum in the cyclotron.

"Yet another object of this invention is to provide means for automatically changing the cathode which has been removed from the cyclotron and re-positioning the new one in the dee chamber.

Still another object of this invention is to prov'ide means for automatically removing and re-' placing the anode of a cyclotron.

A Aieature of this invention is .found in the provision for a track which carries a first carriage to which the cathode is connected, and a second carriage to which the anode is connected. Means are provided for automatically moving the carriages longitudinally of the cyclotron through suitable pressure chambers. The replacement cathodes and anodes are mounted on a movable cart which can remove the old parts and replace them.

Further objects, features, and advantages of this invention will become apparent from the following description and claims when read in vie of the. drawings, in. which:

Figure l is a top sectional View illustrating a cyclotron, and an operator in an adjoining room manipulating controls for automatically removing the ion source;

Figure .2 is a side view of the ion source removing apparatus;

Figure 3 is a sectional view taken on line AA of Figure 4, and illustrates the removal and replacement mechanism for the ion source;

Figure 4 is a rear view of the carriage for 'removing the ion source members;

Figure '5 is a detailed'view of'supporting means for holding the free end of the cathode and anode as they are withdrawn from the dee chamber,

Figure .6 is a detailed View of the anode door; and,

Figure 7 is an end view of the cathode carriage.

Figure v1 illustrates a cyclotron comprising the does It], and II which are surrounded by the dee chamber wall [2. An ion source l3 extends into the dee chamber formed by the wall l2 and terminates between the does. It is to be understood; of course, that the head It extends up between the dees whereas the longitudinal portion ofthe ion source l'3'is below the plane of the dees so that, it does not interfere with the path" of the accelerated particles. The ions emerge from, the head i l of the ion source and are actuated by the alternating potential applied be.- tweenthe docs ll)v and H and by the direct current magnetic field applied at right angles to the dees. The means for producing the magnetic field are not shown because they are well known to those skilled in the art. The charged particles travel in a spiralling path with ever increasing velocity until they emerge from the dees and impinge on the target It. The target is activated by the bombardment and the characteristics of the bombarded material are studied.

It is to be understood, of course, that the dee chamber is maintained at a very low pressure. This is to prevent the charged particles from having too large a number of collisions with residual molecules.

Figure 2 illustrates in more detail the ion source I3. It comprises a tube ll which carries at its end the filament I3. It is desired to maintain the filament til at a thermal emission temperature, and therefore, a suitable heating potential is maintained between the ends I9 and 20 of filament IS. The leads supplying the heating potential pass through the tube I! and terminate in the filament ends I9 and 29, respectively. An upright supporting means 2| supports the cathode structure when it is removed from the dee chamber. A carriage 22 carries an upright plate 39 which is connected to the end 23 of the tube I1. The carriage 22 rides on a pair of rails 24 and is thus movable longitudinally of the cyclotron.

The cathode filament I8 and the tube Il' are received within the anode tube 26 during operation. The anode tube 26 has an internal diameter large enough to receive the tube H. A head 27 extends upwardly from the end of tube 26 and is formed with a slot 23, for allowing the ions to emerge. The tubes I1 and 26 have a clearance between them large enough to allow gas to pass therebetween. The gas travels through the space between the outer wall of tube I! and the inner wall of the tube 26 and passes the filament I8, where electron emission from the hot cathode flowing to the anode head 21 changes a certain portion of the gas molecules to ions. The tube 29 is maintained at a positive potential with respect to the filament l8. The charged particles emerge from the slot 29 into the dee chamber where they are accelerated.

When it is desired to remove the cathode, perhaps because the filament I8 has burned out, the tube Il' may be pulled longitudinally out of the tube 29 until the filament I3 is within the space formed by a plate 29 and a cylindrical member 3| attached to the plate 32.

The tube I"! has a plate 33 slidably mounted theron. The plate 33 holds a gasket, not shown which forms an airtight seal between the plate and the tube. An opening 34 formed in plate 29 has a clamping member 35 which is detachably connectible to the plate 33. If the carriage 22 is moved longitudinally of the support member 36, the tube will slide past the plate 33 and the rubber gasket will prevent an air leak. When the filament is within the confines of the space formed by the

plates

29 and 32 and cylindrical member 3|, a door 31, which is pivotally supported by the pin 38, may be moved to a position which seals the end of tube 26. The door 31 may be controlled by air pressure in a manner well known to those skilled in the art. After the door 31 is closed, air is admitted to the chamber about the cathode |8 through a tube I in order to equalize the internal and external pressure. The clamping member 35 is then released by air pressure and the cathode may be withdrawn completely. The plate 33 is removed with the cathode.

