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Патент USA US3043996

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July 10, 1962
R. w. HAEGELE ET AL
3,043,985
REFLEX KLYSTRON
Filed March 18, 1959
2 Sheets-Sheet 2
J‘
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.L A
‘we
INVENTORS
ROWLAND w. HAEGELE
OSKAR HEIL
BY CARL 11. TURNBLOM
t—~ W
ATTORNEYS
Statea
atent
l .
2
3,0433%
apparent from the following description when taken in
conjunction with the accompanying drawings. The in
REFLEX KLYSTRON
vention is not limited to the embodiment disclosed, as
Rowiand W. Haegeie, Manic Park, and Oshar Heil, San
lilateo, Calif., and Carl H. Turnblom, Salt Lake City,
Utah, assignors to Eitel-McCullongh, Inc, San Bruno,
variant embodiments may be adopted within the scope
. of the claims.
FIGURE 1 is a sectional view of the re?ex klystron
taken
on line 1-—1 of FIGURE 2;
Filed Mar. 18, 1959, Ser. No. 890,178
FIGURE 2 is a sectional view of the re?ex klystron
7 Claims. (Cl. SIS-4.21)
taken on line 2-2 of FIGURE 1.
Referring to FIGURE 1 of the drawing, there is shown
This invention relates to improved re?ex klystron tubes 10
a re?ex klystron tube with a cathode header assembly
and, more particularly, to a re?ex klystron having im
12, a repeller header assembly 14, a tubular body 16, a
proved power output over a broad frequency range.
tuning assembly 17, an output waveguide assembly 18,
A re?ex klystron comprises an electron gun, an inter
and a resonant cavity 20‘.
action gap surrounded by a resonant cavity, and a re
Calif., a corporation of California
~23
The cathode ‘header assembly 12 has a disk-shaped ce
peller electrode. The electron gun produces an electron 15
ramic header 22 with eight metal prongs 24 disposed in
beam which is projected across the interaction gap to
a circle protruding through and brazed to the header 22.
ward the repeller electrode. In crossing the interaction
A larger center prong 26 with an index key 28 is disposed
gap certain of the electrons in the beam will be accelerated
at the center of the array of the eight prongs 24, and
and other electrons will be decelerated by electromag
' netic oscillations in the cavity surrounding the gap. The 20 on the klystron axis. A sealing ring 3%‘ of U-shape
cross-section is brazed to the periphery of the ceramic
electrons proceed on toward the repeller electrode, where
header ‘22.
'
they are re?ected back across the interaction gap during
the course of which the fast electrons will catch up with
the slow electrons to form bunches. The bunches of
The electron gun for the re?ex klystron is assembled
on the cathode ceramic header in the following manner:
electrons will add to the electromagnetic oscillations in 25 a cathode mounting bar 32 with upturned end ?anges is
attached to two opposite prongs 24 and disposed ?at
the cavity as they recross the interaction gap. Output
against the inside face of ceramic header 22. A stepped
power is coupled from the cavity through a high fre
tubular cathode support 34 is welded :to the mounting
quency output window in the cavity well.
bar’ 32 by an inward ?ange disposed on the small end
Since the operating frequency of klystrons in general is
determined by the resonant frequency of the cavity sur 30 of the support 34 and is disposed coaxially with the klys
tron axis. A thin tubular heat shield 36'which supports
rounding the interaction gap and the resonant frequency
at one end a dished cathode 38 is welded at its other end
to the cathode support 34. The concave side of the cath
ode 38 is coated with an electron emissive oxide such
therefore the volume of the resonant cavity is small, in 35 as barium oxide and faces the repeller assembly 14. The
cathode is an indirectly heated type and is heated by a
the order of one cubic inch. Since it is di?icult to change
of the cavity is determined by the cavity volume, smaller
volumes will resonate at higher ‘frequencies. Re?ex klys
trons operate in the range of 10,000 megacycles, and
a small volume with any degree of ?neness, re?ex klys
trons are made to operate at a ?xed frequency.
