US3723785A

US3723785A - Deformable beam transport system with extraction port

Info

Publication number: US3723785A
Application number: US00256051A
Authority: US
Inventors: J Nixon; W Ramler
Original assignee: US Atomic Energy Commission (AEC)
Current assignee: US Atomic Energy Commission (AEC)
Priority date: 1972-05-23
Filing date: 1972-05-23
Publication date: 1973-03-27
Anticipated expiration: 1990-03-27

Abstract

A beam transport device for a particle beam traversing first and second sections of a beam tube includes a pair of bellows each having an end mounted to an associated one of the sections of the beam tube. Interposed of the bellows and sealed to associated ends thereof are a particle-beam-extraction window and a rigid hollow member juxtaposed of the extraction window. Motive means are coupled to provide motion to the extraction window and rigid hollow member whereby they may be respectively aligned with the particle beam upon deformation of the bellows.

Description

United States Patent Nixon et al.

[ 1 1 3,723,785 1 Mar. 27, 1973 [54] DEFORMABLE BEAM TRANSPORT SYSTEM WITH EXTRACTION PORT Inventors: Jack M. Nixon, Wheaton; Warren J.

Ramler, Elmhurst, both of Ill.

The United States of America as represented by the United States Atomic Energy Commission Filed: May 23, 1972 Appl. No.: 256,051

Assignee:

US. Cl. ..313/63, 250/495 B, 313/62,

313/148 Int. Cl. ..H 05h 9/00 Field of Search ..3l3/62, 63, 148; 250/495 B Primary Examiner-Roy Lake Assistant Examiner-Darwin R. Hostetter Attorney-Roland A. Anderson [57] ABSTRACT 6 Claims, 4 Drawing Figures all? I ll EXPE/P/ MEN 7 PAIENTEBMARZ'! I973 SHEET 1 [IF 2 NEW? MMQEEQ DEFORMABLE BEAM TRANSPORT SYSTEM WITH EXTRACTION PORT CONTRACTUAL ORIGIN OF THE INVENTION The invention described herein was made in the course of, or under, a contract with the United States Atomic Energy Commission.

BACKGROUND OF THE INVENTION The present invention relates to particle accelerators and more particularly to a beam transport device for such accelerators. Particles in todays accelerators are generally accelerated either in a circular orbit (as in a cyclotron or synchrotron) or in a straight line (as in a linear accelerator). The particles are 14 in beam tubes, which tubes are partially evacuated to a high vacuum, generally of the order of 2 X Torr. After they have been accelerated, the particles are extracted from the accelerator to effect collisions with targets of interest. As the particles leave the accelerator and progress towards the target, the particle beam deteriorates in quality. That is, the further the distance to the target the poorer the quality of the beam. The quality of the beam degrades in two respects. First, the space charge causes the beam to debunch whereby the beam spreads axially and spreads the pulse apart. Second, the beam also spreads radially. The radial spreading of the beam may be compensated for by inserting refocusing magnets along the beam tube. However, axial spreading of the beam may not be compensated for. Thus, where it is important for the experiment to have minimal axial spreading of the beam pulse, it is desirable to effect the experiment as close to the accelerator as possible. Conversely, where axial spreading of the beam pulse is not particularly important, the experiments may be conducted away from the accelerator using refocusing magnets to maintain minimal radial spreading of the beam pulse. Heretofore, to achieve these two conditions, it has been necessary to disassemble the beam tubes and break the accelerator primary vacuum in order that one may change from a relatively close target to a target far away or, vice versa, to change from a target relatively far away from the accelerator to a target immediately adjacent the accelerator.

It is therefore one object of the present invention to provide a beam transport for a particle accelerator, which beam transport permits the extraction of a particle beam from the accelerator either immediately adjacent the accelerator or removed therefrom.

It is another object of the present invention to provide an improved beam transport device for use in a particle accelerator.

