U.S. patent number 3,775,842 [Application Number 05/281,264] was granted by the patent office on 1973-12-04 for method for centering and restraining coils in an electromagnet.
This patent grant is currently assigned to The United States of America as represented by the United States Atomic. Invention is credited to Robert Sheldon, Bruce P. Strauss.
United States Patent |
3,775,842 |
Sheldon , et al. |
December 4, 1973 |
METHOD FOR CENTERING AND RESTRAINING COILS IN AN ELECTROMAGNET
Abstract
A body is centered within a housing and restrained from moving
from such centered position by surrounding the body with a
plurality of flattened like tubes positioned between the body and
the interior walls of the housing and simultaneously expanding the
tubes so as to center the body by filling the tubes with a
hardenable material under pressure. Upon hardening of the material,
the body is restrained from moving from the centered position. The
method is applied particularly to the coils of an electromagnet and
the beam tube of a particle accelerator so centered and restrained
within a tubular electromagnet housing by hydraulically pumping an
epoxy resin under a high pressure into the symmetrically spaced
like tubes which are connected hydraulically in parallel and,
following curing of the epoxy, capping the ends of the tubes to
maintain hydraulic integrity of the system.
Inventors: |
Sheldon; Robert (Geneva,
CH), Strauss; Bruce P. (Downers Grove, IL) |
Assignee: |
The United States of America as
represented by the United States Atomic (Washington,
DC)
|
Family
ID: |
23076593 |
Appl.
No.: |
05/281,264 |
Filed: |
August 16, 1972 |
Current U.S.
Class: |
29/606; 29/421.1;
29/515; 29/602.1; 264/267; 336/60; 336/197; 29/455.1; 29/522.1;
264/266; 335/213; 336/185 |
Current CPC
Class: |
H05H
7/04 (20130101); H01F 7/06 (20130101); H01F
7/202 (20130101); Y10T 29/49925 (20150115); Y10T
29/49879 (20150115); Y10T 29/4902 (20150115); Y10T
29/49805 (20150115); Y10T 29/49073 (20150115); Y10T
29/49938 (20150115) |
Current International
Class: |
H01F
7/06 (20060101); H05H 7/00 (20060101); H01F
7/20 (20060101); H05H 7/04 (20060101); H01f
007/06 () |
Field of
Search: |
;29/606,602,605,421R,455R,522,515 ;336/60,96,197,196,205,185
;174/52R,52PE ;235/210,213 ;264/266,267,245 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lanham; Charles W.
Assistant Examiner: Hall; Carl E.
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. A method of centering and restraining a body within a housing
comprising:
surrounding said body with a plurality of flattened like tubes
between said body and said housing;
filling said tubes simultaneously with a hardenable material under
pressure whereby the tubes expand to center the body within the
housing; and
hardening said hardenable material, thereby restraining movement of
said body from the centered position.
2. A method of centering and restraining a body within a housing
comprising:
positioning said body within said housing;
positioning a plurality of flattened like tubes between said body
and the interior walls of said housing, said tubes being
symmetrically spaced about said body;
connecting said tubes together hydraulically in parallel;
hydraulically pumping epoxy resin under pressure into said tubes
whereby they expand to center said body within said housing and
restrain the body from moving;
curing the epoxy resin to hardness while maintaining the hydraulic
pressure; and
capping the ends of said tubes to maintain the hydraulic integrity
of the epoxy resin, thereby rigidly restraining movement of said
body from the centered position.
3. The method of claim 2 wherein said housing is tubular; said body
consists of a central member extending along the axis of said
tubular housing and a plurality of peripheral members surrounding
said central member and symmetrically spaced about the axis
thereof; and said flattened like tubes are positioned parallel to
the axis of said central member between the interior walls of said
housing and said peripheral members.
4. The method of claim 3 wherein said central member extends
through said tubular housing; said peripheral members are elongated
flattened coils, said coils elongated in a direction parallel to
the axis of said central member; said flattened tubes are
positioned along the elongated segments of said coils; and each
such elongated segment of each coil is in contact with such a
flattened tube.
5. The method of claim 4 wherein said tubular housing is a
ferromagnetic material, said coils are the coils of an
electromagnet, and said central member is a portion of the beam
tube of a particle accelerator.
6. A method of centering and restraining the coils about a central
member in an electromagnet comprising:
positioning said central member within the electromagnet
housing,
positioning said coils within said housing symmetrically about the
periphery of said central member;
positioning a plurality of flattened like tubes between the
windings of said coils and the interior walls of said housing, said
tubes being symmetrically spaced and each such tube essentially
filling the space between the windings and the interior wall of
said housing;
connecting said tubes together hydraulically in parallel;
hydraulically pumping curing epoxy resin under pressure into said
tubes whereby they simultaneously expand to center the coils within
the housing about said central member and restrain the coils from
moving;
curing the epoxy resin to hardness while maintaining the hydraulic
pressure; and
capping the ends of said tubes to maintain the hydraulic integrity
of the epoxy resin whereby the coils are rigidly restrained and
centered in the electromagnet about said central member.