A driving means which may be an electric motor, for example, is designated generally as 43 and drives a belt 44 which passes over the pulleys 45, 46 and 41. The belt 44 travels between the tracks 24 and carries thereon a bracket 49. The bracket 49 may be moved longitudinally back and forth along the support 36 by the motor 43. The bracket 49 has a slot 5| formed therein for receiving a pivoted hook 52 carried on the carriage 22. The hook 52 is engageable with the bracket in the slot 5| and as the belt 44 is moved clockwise with respect to Figure 2, the cathode will be withdrawn from the tube 26, providing that the holding means 42 are released simultaneously. When the bracket 49 passes over the support 2|, the catch of the support is released to allow it to pivot upwardly so that its roller 53 may engage the tube ll of the cathode. The bracket 49 continues to move rearwardly, withdrawing the cathode from the anode tube. When the filament I8 is within the chamber formed between the

plates

29 and 32, the door 31 is actuated and then the bracket 49 is moved further rearwardly to completely remove the cathode from the confines of the anode. Once the oathode is completely removed it may be lifted bodily upwardly and off the tracks 24 and replaced by a new one. If only the cathode is to be changed the motion of the belt 44 is reversed and the bracket 49 pushes the new cathode until the filament I8 has passed into the chamber between the

plate

29 and 32. The clamp 35 engages plate 33 and forms an airtight seal. The pressure is reduced through the tube I5. During operation of the cyclotron the gas to be accelerated is admitted through tube I5. The door 31 is then opened and carriage 22 moved until the holding means 42 grasp the holding means 4| completing the operation.

The bracket 49 engages the carriage 22 to push it into the operating position. The hook 52 over-rides the bracket 49 until it engages the carriage 22. The support 2| remains upright supporting the tube ll of the cathode until the carriage 22 releases a catch, shown in Figure 5, that allows the support 2| to pivot downwardly as the carriage 22 passes over.

Figure 5 illustrates the support 2| in detail. It comprises the lever 94 which is pivotally supported by the pins 96 on the bracket 91 connected to support member 36. A second lever 98 is pivotally connected to the bracket 91 by the pin 99 and its opposite end is pivotally connected to a short link IOI which has its opposite end pivotally fastened to the lever 91% intermediate its ends. A trigger portion I02 extends from the link IBI for releasing the brace formed by lever 93 and link IilI. A stop I93 engages the pivot joint between lever 98 and link It. A spring I64 connected about the pivot 96 urges the lever 94 to the up position shown in Figure 5.

The carriage 22 has a trigger engaging portion, not shown, which engages the trigger I02 to allow the lever 94 to be urged downwardly as the carriage passes over it. The belt 44, as best shown in Figure 1, comprises the two chains I 06 and I0! attached to either side of the bracket 49.

Behind the bracket 49 connected between chains I03 and ID! are a plurality of transverse members I08. These members hold the support member 2| in its down position after the carriage 22 has passed thereover, thus preventing it from whine up behind the carriage to jam-the ap paratusi It; is desirable at timesto remove the anode." The anode tube '2t=- terminates in the plate I3 2; whichis in turn-m'ounted' on a carriageifitwhich rides :on a pairof: tracks 55 which-are outside the tracks 24'. The plate 29 and cylindrical member 3l'are also mountedon the carriage i l" arid m'ove asa unit. therewith. Theplate-3-2 is clamped to a plate Why the clamping means li'lr The plate 56 has formed therein an opening 58 largeenough'to allow the-head 27 of -th'e' anodetobe removed. A-generally corrugated c'ylin drical member 59:connects the plate 5'5-with'a' plate 6| which is also forn'iedwithan opening for allowing the head 21 ofthe'an'odeato bere mdvedl The plate'fil is joined by the cylindrical member 62 to aplate fifiattached to =thecyclotron= chamber wall l2. A doorlit'is'pivotally sup ported by a pin Min-the space between theplates To remove theanode; the cathode must nrstbe removed. and taken on: the track 2 4'. After thishas been done, the-belt 45 1s drivencounter clockwise until the bracket' ill engagesa hook El connected to the carriage 5 3; The belt Bi and: 662