It is another object of the present invention to provide a beam transport device enabling extraction of the beam either immediately adjacent the accelerator or removed therefrom without interruption of the primary vacuum system of the accelerator.

Other objects of the present invention will become more apparent as the detailed description proceeds.

In general, the beam transport device for a particle beam traversing partially evacuated axially aligned spa tially disposed first and second sections of a beam tubecomprises particle-beam-extraction-window means and a first hollow member internally sized to accept said particle beam and juxtaposed said beam-extractionwindow means. A deformable second hollow member is provided internally sized to accept said particle beam therethrough and at one end to accept said beam-extraction-window means and the first hollow member in juxtaposed relationship. Means mount the said one end of the deformable second hollow member in sealed engagement to the beam-extraction-window means and one end of the first hollow member and also mount the other end of said deformable second member in sealed engagement to the first section of the beam tube to pass said particle beam therethrough. A deformable third hollow member is provided internally sized to accept the particle beam and means mount one end of the deformable third hollow member in sealed engagement to the other end of the first hollow member and also mount the other end of the deformable third hollow member in sealed engagement to the second section of the beam tube to pass the particle beam therethrough. Motive means provide motion to the first hollow member and the beam-extraction-window means to permit alignment therebetween with the particle beam.

BRIEF DESCRIPTION OF THE DRAWINGS Further understanding of the present invention may best be obtained from consideration of the accompanying drawings wherein:

FIG. 1 is a sectional view of an apparatus for the practice of the present invention.

FIG. 2 is a section through the apparatus of FIG. 1 along the lines 2-2;

FIG. 3 is an enlarged section of FIG. 2 along lines 3 FIG. 4 is a view of the apparatus of FIG. 1 showing the apparatus in a different positional location than in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. 1-4 show an apparatus for the practice of the present invention as applied to a particle accelerator beam 10 emerging from an accelerator via a beam tube I 12. For the practice of the present invention, the beam tube 12 is divided into two portions, the first beam tube portion 14 and a second beam tube portion 16. The beam transport device 17 of the present invention is inserted between these two

portions

14 and 16 of beam tube 12.

The beam transport apparatus 17 comprises a pair of bellows 18 and 20 whose ends are terminated in

flanges

22, 24, 26 and 28, respectively. A plate 30 having an aperture 32 therethrough sized to accept the end portion 14 of beam tube 12 is mounted on the end portion 15 of beam tube 12 and welded thereto to provide a seal therewith. Further, the plate 30 issized to engage the flange 24 of bellows l8 and a weld is effected therebetween to provide a seal between the bellows flange 24 and plate 30. Similarly, a plate 34 having an aperture 36 therethrough sized to accept the end portion 16 of beam tube 12 is mounted on the end portion 16 of beam tube 12 and a weld is effected therebetween to seal the plate 34 about the end portion 16 of beam tube 12. The plate 34 is sized to engage the flange 28 of bellows 20 and a weld is effected therebetween to provide a seal between the plate 34 and flange 28 of bellows 20.

A plate 38, having two

apertures

40 and 42 therein sized to accept a particle-beam-extraction window 44 and a hollow beam tube 46 in juxtaposed relationship with respect to each other, is mounted so that it engages the flange 22 of bellows 18. A butt weld is effected between the flange 22 of bellows l8 and the plate 38 to effect a seal therebetween. The beam tube 46 is internally sized to accept the particle beam and is disposed within the aperture 42 of plate 38. A weld is effected between the plate 38 and the beam tube 46 to form a seal therebetween. The window 44, as shown in FIG. 3, comprises a window frame 48 housing a foil 50 which is transparent to the beam 10 but maintains the partial vacuum of the accelerator. The window frame is mounted to the plate 38 so as to effect with an O-ring seal 49 a scalable engagement therewith about aperture 40. A plate 52 having an aperture therethrough positioned and sized to accept the beam tube 46 extending from plate 38 is sized to engage the flange 26 of bellows 20. A butt weld is made between the flange 26 of bellows and the plate 52 to effect a seal therebetween. Similarly, a weld is made about the beam tube 46 and the plate 52 to effect a seal therebetween.