The
frequency may be changed slightly in order to match a
given system by such means as deforming the cavity box
by applying a force to the cavity box and not exceed
helical ?lament 40 disposed within the cathode 38 and
heat shield 36. The ?lament 40 is' supported by two
L-shaped rod lead-ins ‘42 which protrude through two
ports 44 in the side of the cathode support 34. The lead
ing the yield strength of the material the cavity is made
ins are welded to two other adjacent prongs 24. For
more efficient cathode heating a ceramic disk 46 is dis
from.
posed transversely within the cathode support 34 and
'
It is an object of the present invention to provide a 45 ?xed to the stepped section, as illustrated. An outwardly
?anged tubular metallic heat conductor 43 is disposed
re?ex klystron with a broad-frequency range and with
around the ?lament and ?xed to the convex side of the
?ne tuning over the frequency range.
cathode by its ?ange.
Since the re?ex klystron is small and compact, no
A stepped tubular electron beam focusing support 50
axially aligned magnetic ?eld is used for electron beam
guidance. Consequently the electrons tend to drift away 50 is welded by its smaller end to heat shield 36 around
the cathode support 34. Two rings 52 and 54 of L
from each other and become ineffective in producing
shaped cross-section are welded, respectively, internally
power output. This is one of the features which make
and externally of the focusing support 50 spaced from
a re?ex klystron a low ef?ciency apparatus.
each other and disposed coaxially on the klystron axis.
It is another object of the present invention to provide
The internal diameter of the focusing support is larger
a re?ex klystron with higher e?’iciencies.
'
55
than the cathode diameter. The ?rst ring 52 has an in
It is a further object of the present invention to increase
ternal diameter equal to the cathode diameter and is
‘ the number of bunched electrons re?ected back through
spaced axially from the cathode 38‘. The second ring
the interaction gap in phase with each other.
54‘ having the same internal diameter as ring 52 is spaced
It is a still further object of the present invention to
a greater axial distance from the cathode 88. This spac
provide a re?ex klystron of ceramic-to-metal structure.
ing, the shape of the anode, and the location of the anode
The present invention provides an improved re?ex klys
determine the beam focusing and beam perveance.
tron with high e?iciency, a broad frequency range with
On the body 16 are machined external circumferential
?ne tuning, and a relatively high‘power output. The
cooling ?ns 56. The internal cylindrical surface of the
above characteristics are produced according to the sub
ject invention by the following features: a ceramic tuning 65 body 16 is- machined to the concentric stepped bores for
accurately disposing of internal parts of the re?ex klystron
slug insertable into the cavity, a gridless electron gun with
‘improved focusing characteristics, improved ?at, ?xed,
tube. A ?rst bore 58 having a diameter larger than the
focusing support 50‘ is disposed at the cathode end of
body 16. The second larger bore 60 is located at the
the greatest number of bunched electrons in phase with 70 center of the body 16. A drift tube anode 62 with an
external flat ring 63 is press ?tted Within bore 60 against
each other through the interaction gap.
the step thereof. A larger third bore 64 extends into
These and other objects of ‘the invention will become
radial-vane interaction gap grids, and a re?ector electrode
with an improved repeller surface contoured to return
3,043,985
3
the body 16 at the repeller end. A disk 66 with a center
port 67 is pressed therein against the step, completing the
resonant cavity 20. Sealingrings 68 and 68' of Z-shaped
A.
and the repeller header assembly 14 are accurately as
sembled individually and then sealed to body 16 by arc
welding together the adjacent edges of sealing rings 30
cross-section are brazed to the ends of body 16 which
and 68 and of sealing rings 30' and 68’. The design of
is counterbored at each end to accommodate the ?anges
on the sealing rings 68 and 68’.
'
the body 16 and header assembly 12 and 14- insures ac
The waveguide assembly 18 is mounted perpendicular
ly to the body 16 through a machined rectangular port
70. A waveguide'71 is brazed to and protrudes through
curate positioning of the electrode within the body 16.
In operation, the ?lament 40‘ heats the cathode 38,
and electrons are emitted from the coated concave sur
face. The electrons are attracted by the positive potential
the port 70 so that a ?at plate 72 welded to the inner 10 on drift tube anode 62. The spacing of the rings 52 and
end lies totally within the bore of the body 16. The
?at plate 72 has an output port 74 communicating with
the resonant cavity 20. A ?at ceramic output window
54, cathode 38 and anode 62 from each other forms the
focusing electric ?eld which concentrates or focuses the
electrons near the beam axis. One end 132 of the drift
tube anode 62 is placed close to the cathode to attract
75 is brazed to plate 72 over the port 74 making a
vacuum seal. A “sandwich” type metal-to-ceramic bond 15 the greatest number of electrons without a?ecting the
focusing ?eld, thus producing a high perveance beam.