is-then drive'nclockwise by the driving-means 43 thus pulling the carriage 54 along: the tracks 55 until the anode head This within th'e spa'ce between the plates 5%" and 6|. Itis to-beunderstoodpof course, that the clamping means Ei'i must" bereleased before the carriage 54 may be withdrawm When the head 21' isRwithin the confines of-=the member-.59',-the door ii i's swung to a closed position to maintain the vacuum" Sil formeddrr-the bracket" I09. Thus the bracket I may be rotated slightly-relative to the plate 56. Levers 89 aremounte'd'onthepins 8 2'; and links; 91 are pivotally connectedat either endto thebracket Hill and the ends-of thelev'ers 89; If the bracket j'Elfl is-rotatedrelative--tothe plate 56, the levers 89 engage and disengage, respectively the door 68, Thus the door may beconnected or disconnected to the plate 68 A 'rubber' gasket SZYI-ltsin a slot formediin the plate to make-an airtight seal. The bracket IE0 is moved by-a pie tonmounted in thecylinder 93. Arod 94-conheats the piston to the bracket lilll: The piston is aotuated by air pressurewhich may'becontrolled-ina well known manner; from a remotepo'sition. V

The support-ZI provides vertical support for the tube'Ziiasitis removed ina-manner similarto the SUDPortfurnishedthe tube l l- 0f thecathode... The difference in the cathode diameter of tubes" ll and Zt does notmaterially effect the operationof the support; I

When a new anode has been placed on the track 55,=-the belt 44 is d-riven ina-counter-clock#-" wise-direction'causingthe bracket "49 to push the carriage 54-until the head 2-1: of the anode is within the chamber formed byi the m'ember 59.

After the door 83 has been z the gears 18- and 19;

The door 681s a' -p'a r-t' or the anode Y assembly;- and" a" new one is mounted on -each anode. The door- 681s clamped to plate 56': and the pressure is re duced in the chamberbetween the doors sauna 68 by exhaustlinelll. When the pressure is suftl ciently low, thedoor 63is p'ivoted open an'd the anode slid into-place through the gasket/'61 until the-clamping means 5'l'fastenstheplate 32'to th'e plate 56'. The cathodeisthen positioned in the manner previouslydescribed by returning the bracket-'49 to' a position'adjacent the pulley 46" and placing: anew cathode on track 24;:

The cathode lil -operates at a high emission temperature, and it isdesirable to liquid cool the cathode and anode tubes; It-iS also necessary to supply aheating potential to thecathode." A pair of tubes H0 and HI are attachedto a pair of female members 2- which extend through" the plate 55. The plate 32 has a pair of male members- H3 which extend therethrough* and are engage'able with the members H2 when the anode carriage E lis clamped to the plate 55. A pair oftubes l M extend from the members M3 to second female members H 6" mounted through: the plate 29. Second male members HT are mounted on plate 39 and are engageable with the-members H6.

As shown in Figure 7, a pair of tubes Band 2 89 extend from the members: I I1 into'the cathode tube I l. These tubessupply the heating p'o'-" tentialto the filament l8 and also carry aired--- lating fluid for liquid cooling the cathode; The connection members" il2, H3; H6 and H7 are insulated from the'plates-St, 32-, 29 and-3ll and form fluid tight seals when connected.

Figures 3- and 4* illustrate apparatus for automatically removing the anode and cathode from thetr'acks 24' and when they have been with'- drawn from the doc chamber. The apparatus comprises a carriage which has a base plate 6'3 mounted'on wheels H which ride-on tracks 12%; As shown in Figure 1, the tracks l2 ar'e'placed transversely of the frame 35. Driving means, as;-for example an electric motor i3'is mounted on the under side ofthe base 69 and is connected to the wheels H to provide motive power for moving the;- carriage forwardly a'nd rear'ward ly. A generally U-shaped upright member'T- l is mounted on the base 69. A shaft 76 is r'otatably supported in the legs of the support 14 adjacent the upper end. A second driving means-11 is mountedon the base plate 69' and carries a gear 18. The shaft 16' has a" gear 19 rigidly mounted thereto and a chain drive 8! connectsshaft 16 are two pairs of arms Bland 83; Thearms extend outwardly from the shaft' 'ltandter 1 minate in hooks 84' and 86, respectively The