A rigid U-frame member 56 is mounted to the

plates

52 and 38 and a motive device, such as an air cylinder 58, is mechanically coupled to the U frame 56 to provide reciprocating motion normal to the axis of the beam 10. Thus, movement of the piston of the air cylinder 58 imparts reciprocating motion to the beam tube '46 and the window 44 to permit the positioning of the window 44 or the beam tube 46 in line with the axis of the beam 10.

In operation, the air cylinder 58 is actuated to provide linear motion to the beam tube 46 and window 44 normal to the axis of the beam 10. Depending upon whether extraction of the beam is desired immediately adjacent the accelerator or downstream from the accelerator, the air cylinder 58 is actuated to move the window 44 or the beam tube 46 in line with the axis of the beam 10.

FIG. 1 illustrates the air cylinder 58 actuated to align the window 44 with the beam 10 to permit extraction of the beam 10 immediately adjacent the accelerator.

FIG. 4 illustrates the air cylinder 58 actuated to align the beam tube 46 with the beam 10 to permit the beam 10 to progress downstream from the accelerator.

It will be appreciated that these two conditions, namely extraction of the beam immediately adjacent the accelerator or transmission of the. beam downstream from the accelerator, are accomplished using the structure of the present invention without disconnecting any beam tubes or affecting the primary partial vacuum of the accelerator. It will be further appreciated that using the structure of the present invention the duty factor of experiments on an accelerator is markedly increased, since no lost time is effected in changing beam tubes or losing the vacuum.

The structure of the present invention has been successfully constructed and utilized on a linear accelerator. It is not restricted to linear accelerators and may be used on other types of accelerators. With the linear accelerator using a 3-inch diameter beam tube 12, the bellows l8 and 20 were each made of stainless steel and had an internal diameter of6 inches and an unextended length of 6 inches. The beam tube 46 was of stainless window means steel and had a length of 14 inches and an internal diameter of 3 inches to accommodate the beam 10. The window 44 had an effective window diameter of approximately two inches and utilized l-mil double aluminum foils transparent to the beam 10. The

plates

30, 34, 38 and 52 were also of stainless steel. The aforedescribed sizes permitted a lateral radial motion of approximately 3 k inches, permitting the alignment of the accelerator beam 10 either through the window 44 or the hollow beam tube 46. It will be appreciated that the relative lengths of the bellows l8 and 20 and the beam tube 46 may be changed to permit greater lateral radial movement or greater area for experimental equipment between the bellows l8 and 20.

Persons skilled in the art will, of course, readily adapt the teachings of the present invention to structure far different than those illustrated in the drawings and described above. Accordingly, the scope of protection afforded the present invention should be determined only in accordance with the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A beam transport vdevice for a particle beam traversing partially evacuated axially aligned spatially disposed first and second sections of a beam tube comprising particle-beam-extraction-window means, a first hollow member juxtaposed of said beam-extractionwindow means and internally sized to accept said particle beam, a deformable second hollow member internally sized to accept said particle beam therethrough and at one end to accept said beam-extraction-window means and first hollow member in juxtaposed relationship, means for mounting the said one end of said deformable second hollow member in sealed engagement to said beam-extraetion-window means and one end of said first hollow member, means for mounting the other end of said deformable second member in sealed engagement to said first section of said beam tube to pass said particle beam therethrough, a deformable third hollow member internally sized to accept said particle beam, means for mounting one end of said deformable third hollow member in sealed engagement to the other end of said first hollow member, means for mounting the other end of said deformable third hollow member in sealed engagement to said second section of said beam tube to pass said particle beam therethrough, and means for providing motion to said first hollow member and said beamextractionto permit respective alignment therebetween with said particle beam.

