Carbon and Beryllium Targets at PSI
Carbon and Beryllium Targets at PSI
G. Heidenreich
G. Heidenreich
Paul Scherrer Institut
Paul Scherrer
Institut
Villigen
PSI, Switzerland
Villigen PSI, Switzerland
Abstract. The Paul Scherrer Institut (PSI) operates a cyclotron facility for the production of a high intensity proton
beam at an The
energy
590 MeV.
The majority
of the beam
is delivered
thethe
twoproduction
target stations
andintensity
E, mounted
in
Abstract.
Paulof Scherrer
Institut
(PSI) operates
a cyclotron
facilitytofor
of a M
high
proton
series,attoangenerate
and
beams
particle to
physics
andtarget
muon-spin-resonance
beam
energy intense
of 590 pion
MeV.
Themuon
majority
of for
theresearch
beam is indelivered
the two
stations M and E,applications.
mounted in
Both targets
consistintense
of rotating
wheels
of polycrystalline
graphite
cooled physics
by thermal
About 40% of
the proton
series,
to generate
pion and
muon
beams for research
in particle
and radiation.
muon-spin-resonance
applications.
beamtargets
is lost consist
at the target-E
station;
the of
remainder
of the beam
is transported
to the spallation
or to
Both
of rotating
wheels
polycrystalline
graphite
cooled by thermal
radiation.neutron
About source
40% ofSINQ
the proton
a beam
dump.
Since
the upgrade
cyclotron,
the beam
targetisfacilities
haveto had
to handle neutron
significantly
beam
is lost
at the
target-E
station; to
thethe
remainder
of the
transported
the spallation
sourcehigher
SINQbeam
or to
both target
were completely
rebuilt the
(M target
in 1985
and E in
1990)
mA. An overview
the
acurrent;
beam dump.
Sincestations
the upgrade
to the cyclotron,
facilities
have
hadtotohandle
handle2 significantly
higher ofbeam
meson production
willwere
be presented,
on 1985
designand
andE operational
of 2themA.
targets
at PSI.
current;
both targettargets
stations
completelyconcentrating
rebuilt (M in
in 1990) tolimits
handle
An used
overview
of the
meson production targets will be presented, concentrating on design and operational limits of the targets used at PSI.
INTRODUCTION
The 11 MW
MW proton
proton beam
beam from
from the
the 590
590 MeV
The
MeV
cyclotron is
is delivered
delivered to
to two
two meson
meson production
production targets,
cyclotron
targets,
"M" and
and "E",
"E", mounted
mounted in
in series,
"M"
series, which
which generate
generate
intense pion
pion and
and muon
muon beams
beams for
research in
intense
for research
in particle
particle
physics and
and for
for muon
muon spin-resonance
spin-resonance applications
physics
applications
(µSR). These
These targets
targets consist
consist of
(jiSR).
of rotating
rotating wheels
wheels of
of
polycrystalline
graphite,
cooled
by
thermal
polycrystalline graphite, cooled by thermal radiation.
radiation.
Some parameters
parameters for
for the
the targets
targets are
are given
given in
in table
table 1.
Some
1.
Target-M
feeds
two
meson
beam-lines,
π-M1
high
Target-M feeds two meson beam-lines, 7C-M1 aa high
resolution pion
pion beam
beam and
and 7C-M3,
π-M3, which
which is
resolution
is dedicated
dedicated to
to
µSR
applications.
The
target-E
complex
provides
jiSR applications. The target-E complex provides five
five
high intensity
intensity meson
meson beam-lines;
beam-lines; π-E1,
π-E3 and
high
7C-E1,7C-E3
and π-E5
7C-E5
for
pions;
µ-E1
and
µ-E4
for
muons.
After
target E,
E,
for pions; |i-El and |i-E4 for muons. After target
the
remaining
proton
beam
(60%
of
typically
1.8
mA)
the remaining proton beam (60% of typically 1.8 mA)
is either
either delivered
delivered to
to the
the spallation
spallation neutron
neutron source
is
source
SINQ
or
defocused
and
stopped
in
a
high
power beam
SINQ or defocused and stopped in a high power
beam
dump. Before
Before the
the meson
meson production
production targets,
targets, there
there is
dump.
is an
an
electrostatic
splitter,
which
allows
between
100
electrostatic splitter, which allows between 100 nA
nA
and 20
20 |iA
µA to
to be
be split
split from
from the
the main
main beam
beam for
use in
in
and
for use
the
NA-Hall.
This
low
intensity
proton
beam
is
used
the NA-Hall. This low intensity proton beam is used
by PIE
PIF (proton
(proton irradiation
irradiation facility)
facility) and
by
and Gantry
Gantry (proton
(proton
therapy
facility).
