U.S. patent number 3,678,328 [Application Number 04/772,556] was granted by the patent office on 1972-07-18 for channel multiplier assembly and method of manufacture thereof.
This patent grant is currently assigned to The Bendix Corporation. Invention is credited to Fred H. Cross, Bagdasar Deradoorian.
United States Patent |
3,678,328 |
Cross , et al. |
July 18, 1972 |
CHANNEL MULTIPLIER ASSEMBLY AND METHOD OF MANUFACTURE THEREOF
Abstract
A bundle of individual channel multipliers stacked to form a
multiplier array, the individual channels being fabricated of a
lower temperature softening glass and the bundle being inserted
into a higher temperature softening glass tube, the walls of the
individual channels being expanded to fill the interstices within
the higher softening temperature tube.
Inventors: |
Cross; Fred H. (Birmingham,
MI), Deradoorian; Bagdasar (Detroit, MI) |
Assignee: |
The Bendix Corporation
(N/A)
|
Family
ID: |
25095476 |
Appl.
No.: |
04/772,556 |
Filed: |
November 1, 1968 |
Current U.S.
Class: |
315/12.1;
313/105CM; 250/214VT; 313/105R; 250/214LA |
Current CPC
Class: |
H01J
43/24 (20130101); C03B 37/028 (20130101); C03B
2203/10 (20130101); C03B 2203/06 (20130101); C03B
2203/20 (20130101); C03B 2203/16 (20130101) |
Current International
Class: |
H01J
43/00 (20060101); H01J 43/24 (20060101); C03B
37/02 (20060101); C03B 37/028 (20060101); N01j
029/41 () |
Field of
Search: |
;331/95,65 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Borchelt; Benjamin A.
Assistant Examiner: Moskowitz; N.
Claims
What is claimed is:
1. A channel multiplier array comprising a central core of a
plurality of integrally formed individual channels fused together
and having an interior electron emitting surface and fabricated of
a first temperature softening material and an outer jacket
surrounding said central core and fused thereto, fabricated of a
second higher temperature softening material.
2. The improvement of claim 1 wherein said central core further
includes a centrally disposed core fused to said plurality of fused
individual channels.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
This invention relates generally to a channel multiplier array and
a method of producing the array, and more particularly to a method
of expanding the individual channels within an outer glass jacket
to fill the interstices between the individual channels and between
the channels and the outer tube and the resulting apparatus.
Early uses of electron multipliers involved the provision of a
plurality of individual glass channels formed of straight-through
tubes, the individual channels being stacked in a bundle to form an
array. This array was utilized, for example, to multiply the number
of electrons introduced at the input end of the channel multiplier
array by means of secondary emission of electrons from the interior
surface of the channels. Thus, an electron introduced into one end
of the channel multiplier will successively strike the interior
wall of the individual channels, knocking off secondary electrons
to increase the number of output electrons relative to the number
of input electrons.
However, it has been found that spurious outputs are produced by
ion, in the case of an electron multiplier array, or photon
feedback, these phenomena involving the feedback of ions or photons
from the output end of the channel multiplier array to the area of
the input end, the ion feedback producing a direct secondary
multiplication effect and the photons causing the release of
electrons from a photocathode surface. This feedback effect has
been eliminated by several methods, one of which is described in
copending application of Messrs. William Balas and Bagdasar
Deradoorian, Ser. No. 772,527 filed Nov. 1, 1968 for Spiraled
Channel Multiplier Assembly and Method of Assembly. In accordance
with the disclosure of the aforementioned copending application, a
plurality of individual channels are formed into a bundle and fed
through a heating oven for drawing the channels to a particular
size. During the drawing process, the bundle is given a twist by
rotating either the feed or the pull apparatus under controlled
conditions to impart a predetermined spiral to the bundle. Thus,
the array is simultaneously sized and spiraled by means of a single
machine.
However, in providing a bundle of channel multiplier elements in
the form of an array, it has been found that the open area ratio or
the ratio of the useful area to the total area available in the
array may be substantially increased by the expansion of the walls
of the elements within the confines of an outer tube. In accordance
with the present invention, the bundle of individual channels may
be formed as described in the copending application and the
resultant spiraled array may be placed inside an outer glass tube,
the tube being formed of a high temperature softening material
relative to the material of the individual channels. Thus, when the
assembly is heated, the outer jacket glass will soften at a
temperature which is higher than the softening temperature of the
individual channel multiplier elements.
In accordance with a preferred form of the present invention, a
channel multiplier array is sealed at one end thereof and the other
end remains open to the atmosphere. The interstitial space and the
space between the array and the outer jacket is sealed at one end
and the vacuum is drawn at the other end thereof. The entire
assembly is then heated and the difference in pressure between
atmosphere and the vacuum being drawn causes the walls of the
channel multiplier bundle to move outwardly thus decreasing the
wall thickness, filling the interstitial spaces and generally
increasing the useful or open area of the array relative to the
total area. In this way the collection efficiency of each
individual channel multiplier element and the resultant array is
greatly increased.
By use of the present invention, a spiraled channel multiplier
array may be made cylindrical by fabricating a spiral array,
inserting the array within a circular outer jacket and expanding
the array to fill the interstitial spaces within the jacket. With a
round exterior periphery, a plurality of the channel multiplier
arrays may be bundled together to form an array assembly which is
relatively compact, has a relatively high open area ratio and an
increased efficiency.
