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Sept- 17, 1946-
A. vERHoEl-F
I
2,407,857 `
X- RAY TUB E
Filed Jan. 11,; 194s '
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2,407,857
Patented Sept. 17, 1946
UNITED STATES PATENT OFFICE
2,407,857
X-RAY TUBE
Adrianus Verhoeff, Eindhoven, Netherlands, as
signor to Hartford National Bank & Trust Com
pany, Hartford, Conn., trustee
Application January 11, 1943, Serial No. 472,068
In the Netherlands February 27, 1941
10 Claims.
(Cl. Z50-«143)
2
1
X-ray tubes having a comparatively great mean
load require measures for cooling the anode.
Various means may be used to withdraw heat
from the anode. In tubes for diagnostic work
the operating temperature of the anode must re
main far below the maximum admissible anode
temperature to prevent heat shock. The usual
expedient is to fix a heat conductor to the anode,
for example conductor shaped in the form of a
y
metal rod which extends through the wall of the
tube behind the anode and has a radiating sur
face outside the tube.
With tubes comprising a safety jacket the pres
ence of such a heat radiating member having the
potential of the anode is inconvenient for several l. 5.
reasons and it has therefore previously been sug
gested that the heat transfer should be effected
by radiation from the anode towards that part of
the tube wall which surrounds the anode instead
of being effected by transmission. By this wall
` which is generally maintained at earth potential,
the heat can be readily transmitted to the sur
rounding air or to a cooling medium.
`
Although this means of cooling the anode
yielded satisfactory results thanks to a combina- ‘
tion of various measures it is surpassed in effi
ciency by the arrangement of an X-ray tube ac
which engages the walls of the intermediate space
with slight pressure and transmits the heat from
one wall to the other. This affords good heat
conduction and enables free expansion and con-,
traction due to temperature changes. This re
silient member may be constituted for example
by a cylinder of corrugated sheet metal.
The principle of the invention may be carried
-into practice in various ways, The insulator may
form part of the outer Wall of the tube :and thus
serve to absorb both the electric voltage and the
air pressure.
‘
As an alternative, the insulator may be wholly
arranged within the vacuum of the tube., In this
case, the heat has therefore still to `be conducted
from the insulator to that part of the outer wall
of the tube by which it is surrounded and which
in this case may be of metal. In order to assist
good heat transmission between the insulator and
the tube wall, it is preferable that a resilient
member, for example a metal sleeve of corrugated
sheet metal should be arranged in the manner
mentioned before for the conveyance of the heat
from the anode to the insulator.
The insulator may be made of ceramic mate
rial, for example china. This material is capable
of withstanding heat, may be readily freed from
gases and is Vgenerally a suilicient heat conductor
'
and electrical insulator.
»
‘
In the latter the peripheral surface of the anode
is enclosed by a stationary body constituted 30 In the construction according to the invention
the heat is conducted away by a body which is re
wholly or in part by a high-tension insulator
quired to be a good electrical insulator. Although
having a sufficient heat conductivity and surface
as a rule the heat conductivity of electrical in
of contact with the anode to conduct a quantity
sulators is much less than that of metals, suffi
of heat of at least 100 watts at a temperature dif
cording to the invention.
ference of not more than 300° C. away from the
cient heat can be conducted away in this case by
the insulator due to the fact that the direction
in which the energy ñows off is normal to the
surface and this latter may be made comparatively
large so that but little heat per unit of section
hence not in an axial direction, the body may con
sist wholly of insulating material or may consist 40 needs to be conducted away. Moreover, the heat
has only to traverse a comparatively short path.
of alternating laminae of conducting and insulat
The conditionsare consequently just the reverse
ing materials.
as compared with tubes having a cooler at the end,
It is essential that the insulating material be
because in the latter case the section of the
capable of withstanding the full tension existing
(metal) heat. conductor is much smaller and its
between the anode and earth, said tension being
length is much greater as compared with the tube
about half the operating voltage of the tube.`
according to the invention.
It is dimcult to manufacture and place in posi
In order to increase the surface over which theV
tion an insulator that fits so accurately around
heat dissipation is distributed the anode as a
the anode that a satisfactory heat conducting,
contact may be set up between the wall of the p 50 whole need not be made particularly long but it
is suflicient to shape it into the form of a hollow
anode and that of the insulator. According to
tube, for example a cylindrical tube, which dis
.the invention, this difficulty can be obviated by
sipates the heat and transmits it to the surround
leaving some intermediate space between the
ing body and which comprises a bottom or inter
anode and the insulator and arranging >therein
vanode to the space outside the vacuum of the
tube. The term “wholly or in part” is to be under
stood to mean here that in a radial direction, and
a resilient member of good‘heat conductivity
mediate wall carrying the anode mirror.