A
degrader
is
available
therapy facility). A degrader is available to
to reduce
reduce the
the
energy of
of the
the proton
proton beam
beam to
to aa few
few hundred
hundred MeV
MeV and
energy
and
an intensity
intensity of
of aa few
nA. Two
Two new
new projects
projects are
an
few nA.
are
planned
in
the
NA
Hall:
planned in the NA - Hall:
(i) The
The project
project PROSCAN.
PROSCAN. This
(i)
This is
is aa dedicated
dedicated
250
MeV
cyclotron
for
proton
therapy,
250 MeV cyclotron for proton therapy, feeding
feeding two
two
treatment rooms
rooms and
and one
one experimental
treatment
experimental area.
area,
(ii) The
The construction
construction of
of an
ultra cold
(ii)
an ultra
cold neutron
neutron source
source
(UCN),
based
on
the
spallation
process.
(UCN), based on the spallation process. With
With the
the help
help
of aa fast
fast kicker
kicker the
the whole
whole beam
beam (2
mA) will
will be
be
of
(2 mA)
directed
onto
the
UCN
spallation
target
for
a
few
directed onto the UCN spallation target for a few
seconds every
every 10
This
seconds
10 minutes.
minutes.
This should
should produce
produce aa UCN
UCN
3
density
of
4000/cm
3 (orders of magnitude higher than
density of 4000/cm (orders of magnitude higher than
any other UCN source in the world).
any other UCN source in the world).
FIGURE 1. Layout of the PSI accelerator facility. Two new
FIGURE 1. Layout of the PSI accelerator facility. Two new
projects are planned in the NA-Hall: the project PROSCAN,
projects are planned in the NA-Hall: the project PROSCAN,
a dedicated 250 MeV Cyclotron for cancer therapy and the
a dedicated 250 MeV Cyclotron for cancer therapy and the
Ultra Cold Neutron Source.
Ultra Cold Neutron Source.
CP642, High Intensity and High Brightness Hadron Beams: 20th ICFA Advanced Beam Dynamics Workshop on
High Intensity and High Brightness Hadron Beams, edited by W. Chou, Y. Mori, D. Neuffer, and J.-F. Ostiguy
© 2002 American Institute of Physics 0-7354-0097-0/02/$ 19.00
122
crane.
There
no
need
for
local
mechanical
workon
on
crane.
crane.There
Thereisis
isno
noneed
needfor
forlocal
localmechanical
mechanicalwork
work
on
the
highly
activated
components.
The
rotating
carbon
the
thehighly
highlyactivated
activatedcomponents.
components.The
Therotating
rotatingcarbon
carbon
target,
beam
monitors,
beam
collimators
andthe
thebeam
beam
target,
target,beam
beammonitors,
monitors,beam
beamcollimators
collimatorsand
and
the
beam
dump
elements
can
be
removed
into aaa remotely
remotely
dump
dump elements
elements can
can be
be removed
removed into
into
remotely
controlled
shielded
flask
and
transported
byaaacrane
cranetoto
to
controlledshielded
shieldedflask
flaskand
andtransported
transportedby
by
crane
controlled
the
hot
cell
for
maintenance.
thehot
hotcell
cellfor
formaintenance.
maintenance.
the
ii)
The
connections
between
beam
pipes and
and
ii) The
The connections
connections between
between beam
beam pipes
pipes
and
ii)
vacuum
chambers
are
made
by
means
ofinflatable
inflatableallallvacuumchambers
chambersare
aremade
madeby
bymeans
meansofof
inflatable
allvacuum
metal
seals
which
do
not
require
anyclamping.
clamping.
metalseals
sealswhich
whichdo
donot
notrequire
requireany
any
clamping.
metal
TABLE
1.1.Some
Some
Parameters
For
The
Targets
TABLE
TABLE1.