2. The apparatus according to claim 1 wherein said deformable second member and said first hollow member and beam-extraction-windowmounting means comprises a bellows internally sized to accept said first hollow member and said beam-extraction-window means in juxtaposed coextensive relationship from one end thereof, and a plate sealably disposed about each,

of said first hollow member and beam-extraction-window means and sealably mounted to said one end of said bellows. v

3. The apparatus according to claim' 1 wherein said deformable third hollow member comprises a bellows internally sized to accept said particle beam therethrough.

4. The apparatus according to claim 1 wherein said motion means comprise motive means reciprocativally operable substantially normal to the axis of said particle beam and coupling means connecting said motive means to impart reciprocal motion to said first hollow member and said beam-extraction-window means to permit the respective alignment thereof with said particle beam.

5. The apparatus according to claim 1 wherein said deformable second and third hollow members and said sealing means therefor comprise a first bellows internally sized to accept said first hollow member and said beam-extractiomwindow means, a first plate sealably mounted about said first portion of said beam tube and to one end of said first bellows, a second plate sealably mounted about one end of said first hollow member and said beam-extraction-window means and to the other end of said first bellows, said first hollow member and said beam-extraction-window means being juxtaposed and coextensive from said second plate, a second bellows internally sized to accept said particle beam, a third plate sealably mounted about said first hollow member and to one end of said second bellows, and a fourth plate sealably mounted about said second section of said beam tube and to the other end of said second bellows.

6. The apparatus according to claim 5 wherein said first hollow member and beam-extraction-window moving means comprise motive means disposed to provide reciprocative motion essentially normal to the axis of said particle beam, and means connected between said motive means and said second and third plates to translate said reciprocative motion to said first hollow member and said beam-extraction-window means and effect respective alignment thereof with said particle beam.

Claims

1. A beam transport device for a particle beam traversing partially evacuated axiaLly aligned spatially disposed first and second sections of a beam tube comprising particle-beamextraction-window means, a first hollow member juxtaposed of said beam-extraction-window means and internally sized to accept said particle beam, a deformable second hollow member internally sized to accept said particle beam therethrough and at one end to accept said beam-extraction-window means and first hollow member in juxtaposed relationship, means for mounting the said one end of said deformable second hollow member in sealed engagement to said beam-extraction-window means and one end of said first hollow member, means for mounting the other end of said deformable second member in sealed engagement to said first section of said beam tube to pass said particle beam therethrough, a deformable third hollow member internally sized to accept said particle beam, means for mounting one end of said deformable third hollow member in sealed engagement to the other end of said first hollow member, means for mounting the other end of said deformable third hollow member in sealed engagement to said second section of said beam tube to pass said particle beam therethrough, and means for providing motion to said first hollow member and said beam-extraction-window means to permit respective alignment therebetween with said particle beam.

2. The apparatus according to claim 1 wherein said deformable second member and said first hollow member and beam-extraction-window mounting means comprises a bellows internally sized to accept said first hollow member and said beam-extraction-window means in juxtaposed coextensive relationship from one end thereof, and a plate sealably disposed about each of said first hollow member and beam-extraction-window means and sealably mounted to said one end of said bellows.

3. The apparatus according to claim 1 wherein said deformable third hollow member comprises a bellows internally sized to accept said particle beam therethrough.

5. The apparatus according to claim 1 wherein said deformable second and third hollow members and said sealing means therefor comprise a first bellows internally sized to accept said first hollow member and said beam-extraction-window means, a first plate sealably mounted about said first portion of said beam tube and to one end of said first bellows, a second plate sealably mounted about one end of said first hollow member and said beam-extraction-window means and to the other end of said first bellows, said first hollow member and said beam-extraction-window means being juxtaposed and coextensive from said second plate, a second bellows internally sized to accept said particle beam, a third plate sealably mounted about said first hollow member and to one end of said second bellows, and a fourth plate sealably mounted about said second section of said beam tube and to the other end of said second bellows.