2,407,857
3
4
The circumstance that the anode is in heat
conducting contact with a body7 surrounding it
in it, the body 5 is locally thinned at I4, the
may be taken advantage of to cause it to be so
supported by this body that that part of the wall
which seals the tube at the end behind the anode
is not given any mechanical load by the anode
weight. This latter part which thus only serves
for insulation and for sealing the vacuum'must
give passage to the current supply lead of the
anode which may therefore be very thin so that
heat is not conducted away along this path. The
tube end which can be closed by a cable end piece
thus remains cool due to the fact that a direct
heat-conducting connection to the anode is miss
mg.
.For sealing the tube at the ends use may also
be made of disc-shaped glass-like members com
sleeves 4 and 5 have a corresponding aperture
formed in them and the metal wall I comprises
a window closed by a thin small glass plate l5.
The heat is rapidly dispersed about the block
t and thence it is transmitted to the cylinder l.
The latter gives theanode a large surface of con
tact with the resilient sleeve 6 which in turn is in
contact over a large surface with the china part 5.
Although the heat transmitted through each unit section of the part 5 is less than if it were
made of metal the large extensiveness of the sec
tion which contributes towards the conveyance of
heat and the short distance through which the
heat has to be conveyed enable the heat to escape
rapidly.
It is true that the spaces between the anode
and the china part 5 and those between the latter
glass”) which permits metals and insulating ma
and the tube wallare only filled in part 'but the
terials having widely diiïerent coeñ‘icients of ex 20 gripping sleeves è and 5. may be made of a metal
pansion to be sealed together to thereby obtain a
having a much higher specific conductivity than
vacuum-tight seal.
the insulator 5.
In order that the invention maybe clearly
The outside of the wallfi may, if necessary, be
understood _and readily carried into eiîect it will
cooled artiliciallyv by a circulating gaseous or liq
now be set out more fully with reference to the 25 uid cooling medium or by the provision of cool
accompanying drawing in which two forms of
ing ribs.
'
construction of X-ray tubes according to the in
The withdrawal of heat from the wall l to the
vention are shown in section. By means thereof
glass sealing pieces is avoided by the presence of Y
so‘me details obtained by further development of'
thinned` edges l5. ' In addition, radiation of heat
the invention will be mentioned.
30 from the anode to the sealing piece 2- is prevented
' Fig. l is a longitudinal sectional view of an X
bythe bottom Il of the insulator 5'. The current
ray tube having a heat-conducting insulating
lead 9 is so thin and klong that no appreciable
body arranged entirely within the tube.
heat'transmission occurs alongr it. The glass seal
prising finely divided cavities (so-called “sponge
Fig, 2 is a cross-sectional View of the same tube
ing piece 2 and the cable end-piece to be arranged
taken on the plane I-I.
35 thereon are thus safe-guardedV against heating.
Fig. 3 shows a tube in which the heat conduct
' With X-ray'tubes of they construction hitherto
ing insulating body constitutes the outer wall of
in use the anode is supported by the re-entrant
the tube.
glass edge ofthe tube wall.
’
Referring to the drawing, 1 designates an ex
The invention permits‘a sturdier construction
hausted cylindrical metal vessel closed at the ends 40 to be obtained. It enables the anode to be car
by glass sealing pieces 2 and 3. A cylindrical body
5 of electrically insulating material, for example
china or other ceramic material is gripped in the
metal vessel b-y means of a resilient sleeve 4 of
corrugated sheet metal of good heat conductivity',A
for example copper.
The anode of the X-ray tube is gripped within
the body 5 by a likewise resilient sleeve B of cor
rugated plate-shaped material. The anode com
prises a cylindrical part 'lv and a block 8 both of
metal kof good heat conductivity, for example
copper. The cylinder 1 may be shrunk round the
block 3 so as to afford good heat conduction.
The anode has secured to it a supply conductor
ried solely by therside wall of the tube by uniting
the resilient sleeves 4 and'ß and the insulator 5
with the anode and the metal wall l to form an
Aunshakable unit, forY example by gripping, as
shown. The glass part 2 of the wall which seals
the tube at the end' behind the anode is thus not
given any mechanical load by the weight of the
anode and thus the risk of breakage which is al
ways impending in other tubes is averted.
The metal cylindricalV body l is also used for a
further purpose. It is lengthened towards the side
' of the cathode. This arrangement has the Vad
vantage that the part extending to the other side
can be shorter and the heat is more readily' dis
9 _which is passed through the sealing piece 2 55 tributed about the entire length of the cylinder
by means of a small metal disc li) sealed to the
glass. The cathode Il is secured to the sealing
piece 3 and has a normal construction,` details
such as the leading-in wires sealed in the pinch
20 and the filament being therefore omitted in 60
the drawing.