SomeParameters
ParametersFor
ForThe
TheTargets
Targets
M
Meson
Production
Target
Meson
M
EEE
MesonProduction
ProductionTarget
Target
M
Mean
Diameter
(mm)
320
450
Mean
320
450
MeanDiameter
Diameter(mm)
(mm)
320
450
5.2
Target
Length
(mm)
60
Target
5.2
60
TargetLength
Length(mm)
(mm)
5.2
60
Target
(mm)
20
TargetWidth
Width(mm)
(mm) 3
20
Target
Width
20
666
Graphite
Density
(g/cm
1.8
1.8
GraphiteDensity
Density(g/cm
(g/cm3))3)
1.8
1.8
Graphite
1.8
1.8
Proton
Beam
Losses
(%)
1.6
18
ProtonBeam
BeamLosses
Losses(%)
(%)
1.6
18
Proton
1.6
18
2.4
Power
Deposition
(KW/mA)
30
PowerDeposition
Deposition(KW/mA)
(KW/mA)
2.4
30
Power
2.4
30
Irradiation
Damage
Rate
(dpa/Ah)
0.11
0.1
IrradiationDamage
DamageRate
Rate(dpa/Ah)
(dpa/Ah)
0.11
0.1
Irradiation
0.11
0.1
Operating
Temperature
(K)
1100
1700
OperatingTemperature
Temperature(K)
(K)
1100
1700
Operating
1100
1700
Rotational
Speed
(Turns/s)
RotationalSpeed
Speed(Turns/s)
(Turns/s)
Rotational
111
111
iii)
All
the
power-,
coolingandsignal
signalconnections
connections
iii)All
Allthe
thepower-,
power-,coolingcooling-and
and
signal
connections
iii)
are
brought
through
the local
local shielding
arebrought
broughtthrough
through the
shieldingtotoaa working
working
are
platform
2.5mmabove
abovethe
theproton
protonbeam
beamaxis,
axis,where
wherethe
the
platform2.5
axis,
where
the
platform
dose
rate
(with the
the beam
beam off)
off)
allow
doserate
rate(with
off)isislow
lowenough
enough totoallow
allow
dose
hands-on
maintenance.
hands-onmaintenance.
maintenance.
hands-on
STATION
M
TARGETSTATION
STATIONM
M
TARGET
Target-M
asasaaahorizontal
horizontal
insert.
The
Target-Misis designed
designedas
horizontal insert.
insert. The
The
rotation
made
using
long
drive
shaft
rotationofofthe
thetarget
targetisismade
madeusing
usingaaalong
longdrive
driveshaft
shaft
equipped
ball
bearings,
the
balls
and
equippedwith
withaapair
pairofofball
ballbearings,
bearings,the
theballs
ballsand
and
rings
lubrication
and
to
ringsare
aresilver
silvercoated
coatedtotoachieve
achievelubrication
lubrication and
and to
to
prevent
ininvacuum.
vacuum.
The
drive-motor
preventadhesive
adhesivewear
wearin
vacuum.The
Thedrive-motor
drive-motorisisis
mounted
with
the
torque
to
the
mountedoutside
outsidethe
thevacuum
vacuumwith
with the
thetorque
torqueto
to the
the
drive
permanent-magnet
clutch.
driveshaft
shafttransmitted
transmittedby
byaapermanent-magnet
permanent-magnetclutch.
clutch.
Thepresent
presenttarget-M
target-Munit
unithas
hasoperated
operatedfor
formore
morethan
than
The
has
operated
for
more
than
50’000hours
hourswithout
withoutfailure
failuresince
sinceitititwas
wasinstalled
installedin
in
50'000
since
was
installed
in
50’000
1991.The
Thegraphite
graphiteofofthe
thetarget
targethas
hasbeen
been irradiated
irradiated
1991.
with total
total integrated
integrated beam
beam current
current of
of 44
44Ah,
Ah, which
which
with
current
of
44
Ah,
which
correspondstotoaaradiation
radiation damage
damagelevel
level of
ofabout
about 444
corresponds
damage
level
of
about
dpa.
dpa.
WORKINGPLATFORM
PLATFORM
WORKING
BEAM
BEAM
DUMP
DUMP
TARGETEE
E
TARGET
TARGET
toto S
SI NI N
QQ
FIGURE3.3.
3.Design
Designofofthe
channelbetween
betweenTarget
Target
FIGURE
FIGURE
Design
theproton
protonchannel
TargetEEE
andthe
thebeam
beamdump.
and
and
the
beam
dump.
The target
target consists
cone ofof
The
The
target
consists ofof aa rotating
rotating cone
of
polycrystallinegraphite,
bythermal
thermal radiation.
radiation.
polycrystalline
polycrystalline
graphite, cooled
cooled by
radiation.
Thecone
coneisis
isattached
attachedtotothe
thewheel
wheelhub
hubby
bysix
sixspokes.
spokes.