arms

82 and 83 extend from'theshaft 75 adjacent both ends of the U-shaped support 74. The arms may be rotatedrelative to the carriage by the driving means 11. The hooks at theend of the arms are adapted for engaging the cathode and anode structures to-remove them from the tracks- 24 and 55. The-arms may also be used for" plac ing a-new anode or cathode on the track 24; To remove the cathode structure, a pair of arms must be empty and the carriage; is moved on the track 12 until the hookfifi is beneath-the cathodel Driving means H isthen actuateduntil the cathode ispicked up The carriage is'then backed from the member 36 and: the driving means 11' is actuated to move the other pair" of armsinto" position with its new cathode; The carriage is then once again moved toward the Rigidly connected to the" assnoce member 36 until the new .cathode is directly above the track 24 and is lowered thereon by the driving means 11. The are distance between supporting hooks on adjacent arms must be great enough so that when the arms are replacing a cathode, the removed structure does not en age the support 36 on the driving means 43. This is accomplished by making the angle between

arms

82 and 83 sufficiently great. It is sometimes desirable to use more than two pairs of arms so that the anode and cathode may both be changed. This requires four pairs of arms, one pair to carry the new anode, one pair to carry the new cathode, one empty pair to remove the old cathode, and one pair to remove the old anode. Arms may be added to the shaft '16 as desired.

All the motors, doors, and release mechanisms may be actuated remotely by the operator 87 illustrated in Figure 1. The structure for actuating these members is not shown in detail because they are well known to those skilled in the art. For example, the two motors i3 and 1'! carried on the carriage are conventional electric motors, and a suitable electrical connection between these motors and the operator makes it possible for him to control their motion. The same thing is true of the motor 43. Likewise, the release mechanisms 42 and 57 may be actuated by compressed air in a well known manner. The operator 87 can operate the valves from his remote position.

It is seen that this invention provides means for removing the anode and cathode of a cyclotron without the necessity of exposing human being to the residual radiations from the cyclotron. It is to be understood, of course, that the operating mechanism of the cyclotron is turned off during the ion source change, but a lot of residual radiation remains after the magnetic field has been removed and the alternating potential disconnected from the dees.

Although this invention has been described with respect to particular embodiments thereof,

it is not to be so limited as changes and modifications may be made therein which are within the full intended scope, as defined by the appended claims.

We claim:

1. Means for automatically changing the cathode of a cyclotron having an ion source with a first tube received Within a second tube and the cathode filament connected to the end of said first tube comprising, means for moving said first tube longitudinally of said second tube, a movable door for closing the end of said second tube after the said first tube has been withdrawn therefrom, and an air lock formed about the outer end of said first tube.

2. Means for removing the cathode of a cyclotron comprising, driving means connectable with said cathode to move it longitudinally of said cyclotron chamber, an air lock connected to said cyclotron, a door within said air lock movable to seal the opening which normally receives said cathode, and said driving means removing said cathode from said air lock.

3. In a cyclotron having a tubular anode with an upwardly extending portion adjacent the inner end thereof and a tubular cathode received within said anode, means for removing said cathode comprising, a longitudinal track extending outwardly from one end of said cyclotron, a carriage received on said track and connected to the outer end of said cathode, an air lock about 8-, the outer end of said cathode, driving means for moving said carriage along said track, andadoor movable across the open end of said anode after said cathode has been removed therefrom, prior to removing said cathode from said air lock.

4. Apparatus for automatically removing the anode of a cyclotron comprising, acarriage mounted on a longitudinal track extending out from said cyclotron, the anode of said cyclotron connected to said carriage and extending through an air lock to within the confines of said cyclotron, flexible means connected to said carriage for moving it longitudinally of said track, and a door within said air lock movable to an air seal position when the inner end of said anode is within the confines of said airlock.

5. A system according to claim 3 wherein the anode of said cyclotron is connected to a second carriage which is mounted on a second pair of tracks and which is movable by said driving means longitudinally of said track, a second air lock with a second door movable to an air-seal position when the inner end of said anode is within the confines of said second air lock, and said anode movable from said second air lock.