Accordingly, it is one object of the present invention to provide
an improved channel multiplier array.
It is another object of the present invention to provide an
improved channel multiplier array wherein the individual channels
are spiraled to eliminate feedback effects.
It is further object of the present invention to provide an
improved channel multiplier array assembly, the assembly being made
up of a plurality of channel multiplier arrays.
It is still a further object of the present invention to increase
the open area ratio or ratio of open area to total area in a
channel multiplier array or a channel multiplier array
assembly.
It is still another object of the present invention to improve
channel multiplier arrays by decreasing the wall thickness of the
individual channel while maintaining the total mechanical strength
of the array.
It is still a further object of the present invention to provide an
improved method of filling the interstitial spaces in a channel
multiplier array.
Further objects, features and advantages of this invention will
become apparent from a consideration of the following description,
the appended claims and the accompanying drawing in which:
FIG. 1 is a schematic diagram illustrating a preferred method of
forming a channel multiplier array in accordance with the present
invention;
FIG. 2 is an end elevation illustrating a bundle of individual
channel multipliers;
FIG. 3 is an end elevation illustrating the bundle of channel
multipliers after it has been placed inside the high temperature
softening glass tube;
FIG. 4 is a diagram schematically illustrating an apparatus for
practicing the method of the present invention;
FIG. 5 is a sectional view illustrating the resultant channel
multiplier array in cross section; and
FIG. 6 is an elevation view illustrating the side of the channel
multiplier array of FIG. 5.
Referring now to the drawings, there is illustrated a preferred
method of forming a multiplier array incorporating the features of
the present invention. Particularly, a plurality of individual
channel elements 10, which may number from two to several depending
on the diameter of elements and the total diameter, are formed in a
bundle 12 so that each individual channel element 10 is positioned
within the bundle in the same relative position with respect to all
of the other elements within the bundle at each point along the
linear length of the channel elements. The bundle of channel
elements is placed in an apparatus such as that described in
conjunction with the above referenced copending application.
In accordance with the aforementioned application, the bundles are
placed in a sizing and spiraling assembly whereby the bundle is
inserted into and extends through an oven to heat the bundle and
draw the elements to size. The feed portion or the pull portion of
the apparatus, as described in the aforementioned application, may
be twisted to form a spiral in the bundle and eliminate ion or
photon feedback from the multiplier assembly after it has been
placed into use. After the bundle 12 has been formed and sized, it
is placed in an outer jacket 14 of glass or other material as is
illustrated in FIG. 3 of the drawings. It is to be noted that in
FIGS. 2 and 3 a core 16 or cane has been placed in the interior
portion of the individual bundles and the individual elements may
be spiraled about the cane 16 in a manner known in the art.
However, if the method of the copending application is utilized,
the cane or support element may be eliminated, thus increasing the
efficiency of the array.
The outer jacket 14 is formed of a higher temperature softening
glass than the glass from which the elements 10 have been
fabricated to permit the entire assembly to be heated to a
temperature above that at which the bundle 12 will soften but below
that at which the outer jacket 14 will soften.
The entire assembly, including bundle 12 and outer jacket 14 is
placed in a heater 20 (FIG. 4) which may take the form of an
electrical coil to heat the channel element assembly. However,
prior to positioning the bundle in the heater 20, one end of the
outer jacket 14 is sealed by some suitable method, for example by
placing the ring 22 of temperature resistant material at one end
thereof and surrounding the bundle 12. The ring 22 is to the outer
jacket 14 and to the inner bundle 12, care being taken to preclude
the sealing of the right end of bundle 12. The opposite end of the
tube 14 is interconnected with a vacuum pump which is capable of
evacuating the space between the bundle 12 and shell 14.
Further, the end of bundle 12 which is positioned between the seal
22 and the vacuum pump 24 is also sealed to preclude the evacuation
of the volume within the inside diameter of the individual elements
of the bundle 12. The other end of the bundle 12, the right end in
the assembly illustrated, is left open to the atmosphere.
Upon completion of the assembly illustrated in FIG. 4, the vacuum
pump is actuated to evacuate the volume described above and the
heater assembly 20 is energized to soften the bundle 12. When the
temperature reaches the softening point of the bundle 12, the
pressure differential across the wall of the individual channel
elements within bundle 12 will cause the elements to expand and
fill the interstitial spaces between the elements of the bundle 12
and between the bundle 12 and the exterior jacket 14. The resultant
channel multiplier array is illustrated in FIGS. 5 and 6.
As is seen from FIG. 5, the walls of the individual element have
expanded outwardly to combine and fuse with the outer jacket 14 and
form an integral mass therewith. Similarly, the interior walls have
expanded to meet the interior walls of other elements and also have
expanded to meet the cane element 16, in the situation where a cane
is utilized, the spaces therebetween are completely filled. In this
way a channel multiplier array has been formed which has a high
ratio of a useful area to total area at a cross section thereof,
thus increasing the efficiency of the channel multiplier array.
Also, the exterior surface of the array is cylindrical to
facilitate assembling several arrays and increasing the overall
efficiency of the final assembly.
While it will be apparent that the embodiments of the invention
herein disclosed are will calculated to fulfill the objects of the
invention, it will be appreciated that the invention is susceptible
to modification, variation and change without departing from the
proper scope or fair meaning of the subjoined claims.
* * * * *