-
because it can flow from the centre to both sides
moreover, the tube acts as a screen against sec
ondary electrons. In order that this function
may be most effective the cylindrical body is pro
vided with a bottom i8 which‘ has, of course,
formed in it an aperture for the passage of the
- When the tube is in use the electrons are pro
beam of cathode-rays. In addition, this aperture
pelled by the electric neld between the two elec
has an upright edge i9 turned towards the anode
trodes at such a speed against the anode mirror
mirror in order also to retain electrons moving
I2 that X rays are generated in situ. Essentially, 65 in a direction at a large angle with the axis of
l however, the energy of the electrons is converted
into heat and secondary electrons are also dis
lodged.
the tube, such as tertiary electrons proceeding
from the inner wall of the cylinder l.
In so far as charged particles may still emerge
The X rays are absorbed for the greater part
`from the discharge space they are retained by the
by the wall of the tube and other parts (all of 70 insulator 5 which for this purpose is lengthened
which are not shown) which jointly surround
towards the cathode side to the extent of sur
the anode and in part may be provided deliber
rounding the discharge path and, for thel avoid
ately for this purpose. A narrow beam of rays
ance of harmfulcharging _may be provided on
is transmitted. For this purpose the cylindrical
the inside with a thin conducting layer.
V
part 1 of the anode 8 has an aperture i3 formed 75
The anode of the X-ray tube shown in Fig. 3
2,407,857
_
is formed by a block 2| and a cylinder 22, the
block 2| carrying the anode mirror 23.
`
Again, the cylinder 22' is mounted
»
_
,
6
bular envelope, an anode member having a, heat
generating portion and being arranged within
said envelope with its peripheral surface adjacent
an in
sulator 25 >by means of a resilient sleeve 24 of
corrugated »sheet metal.
.
4. An X-ray ¿tube comprising an evacuated tu
" to the inner surface of the envelope, and means
The insulator 25 constitutes the envelope of the
tube, and glass sealing pieces 26 and 21 are sealed
to theedges of the insulator at 28 and 29. The
to directly connect the said adjacent surfaces in
heat conducting relationship co-mprising an elec
trical insulating member and a resilient member.;V
insulator may be of china or of similar ceramic
of good heat-conductivity surrounding
anode member and interposed between the
adjacent surfaces, the heat generated at
portion being- transferred to‘said envelope
material to which glass can be fused. The anode
is supported by the insulator 25 only and the seal
ing piece 2E solely serves for vacuum sealing the
envelope and for the leading-through of the sup
ply conductor 3D to the anode. For the purpose
said
said
said
in a
radial direction from the anode member and sub
stantially entirely by conduction through said
of increased safety the insulator may be coated 15
on the outside with a layer of conductive mate
insulating and'resilient members.
the glass Sealing piece 21 is sealed.
ramic sleeve member and a cylindrical corrugat
'
'
5. An X-ray tube comprising an evacuated tu
bular envelope, a hollow cylindrical anode mem
rial (not shown).
a
‘ Similarly, the sealing piece 21 serves solely for
ber having a wall portion provided with an anode
sealing the vacuum and for leading-through of
mirror and being arranged with its peripheral
the supply leads 3l and 32 to the cathode. The 20 surface adjacent to the inner surface of the en
latter are secured to studs which are arranged
velope, and means to directly connect the said
in a metal plate 35 from which they are insulated
adjacent surfaces in heat conducting relation
by glass beads 33 and 34 t0 the edge of which
ship comprising an electrically insulating ce
The cathode shell 36 is supported within the 25 ed sheet-metal member 'surrounding the cylin
insulator 25 in a manner similar to the anode
drìcal anode member and interposed between the
by means of a disc 31 having a bent-over edge
said adjacent surfaces, the heat generated at the
38 which is rendered resilient by the provision of
anode mirror being transferred to `said envelope a
a plurality of slits 39.
in a radial direction from said anode member
The heat produced in the anode in the use of 30 and substantially entirely by conduction through
the tube passes to the cylinder 22 and hence is
said insulating and sheet-metal member.
led by the resilient sleeve 24 through a large sec
6. An X-ray tube comprising an evacuated en
tional surface of the insulator 25 towards the
velope, and a cathode member, an anode mem
outer surface of the tube, where it is dissipated
ber spaced apart and enclosed within said en
by radiation or carried away by other means.