76 is used for this seal to withstand high thermal stresses.
The higher the perveance the greater is the available
The sandwich bond 76 is made by machining an annular
output power of the klystron for a given beam voltage.
step on the window 75 and brazing a metal sealing ring
'In this embodiment of the invention, a simple geometric
78 of- L-shaped ‘cross-section to this stepped portion.
An annular ceramic backing ring 82 is brazed on the 20 shape machined anode having a drift tube section as
shown produces the best practical beam. The end 132
opposite side of the sealing ring 78. As seen in the draw
of the drift tube 62 was made to protrude through ring
ing, both faces ‘of the ceramic windows are ?at and the ‘
_ 63 towards the cathode. The bore of the drift tube
external face is ?ush with the ceramic ring 82. A ?ange
was made of two diameters with the smaller diameter '
83 on the sealing ring 78 is then brazed to the plate 72.
The waveguide 71 has a standard coupling ?ange 84 on 25 at end 132. With this arrangement the greatest number
of electrons from the cathode will pass through the open—
its external end for attaching more waveguides and has
ing of the drift tube and not be intercepted by the posi
a matching plug 86 to match the circuit.
tive potential thereon because the larger diameter at
Directly opposite the waveguide and on the waveguide
the exit of the drift tube accommodates the defocusing
center. line is disposed the tuning assembly 17. A rec
tangular port 88 is machined in body 16 to accommodate 30 electron beam. Port 67 in plate 66 is made larger than
a rectangular ceramic tuning slug 90. I Port 88 com
the drift tube bore for the same reason.
The electrons pass through the cavity 20 and the in
teraction gap where they are in?uenced by a velocity
modulating force which accelerates certain electrons and
ceramic tuning slug 90 is brazed to the end of a control 35 decelerates other electrons. The electrons after passing
across the interaction gap are repelled by the repeller
rod 96 which slides through the guide plug 94. The
124 back across the gap. During‘ this action the fast
other end of the control vrod has a thick ?ange 98 and
electrons tend to catch up with the slow electrons so
a spring 100‘ is disposed between the ?ange 98 and guide
that the electrons in recrossing the gap are in bunches
plug 94,.urging the tuning slug 90‘ out of the body' 16.
producing the power output of the klystron. This power
A vacuum seal is made with the aid of a metal bellows
is directly proportional to the compactness of the bunches.
102 between ?ange 98 and guide plug 94. A tubular
Since electrons traveling on the tube axis travel a shorter
support 104 is held in place by screws 105 bearing against
distance than the electrons removed from the tube axis, '
plug 94. The support 104 keeps the rod 96 in line and
the electrons on the axis will tend to be out of phase
supports a ball bearing 106 in the external end. A tun
ing shaft 108 is pressed into the inner bearing race. A 45 with the outer electrons so that compact bunches are not
municates with the resonant cavity 20‘. A counterbore
.92 is machined coaxially with the port 88 and a tubular
guide plug 94 is welded in the counterbore 92. The
screw thread 110 on the inner end of shaft 108 engages
produced.
mating threads on nut 112 which is pressed tightly in an
axial well 114 bored in the outer end of the control rod
96. As the shaft 108 is rotated, the nut 112 moves axially
According to this invention ‘all the electrons are re
turned in phase across the interaction gap by a contoured
repeller surface 126, which has a novel con?guration.