6. Means for automatically removing and replacing the cathode of a cyclotron comprising, a longitudinal cathode connected to a carriage, a longitudinal track extending outwardly from said cyclotron and supporting said carriage, an air lock adjacent the outer end of said cathode, driving means for moving said carriage longitudinally of said track, a second track transverse of said first track, a second carriage mounted on said second track, a plurality of arms extending out from said second carriage, second driving means connected to said second carriage, a first pair of arms on said second carriage engageable with the removed cathode to lift it from said first track, a second pair of arms carried on said second carriage with a new cathode thereon movable to place said new cathode on said first track, and said first driving means engageable with said new cathode to move it through the air lock and into the cyclotron chamber.

7. A system according to claim 6 wherein said first driving means is engageable with a third carriage connected to the anode of said cyclotron to move it through a second air lock out of the confines of said cyclotron.

8. In a system according to claim '7 wherein said second carriage has a third pair of arms for removing said old anode and a fourth pair of arms for placing a new anode on said third pair of' tracks.

9. In a mechanism for automatically removing and changing the cathode of a cyclotron, replacement means comprising, a portable carriage, driving means for moving said carriage, an upright support means on said carriage, a horizontal shaft rotatably supported in said upright means, second driving means connected to said shaft,

and a plurality of arms rigidly attached to said arms and extending therefrom.

10. In apparatus for changing the cathode and anode of a cyclotron, replacement means comprising, a portable carriage, first driving means cyclotron comprising, a cathode extending longitudinally into the dee chamber of said cyclotron, an air lock about the outer end of said cathode, a longitudinal track extending from said cyclotron, a carriage received on said track, driving means connected to said carriage, a support member pivotally mounted between said tracks and movable to a first position to support the free end of said cathode, and movable to a second position below the level of said tracks so that the carriage may pass there-over.

1 Apparatus for changing the cathode and anode of a cyclotron comprising, a longitudinal cathode received within the hollow confines of a longitudinal anode, a first carriage connected to the outer end of said cathode, a second carriage connected to the outer end of said anode, a first airlock mounted on said second carriage and said cathode movable through said first air lock into said anode, a first door within said first air lock movable to seal the end of said anode when said cathode is removed, a second air lock connected to said cyclotron, a second door pivotally supported within said second air lock and movable to close said second air look when the anode has been substantially removed from the cyclotron, driving means engageable with said first and second carriage to move them longitudinally in and out of said cyclotron, and means for closing said first and second doors.

13. In a system according to claim 12, means for removing said cathode and anode comprising, a third movable carriage, second driving means connected to said third carriage for moving it transversely of said cyclotron, a generally upright support mounted on said carriage, a transverse shaft rotatably mounted adjacent the end of said third carriage, third driving means connected to said shaft, a plurality of arms extending from said shaft, and engaging portions at the outer ends of said arms engageable with the cathode and anode.

14. Apparatus for changing the cathode of a cyclotron comprising, a generally tubular cathode extending into the dee chamber of said cyclotron, a movable carriage connected to the outer end of said cathode, driving means connected to said carriage to move it longitudinally of said cyclotron, a hollow anode extending into the dee chamber of the cyclotron with the cathode received therein, a second carriage mounted to the outer end of the anode, a first air lock mounted on the second carriage, a second air lock mounted on said cyclotron, first fastening means connecting said first carriage to said second carriage, second fastening means connecting said second carriage to said cyclotron, driving means engageable with said first and second carriages to move them longitudinally of said cyclotron, and means for actuating said first and second air locks.

15. In a system according to claim 14, a support member pivotally supported on an extending portion of said cyclotron, said support member movable to a first upright position with an engageable portion in contact with the anode or cathode, and movable to a second horizontal position for allowing the first and second carriages to pass there-over.

16. In a system according to claim 14, removing means comprising, a movable base member, generally upright supporting means, second driving means connected to said removing means, a shaft rotatably supported in said upright supporting plurality of arms extending from said shaft, third driving means connected to said shaft, and cathode and anode engaging portions adjacent the ends of said arms to remove and replace cathodes and anodes.

JOHN J. LIVINGOOD. JOHN V. PETERS. ROYAL A. STREETER.

No references cited.