35 velope, said anode member comprising an anode
What I claim is:
mirror, a hollow cylindrical element enclosing
1. An X-ray tube comprising an evacuated
the anode mirror, and means to collect secondary
tubular envelope, an anode member having a
electrons from the anode mirror comprising a
heat-generating portion and being arranged
portion of the cylindrical element extending be
within said envelope with its peripheral surface 40 yond the said mirror towards the cathode mem
adjacent to and spaced from the inner surface of
ber, said cylindrical element being arranged
the envelope, and means to directly connect the
within the envelope with its peripheral surface
said adjacent surfaces in heat conducting rela
adjacent to the inner surface of the envelope, and
tionship comprising a memberof good heat con-Y
means to directly connect _the said adjacent sur- `
ductivity whereby to transfer the heat generat
’faces in heat conducting relationship comprising
ed at said portion to said envelope in a radial di
a member of goed heat conductivity whereby to
rection from the anode member and substan
transfer the heat generatedV at the anode mirror
tially entirely by conduction.
2. An X-ray tube comprising an evacuated tu
bular envelope, an anode member having a heat
generating portion and being arranged within
said envelope with its peripheral surface adja
to said envelope in a radial direction `from said
cylindrical element and substantially entirely by
50 conduction.
1. A'n X-ray tube comprisingy an evacuated cy
lindrical metal envelope, an anode member with
cent to the inner surface of the envelope, and
means to directly connect the said adjacent sur-4
in said envelope comprising a cylindrical metal
sleeve arranged within the envelope with its pe
faces in heat conducting relationship comprising 55 ripheral surface adjacent to the inner surface of
a resilient member of good heat conductivity, the
the envelope, an anode mirror within said sleeve
heat generated at said portion being transferred
and secured to the inner wall thereof, said- anode
to said envelope in a radial direction from the
sleeve having a portion which extends beyond
anode member and substantially entirely by con
the anode mirrorand is provided ‘with an aper
V duction through said resilient member.
ture in the wall thereof adjacent to the anode
3. An X-ray tube comprising an evacuated tu- '
mirror and which comprises a flange portion
bular envelope of electrically insulating and good
having its edge inwardly facing the anode mir
heat-conducting material, an anode member
ror, and means to directly connect the said ad
having a heat-generating portion and being ar
jacent surfaces in heat conducting relationship,
ranged within said envelope with its peripheral 65 said means comprising a cylindrical electrical
surface adjacent to the inner suface of the en
velope, and means to directly connect the said
insulating ceramic member surrounding the
anode member 'and extending beyond the said
adjacent surfaces in heat conducting relation
flange portion thereof, a cylindrical corrugated
ship comprising a resilient member of goOd heat
sheet metal member interposed between and
conductivity interposed between and contacting 70 contacting the adjacently positioned surfaces of
the said adjacent surfaces, the heat generated at
the ceramic and anode members and a cylindri- ‘
said portion being transferredv to said envelope in
cal corrugated sheet metal member interposed
a radial direction from the anode member and
between and contacting the adjacentlyl posi
substantially entirely by conduction through said
tioned surfaces of the ceramic member and the
75 envelope, the heat generated at the said anode
resilient member.
2,407,857
7
8
,
mirror `being transferred to the envelopein a.
radial direction from the anode member and sub- «
stantially entirely by conduction through said
cylindrical corrugated members and said ceramic
member.
-
Y
age supply conductora for »the anode member
passing through said. sealing member, and means
to directly connect the said adjacent surfaces in
heat conducting relationship comprising -a mem.
ber of good heat conductivity whereby to trans
fer the heat generated at .the said portion of the
8. An X-ray tube comprising an evacuated tu
bular envelope, an anode member having aheat
anode member to said envelope in a radial di
`generating portion and being yarranged >within
rection from the anode member and substantial
yëyaid envelope with its peripheral surface >adja
lyventirely by conduction, said supply conductor
cent to and spaced from the inner surface of the 10 having a poor heat conductivity andpreventing
heat conduction from the anode member to said
envelope, said anode member being supported
sealing member.
Y
»
.
within said envelope substantially entirely by the
10. An X-ray tube comprising an evacuated
surrounding portion of the envelope, and means
tubular envelope', an anode member having a
to directly connect the said adjacent surfaces in
heat conducting relationship comprising a mem 15 heat-generating portion and being arranged
within said envelope with its peripheral surface
' ber of good heat conductivity whereby to vtrans
adjacent to and spaced from and electrically in
fer the heat generated at the said portion of the
sulated from .the inner surface >of the envelope,
anode member to the envelope in a radialdirec
and means to directly connect the said adjacent
tion from the anode member and substantially
entirely by conduction.
20. surfaces in heat conducting relationship co-m- Y
prisingv a member of good heat conductivity
9. An X-ray tube comprising an evacuated tu
whereby to transfer the heat generated at said
bular envelope, a sealing member closing one end
of the envelope, an anode member having a heat
generating portion and being arranged within
the envelope with its peripheral surface adja
cent to the inner surface of the envelope, a volt
portion to said envelope in. a radial direction
from the anode member and substantially entire
ly by ccnduction.
Y
v »
‘
ADRIANUS
VERHOEFF.
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