The preferred con?guration on repeller surface 126
on the threads 110', urging the control rod 96 and ceramic 50
is of a hollow conical frustum with its small ?at base 135
tuning plug 90 with it.
recessed in the repeller 124. A sharp center point 134
The repeller header assembly 14 has 'an annular disk
protrudes coaxially from the smaller base. The length
An’exhaust tubulation 118 pro
of point 134 is made shorter than the depth of the
trudes through the header 116. Since the tubulation
118 has a thick wall, it is not brazed directly to the 55 frustum. The surface 126 is symmetrical on the tube
axis. The center point 134 de?ects radially the electrons
header as the header will have temperature changes which
traveling on the klystron axis, allowing hte electrons on
will cause excessive thermal stresses. A conical metal
the outer edge of the beam time to catch up and bunch
sealing ring 120 ‘is brazed on its periphery to the inside
with them. In other words, the electrons on the klystron
surface of the header 116. The tubulation 118 is welded
to an upturned internal ?ange on the sealing ring 1201. 60 axis are caused to disperse radially, and the conical sur
face of the repeller surface 126 then helps to focus the
Also, on the inner surface of header 116 is brazed a
re?ected electron beam radially so that the electrons pass
tubular repeller support v122 by its outward turned ?ange.
across the interaction gap in phase with each other.
The support 122 makes electrical contact with the ring
The space between port 67 and the adjacent end of
120. On the other end of the support 122 ‘is brazed
ceramic header 116.
a repeller 124 with a novel contoured repeller surface 65 the drift tube 62 is known as the interaction gap. Since
the gap spacing is small in comparison to the port size,
126 which will be described more fully hereinafter. The
the electrons which are on the axis would not be a?ected
tubulation 118 is protected by a ?anged tube 128 brazed
by the cavity ?eld. Therefore, grids 137 and 136 are
in the hole of the header 128. A contact cap 130 is
placed in the ports. The grids each have sixteen molyb
brazed on the tube 128. The cap and tube 128 provide
70 denum radial vanes suspended from the port periphery
the external terminal for ‘the repeller 124. A sealing
ring 30' similar to sealing ring 30 is brazed to the ceramic
repeller header 116 in the same manner aslsealing ring 30
is brazed to the ceramic cathode header 22.
It is observed that the cathode header assembly 12 75
leaving the center open. The radial type grids with the
center opening were used because this arrangement of
fered the least interference with the electron ?ow. Six
teen vanes were used to keep the space between the
vanes to less than one electron wavelength and to provide
3,043,985
5
adequate electrostatic coupling between the gap. ‘An
electron wavelength is de?ned as the distance an electron
Will travel at the operating voltage during one cycle of
the operating frequency. Grid 137 is disposed in port
67, and grid 136 similar to grid 137 but of a smaller
diameter is disposed in the adjacent end of drift tube 62
with the radial vanes aligned with grid 137 vanes. With
this arrangement grid 136 does not add interference to
%
end thereof, a ceramic’ tuning slug disposed in said reso
nant cavity formed by said ?rst means forming said in
teraction Igap surrounded by said resonant cavity, mecha
nical means provided for withdrawing and inserting said
ceramic tuning slug within said resonant cavity and for
tuning said resonant cavity from the exterior of said,
tubular body, and a vacuum-tight ceramic window in
said resonant cavity. for radiating high frequency electro
magnetic power from said tubular body.
3. A re?ex klystron comprising a tubular conductive
Referring to FIGURE 2, there is shown the novel 10
body, a ?rst ceramic header disk hermetically closing one
ceramic tuning slug 90‘ disposed Within cavity 20. This
end of said tubular body, a plurality of contact prongs
view shows the inner end of the ceramic slug 90 with a
extending through said ?rst header disk, a gridless elec
semi-cylindrical concave surface 138. The slug 90‘ is
tron gun mounted on said ?rst header disk connected to
positioned by shaft 108 to its inmost position towards
said contact prongs, said electron gun being disposed co
the klystron axis, and the drift tube 62, shown in cross
axially within said tubular body for emitting a beam of
section, is disposed Within the concave surface 138. The
electrons along said tubular body axis, a second ceramic
ceramic slug 90 has a rectangular cross-section and is
header disk heremetically closing the other end of said
made to ?ll the tuning cavity 20 as much as practical
tubular body, a repeller electrode mounted on said sec
when fully inserted. The lower frequencies are obtained
ond ceramic header disk coaxially within-said tubular
with the ceramic slug fully inserted. The rectangular
body, said body including means forming an interaction
slug 90 has been found to give a more uniform tuning
the electron beam.