7. The method of claim 6 wherein said electromagnet housing is
tubular and is composed of a ferromagnetic material; said central
member is a square central tube which extends along the axis of
said tubular housing; said coils are flattened and elongated
windings, said coils elongated in a direction parallel to the axis
of said central tube; said flattened tubes are positioned along the
elongated segments of said coils; and each elongated segment of
each coil is in contact with a flattened tube.
8. The method of claim 7 wherein the electromagnet is a quadrupole
magnet having four coils and four flattened tubes; the coils are
positioned such that the windings of each of the four coils
encircle one of the four edges of the square central tube with the
two elongated segments of each coil positioned along adjacent sides
of the square tube; and each of said four flattened tubes are
positioned so as to contact the elongated segments of two adjacent
coils, which two segments lie on the same side of the square
tube.
9. The method of claim 8 wherein said square central tube is a
portion of the beam tube of a particle accelerator and wherein said
electromagnet is cryogenic.
Description
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
This invention relates to a method of centering a body within a
housing and restraining the body from moving within the housing
from the centered position. The invention is directed toward a
method of centering and restraining the coils about a central
member in an electromagnet and is particularly concerned with the
centering and restraining of coils about a portion of the beam tube
of a particle accelerator in a tubular cryogenic electromagnet
housing.
Continuing investigation into the structure of the nucleus and
research in the fundamental particles and their interactions
require particle accelerators capable of producing particle beams
of increasingly greater energies. Concomitant with beams of greater
energies is the need for magnets with greatly increased field
strengths for use in the construction of the new accelerators.
Electromagnets capable of generating the necessary field strengths
required in new accelerators demand increasing amounts of electric
power for satisfactory operation. The accelerators planned and
proposed for future subnuclear investigations will require
electromagnets with field strengths so great that the amount of
electric power needed to generate these field strengths will be
economically prohibitive. A solution to the power demand problem is
the use of superconducting electromagnets which enable the
attainment of the necessary magnetic field strengths with an
economically acceptable electric power demand. The reduction in the
electric power demand is occasioned by the very drastic reduction
in the resistance in the windings of the coils at extremely low
temperatures. To maintain the superconducting properties of the
electromagnet during operation, a cryogenic fluid must be
continuously passed over the coils and in contact with the
windings. Flow paths through the electromagnet immediately adjacent
the coils with free access to the surfaces of the windings must be
provided in construction of the superconducting electromagnet.
It is also essential in the construction of a superconducting
electromagnet that the coils be centered and restrained from
moving. This is extremely important in particle accelerator
application where the beam tube must be centered within the magnet
and the coils properly positioned and centered about the beam tube
and restrained from any movement to achieve and maintain the
desired magnetic field and its consequent effect on the particle
beam within the beam tube. In particular, in a superconducting
quadrupole electromagnet for use in a particle accelerator, it is
paramount that the coils and beam tube be restrained from any
movement as even a slight movement can distort the magnetic field
and permit the particles to drift to the walls of the beam tube,
negating the effect of the quadrupole magnet as it functions to
center the beam within the tube and prevent particles from drifting
from the center of the tube.
Since any movement of the coils can cause an undesirable distortion
of the magnetic field, the coils must be rigidly restrained along
the entire length of the windings. While the coils have been held
in position previously with spacing elements such as brackets or
braces, these do not provide restraint within acceptable tolerances
for high energy accelerator applications. Also it is necessary to
include such braces along the entire length of the windings and to
position and anchor such braces along such a distance within the
small permissible tolerances is extremely difficult. It is also
known to restrain movement of coils by encapsulation with epoxy
resin, such as in transformers. However, encapsulation with epoxy
resin is not adaptable to cryogenic electromagnet applications as
encapsulation would prevent flow of the cryogenic fluid over the
coils. Also the epoxy resin generally is only poured around the
coils and allowed to cure and consequently exerts little force in
centering and positioning the coils or preventing movement prior to
curing. Consequently, it is an object of the present invention to
provide a method for centering and restraining the coils of an
electromagnet.
Particularly, it is an object of the present invention to provide a
method for centering and restraining the coils of an electromagnet
about the beam tube of a high energy particle accelerator.
It is a further object of the present invention to provide such a
method wherein the coils will be rigidly restrained along the
entire length of the winding.
Specifically it is an object to provide such a method of centering
and restraining the coils which will permit the flow of a cryogenic
fluid over the surfaces of the coils in contact with the windings
so as to permit operation of the electromagnet as a superconducting
magnet in extremely high energy particle accelerator
applications.
An additional object is to provide such a method for centering and
restraining the four coils of a superconducting quadrupole
electromagnet used in a particle accelerator.
SUMMARY OF THE INVENTION
In accordance with the present invention a body is centered and
restrained within a housing by surrounding the body with a
plurality of flattened like tubes positioned between the body and
the interior walls of the housing. The flattened like tubes are
simultaneously expanded so as to center the body by filling the
tubes with a hardenable material under pressure. The hardenable
material is subsequently hardened thereby restraining movement of
the body from the centered position.
Further in accordance with the present invention, the coils of an
electromagnet and the beam tube of a particle accelerator are so
centered and restrained within a tubular electromagnet housing. The
flattened like tubes are positioned symmetrically about the coils
and beam tube between the coils and the interior wall of the
housing and are connected hydraulically in parallel. Epoxy resin is
hydraulically pumped into the tubes simultaneously under a high
pressure and the pressure maintained as the epoxy resin cures.
Subsequent to the curing of the epoxy, the ends of the tubes are
capped to maintain the hydraulic integrity of the system.
BRIEF DESCRIPTION OF THE DRAWINGS
An understanding of the various aspects of the invention will
become apparent upon reading the following description of the
invention and with reference to the drawings in which
FIG. 1 is a cross-sectional view of a body centered and restrained
within a housing in accordance with the present invention.
FIG. 2 is an isometric view partially broken away of a particle
accelerator superconducting quadrupole electromagnet in which the
beam tube and coils have been centered and restrained in accordance
with the present invention.
FIG. 3 is a cross-sectional view taken along the line 3--3 of FIG.
2.
DESCRIPTION OF THE INVENTION
In order to facilitate an understanding of the basic aspects of the
present invention, prior to describing the very important
application of the method to the coils of a cryogenic quadrupole
electromagnet in a particle accelerator, the method will be
described generally in relation to centering a body in a housing
and rigidly restraining the body from moving from the centered
position. Referring to FIG. 1 for a description of the general
application of the method of the present invention, there is
illustrated a body 10 which is to be centered and rigidly
restrained within a housing indicated generally at 11. The body 10
is surrounded by a plurality of flattened like tubes 12 which lie
between the body 10 and the interior walls 13 of the housing 11,
there being four such flattened tubes illustrated in FIG. 1. These
flattened tubes 12 are filled with a hardenable material 14 which
is injected under pressure simultaneously into all such tubes. The
like tubes expand under the fluid pressure of the injected
hardenable material 14 and as they expand contact both the body 10
and the interior walls 13 so as to center the body 10 within the
housing 11. The hardenable material 14 is subsequently hardened
thereby restraining any movement of the body 10 from its centered
position within the housing 11.
While it is preferred that the flattened tubes be spaced about the
body symmetrically, it is not essential as other unsymmetrical
configurations are possible which will achieve the desired result
of centering the body as the tubes expand. The particular spacing
arrangement chosen will depend to some extent upon the shape of the
body and the shape of the interior walls of the housing. While in
FIG. 1 the body is shown to be of a square cross-section as is the
interior surface of the housing, the method is equally adaptable to
other shapes. By injecting a hardenable material into a flattened
tube and thereby expanding the tube, the body is centered and
restrained along its entire length. The fluid pressure of the
hardenable material is equalized throughout the tube so that the
restraining force is equal along the entire length of the tube and
the tube expands under the force as a unit so as to center the body
within very close tolerances along the entire length. The force
exerted to restrain the body is considerable as the hardenable
material is injected into the tube under pressure. Injecting the
material into the tubes under pressure of course gives much greater
restraining force than merely pouring the material into the volume
between the body and the housing as would be done in an
encapsulation type procedure.
The method of the present invention is adaptable to many and
various applications. A very important application is centering and
restraining the coils of a cryogenic quadrupole electromagnet about
a portion of the beam tube of a high-energy particle accelerator.