,
gap coaxial within said body and surrounded by a reson
ant cavity, said' repeller electrode having a contoured
repeller surface comprising a hollow conical frustum
The control rod 96 is made round, and the inner end
of the rod stops on the body 16 (FIGURE 1). This 25 shapedisposed with its smaller ?at base recessed into said
rate with each turn of the shaft 108 than any other
simple geometric shape.
cm
prevents the ceramic slug from ‘bearing on the drift tube
62. Upon retraction of the slug 90 the outer end of rod
96 rests against bearing 106, which is the outer stop.
Thus, a re?ex klystron having more efficiency, a higher
output power and broadband tuning is provided. The
ef?ciency and output power is increased by combining a
gridless electron gun, an elongated step-bored drift tube
anode, and a contoured repeller face. The broadband
tuning is obtained by a ceramic tuning slug which is mov
able in and out of the resonant cavity.
We claim:
'
l. A re?ex klyston comprising an electron gun, a re
repeller electrode coaxial with said tubular body, and a
sharp point coaxial with said tubular body and protrud
ing from said smaller base towards said electron gun,
said resonant cavity having a drift tube section one end
of which forms a boundary of said interaction gap and
the other end of said drift-tube section being disposed
adjacent said gridless electron gun and forming the anode
of said gun, said drift tube section having a smaller inner
diameter at said other end thereof, *a ceramic tuning slug
disposed in said resonant cavity, mechanical means pro
vided for withdrawing and inserting said ceramic tuning
slug within said resonant cavity and for tuning said
resonant cavity from the exterior of said tubular body,
peller electrode, body means forming an interaction gap
and a vacuum-tight ceramic window in said resonant cavity
surrounded by a resonant cavity disposed between said
electron gun and repeller electrode and coaxial therewith, 40 for radiating high frequency electromagnetic power from
said tubular body.
said resonant cavity having a drift tube section one end
4. A re?ex klystron comprising a gridless electron gun,
of which forms a boundary of said interaction gap, a
ceramic tuning slug having a rectangular cross-section
disposed within said resonant cavity and insertable
a repeller electrode, and body means forming an inter- ,
through a port formed in said body means, said ceramic
tuning slug having a concave semi-cylindrical surface on
its end adjacent said drift tube, mechanical means in
cluding a metallic bellows covering said port formed in
tween said gridless gun and said repeller, said gridless
electron gun comprising a heating ?lament disposed
within a cylindrical heat shield, said heat shield support
said body means provided for withdrawing and inserting
said ceramic tuning slug within said resonant cavity and
sealing said port and tuning said resonant cavity from
the exterior of said re?ex klystron tube.
electrode surrounding said heat shield and spaced there
from, said focusing electrode extending beyond said
2. A re?ex klystron tube comprising a tubular con
ductive body having a cathode header disposed at one
end and a repeller header disposed on the other end
forming a vacuum envelope, a gridless electron gun dis
posed on said cathode header and within said body for
emitting a beam of electrons along said tubular. body
axis, said body including means forming an interaction
action gap surrounded by a resonant cavity ‘disposed be
ing a concave cathode at one end, a cylindrical focusing
cathode from said ?lament, a ?rst flat ring having an
inner diameter equal to said cathode diameter disposed
within said focusing electrode adjacent said cathode, and
a second ?at ring having an inner diameter equal to said
cathode diameter disposed on the end of said focusing
electrode spaced from said ?rst ?at ring and said cathode.
5. A re?ex klystron comprising a tubular conductive
body, a ?rst ceramic cathode header disk heremetically
closing one end of said tubular body, eight contact prongs
60 evenly spaced in a circle coaxial with said tubular body
gap coaxial Within said body and surrounded by a reso
and extending through said ?rst header disk, an indexing
nant cavity, a repeller electrode disposed on said repeller
prong disposed coaxial with an external of said tubular
header within and coaxial with said tubular body on the
body and disposed on said ?rst header disk, a gridless
opposite side of said interaction Igap from said electron
electron gun mounted on said ?rst header disk and con
gun, said repeller electrode having a contoured repeller
surface comprising a hollow conical frustum shape 65 nected to said contact prongs, said velectron gun disposed
coaxial within said tubular body for emitting a beam of
recessed into said repeller electrode and disposed with
electrons along said tubular body axis, ‘a second ceramic
its smaller ?at base recessed into said repeller electrode
header disk heremetically closing the other end of said
coaxial with said tubular ‘body, and a sharp point coaxial
with said tubular body and protruding from said smaller
tubular body, a repeller electrode mounted on said sec
base towards said electron gun, said resonant cavity hav 70 ond ceramic header disk coaxially within said tubular
body, said body including means forming an interaction
ing a drift tube section one end of which forms a bound
gap coaxial within said body and surrounded by a reson
ary of said interaction gap and the other end of said drift
ant cavity, said repeller electrode having a contoured
tube section being disposed adjacent said gridless elec
repeller surface comprising a hollow conical frustum shape
tron gun and forming the anode of said gun, said drift
tube section having a smaller inner diameter at said other 75 disposed with its smaller [?at base recessed into said re
3,043,985
.
7
8 .
,
peller. electrode coaxial with said tubular body and a
sharp point coaxial with said tubular body and protrud
ing from said smaller base towards said electron gun, said
resonant cavity having a drift tube sectionone end of
which forms a boundary of said interaction gap andthe
section and having a semi-cylindrical concave surface on
other end-of said drift tube section being disposed adja- .
cent said gridless electron gun and forming the ‘anode of
said gun,’ said drift tube section having a smaller inner
said gun including cathode means for producing ‘a solid
beam of electrons, body means forming an interaction gap
its end facing the tube axis for ?tting around said drift
tube section Whensaid ceramic tuning slug is fully in
serted Within said cavity.
7. A re?ex klystron tube comprising an electron gun,
surrounded by a resonant cavity, and a repeller electrode
disposed in that order and coaxial with each other, said
diameter at ‘said other end thereof, a ceramic tuning slug
disposed in said resonant cavity, mechanical means pro 10 repeller electrode having a contoured repeller surface
comprising a hollow conical frustum shape with its smaller
vided for withdrawing and inserting said ceramic tuning
base recessed into and coaxial with said repeller electrode,
slug within said resonant cavity and for tuning said reso
and a sharp point protruding from said smaller base to
nant cavity from the exterior of said tubular body, and
Ward said electron gun and disposed coaxial therewith.
a vacuum-tight ceramic window in said resonant cavity
for radiating high frequency electromagnetic power ?om 15
said tubular body.
‘
6. .A re?ex klystron as set forth in claim 5 wherein
said gridless electron gun comprises a heating ?lament
disposed within a cylindrical heat shield, said heat shield
supporting a concave cathode at one end, a cylindrical 20
focusing electrode surrounding said heat shield and spaced
therefrom, said focusing electrode extending beyond said
cathode from said filament, a ?rst ?at ring having an
vinner diameter equal to said cathode diameter disposed
within said focusing electrode adjacent said cathode, and 25
_'a second ?at ring having an inner diameter equal to said
cathode diameter disposed on the end of said focusing
electrode spaced from said ?rst ?at ring and said cathode,
and said ceramic tuning slug having a rectangular cross
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,411,913
2,466,062
Pierce et a1. ___________ .._ Dec. 3, 1946
Striatton __‘____________ .._ Apr. 5, 1949
2,468,152
2,570,289
Woodyard ___.., _______ __ Apr. 26, 1949
Touraton et a1 __________ __ Oct. 9, 1951
2,581,408
Hamil-ton __________ _'___'__- Jan. 8, 1952
2,777,969
2,861,213
Svensson _____________ __ Jan. 15, 1957
Dalman _____________ __ Nov. 18, 1958
2,878,415
Gormley et a1 _________ __ Mar. 17, 1959
739,716
Great Britain _________ __ Nov. 2, 1955
FOREIGN PATENTS
m4
UNITED STATES PATENT OFFICE
‘CERTIFICATE OF CORRECTION
Patent No. 3,043,985
July 1OI 1962
Rowland W. Haegele et a1.
It is hereby certified that error appears in the above numbered pat
ent requiring correction and that the said Letters Patent should read as
corrected below.
.
Column 4,
line 57,
for "hte" read -- the ——;
column 6,
11ne 62, for "an" read --— and -—; line 68, for "heremetically"
read
—-— hermetically
-—.
Signed and sealed this 30th day of October 1962.
A(SEA
_ L)
ERNEST w. swmsn
Atteeting Of?eer
_
DAVID L- LADD
.
‘
Commissioner of Patents
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