Referring to FIGS. 2 and 3 for a description of this particular
application of the present invention, a cryogenic quadrupole
electromagnet is indicated generally at 20. An outer tubular shell
21 and a series of very tightly compressed washer-shaped
laminations 22 composed of a ferromagnetic material form the
electromagnet housing 23. A square beam tube 24 which is a portion
of the beam tube of a particular accelerator is positioned so as to
extend through the housing 23 along the axis thereof. The four
coils indicated generally by 25 of the quadrupole magnet 20 are
positioned so as to surround the beam tube 24 and are symmetrically
spaced. Each of the coils 25 is flattened and elongated and is
positioned about the beam tube 24 so as to be elongated in a
direction parallel to the axis thereof. As can be seen by
considering a single such elongated coil 26, the windings of each
such coil encircle one edge 27 of the beam tube 24 with the two
elongated segments 28 and 29 of coil 26 positioned along adjacent
sides 30 and 31, respectively, of the beam tube 24, sides 30 and 31
being those adjacent sides which meet to form edge 27. Since each
edge of the beam tube 24 is similarly surrounded by one of the
coils 25, an elongated segment of each of two adjacent coils lies
along each side of the beam tube. Flattened stainless steel like
tubes 32 are subsequently positioned between the windings of the
coils 25 and the interior surfaces of the laminations 22. The
flattened like tubes 32 are symmetrically spaced and extend along
the length of the elongated coils parallel to the beam tube 24.
Each flattened tube 32 lies along and firmly contacts the two
elongated segments which lie along the same side of the beam tube
24, such as elongated segments 28 and 33 which lie along side 30.
Optionally, small lateral braces 34 may be used to approximately
center the coils 25 on the beam tube 24 and to provide some support
for the coils 25 prior to the subsequent steps of the present
method, although the braces are not essential. These braces must be
small and short so that full flow of cryogenic fluid over the
surfaces of the coils will be affected as little as possible. Also
optional and for cryogenic electromagnet application, a spacing
member such as the serpentine spacer 35 may be inserted between the
beam tube 24 and the windings of the coils 25 to permit flow of the
cryogenic fluid between the beam tube and the coils. As is seen in
FIG. 2, the flattened stainless steel tubes 32 are parallelly
connected by appropriate piping 37 to a hydraulic pump 38. The
flattened stainless steel tubes 32 are connected hydraulically in
parallel so that the hydraulic pressure exerted by the fluid pumped
into the tubes 32 is equal in all tubes. Epoxy resin 36 is
hydraulically pumped through the piping 37 under a high pressure by
pump 38 simultaneously into all the flattened stainless steel like
tubes 32. The flattened tubes 32 simultaneously expand under the
hydraulic pressure to center the coils 25 and beam tube 24 within
the electromagnet housing 23 and prevent and movement of the coils
25 from the centered position. The epoxy resin 36 is cured to
hardness while maintaining the hydraulic pressure in the tubes 32.
After the epoxy resin 36 has cured, the ends of the tubes 32 are
capped to maintain the hydraulic integrity of the epoxy resin. The
hydraulically expanded stainless steel tubes 32 rigidly restrain
any movement of the coils 25 about the beam tube 24 from the
centered position within the electromagnet housing 23.
The rigid restraint placed upon the coils about the beam tube by
the hydraulic pressure of the cured epoxy within the stainless
steel tubes prevents any movement of the coils or consequent
distortion of the magnetic field. Since the tubes extend along the
length of the elongated segments of the windings, the pressure and
restraint is exerted along the entire length of the coils rather
than only at intermittent distances as is the case when braces are
used. Since the epoxy is confined to the tubes, ample flow passages
for a cryogenic fluid over the coils are provided.
EXAMPLE
A superconducting quadrupole electromagnet prototype for use in a
particle accelerator was constructed employing the method of the
present invention. The constructed electromagnet was 50 cm in axial
length, the housing being formed from a 15 cm outer diameter
stainless steel tube having 3 mm thick walls and a series of 0.159
cm thick washer shaped laminations having a 6.8 cm inner diameter
and 14.0 cm outer diameter precompressed to a 99.5 percent packing
factor inserted into the stainless steel tube and held in the
compressed position by 3 mm thick end plates welded to the
stainless steel tube. Four flat and elongated coils were wound in
appropriate form to insure precise conductor placement and were
placed upon a 2.5 cm square beam tube having a serpentine spacer
lying along each side to retain flow passages between the coils and
the beam tube. The coils were approximately centered by small
lateral braces which served to temporarily support the coils in
position about the beam tube until final centering and support were
provided by subsequent steps. Four flattened like stainless steel
tubes were then placed between the windings of the coils and the
interior surfaces of the laminations, one flattened tube on each of
the four sides of the beam tube. The tubes were connected
hydraulically in parallel and simultaneously expanded into place by
pumping room temperature curing epoxy resin into the tubes under a
pressure of 400 psi. The coils and beam tube were centered and
locked firmly in place. The pressure was maintained on the epoxy
material throughout its cure cycle thus providing an irreversible
hydraulic restraining mechanism, and the stainless steel tubes were
subsequently capped to maintain the hydraulic integrity of the
system.
* * * * *