The
The
cone
by
This
design
allows
dimensional
changes,
such
This
This design
design allows
allows dimensional
dimensional changes,
changes, such
such asas
as
thermal
expansion
during
heating,
to
be
taken
but
thermal
expansion
during
heating,
to
be
taken
up,
thermal expansion during heating, to be taken up,
up,but
but
constrains the
the irradiation-induced
irradiation-induced anisotropic
anisotropic
constrains
constrains
the
irradiation-induced
anisotropic
shrinkageof
ofthe
thepolycrystalline
polycrystallinegraphite,
graphite,which
which
causes
shrinkage
shrinkage
of
the
polycrystalline
graphite,
whichcauses
causes
deformationof
ofthe
theshape
shapeand
and
henceleads
leads
radial
deformation
deformation
of
the
shape
andhence
hence
leadstoto
toaaaradial
radial
wobble. The
The radial
radial displacement
displacement amplitude
amplitude
must
be
wobble.
wobble.
The
radial
displacement
amplitude must
must be
be
less
then
2
mm
during
operation
of
the
target.
Figure
less
lessthen
then22mm
mmduring
duringoperation
operationofofthe
thetarget.
target.Figure
Figure555
showsthe
themeasured
measuredradial
radialdisplacement
displacementrate
rate
[mm/Ah]
shows
shows
the
measured
radial
displacement
rate[mm/Ah]
[mm/Ah]
for
the
targets
made
from
the
graphite
grades
R6300P
for
the
targets
made
from
the
graphite
grades
for the targets made from the graphite gradesR6300P
R6300P
and
R6400P
[1].
Since
1997
the
targets
were
made
and
R6400P
[1].
Since
1997
the
targets
were
and R6400P [1]. Since 1997 the targets were made
made
from R6400P,
R6400P, which
which isis
is aaa more
more isotropic
isotropic
form
from
from
R6400P,
which
more
isorropic form
form ofof
of
graphite. This
This has
has resulted
resulted inin
significant
graphite.
graphite.
This
has
resulted
in aaa significant
significant
improvementof
ofthe
thelifetime,
lifetime,which
which
presently
reaches
improvement
improvement
of
the
lifetime,
whichpresently
presentlyreaches
reaches
10
Ah
(one
operational
year).
The
target
is
driven
by
10
10Ah
Ah(one
(oneoperational
operationalyear).
year).The
Thetarget
targetisisdriven
drivenby
byaaa
long
vertically
mounted
drive
shaft,
so
that
the
electric
long
vertically
mounted
drive
shaft,
so
that
the
electric
long vertically mounted drive shaft, so that the electric
motorisis
ismounted
mountedinin
inaaalow
lowradiation
radiationfield
field
region.
The
motor
motor
mounted
low
radiation
fieldregion.
region.The
The
bearings
contain
steel
balls;
the
rings
and
the
balls
bearings
contain
steel
balls;
the
rings
and
the
balls
are
bearings contain steel balls; the rings and the balls are
are
silver coated
coated toto
to act
act as
as lubricant.
lubricant. The
The lifetime
lifetime
the
silver
silver
coated
act
as
lubricant.
The
lifetime ofof
ofthe
the
bearingsisis
isabout
about3000
3000hours
hourspresently
presently
and
causes
up
bearings
bearings
about
3000
hours
presentlyand
andcauses
causesup
up
to
three
replacements
of
the
target
insert
per
to
to three
three replacements
replacements ofof the
the target
target insert
insert per
per
operational year.
year. AA longer
longer lifetime
lifetime isis expected
by
operational
operational
year.
A longer
lifetime is expected
expected by
by
FIGURE 2.2. Picture
Picture of
the target-M
target-M unit.
unit. The
The arrow
arrow
FIGURE
Picture
ofof the
the
target-M
unit.
The
arrow
indicatesthe
thedirection
directionof
theproton
protonbeam.
beam.
indicates
indicates
the
direction
ofofthe
the
proton
beam.
TARGETSTATION
STATIONE
TARGET
STATION
EE
theyear
year1990
1990aaanew
newmechanical
mechanicaldesign
designof
the
In
year
InInthe
the
1990
new
mechanical
design
ofofthe
the
target
station
E
and
of
the
beam
dump
was
installed.
target station
target
station E
E and
and of
of the
the beam
beam dump
dump was
was installed.
installed.
Themain
mainfeatures
featuresare:
are:
The
The
main
features
are:
All the
the beam
beam line
line elements
elements and
and their
their local
local
i)
beam
i)i) All
All
the
line
elements
and
their
local
shieldings
are
mounted
on
support
stands,
which
are
shieldings
shieldings are
are mounted
mounted on
on support
support stands,
stands, which
which are
are
precisely
positioned
on
ground
plates,
allowing
a
selfprecisely positioned
precisely
positioned on
on ground
ground plates,
plates, allowing
allowing aa selfselfcentering installation
installation of
the elements
elements without
without any
any
centering
centering
installation
ofof the
the
elements
without
any
fastenings. All
All elements
elements can
can thus
thus bebe installed
installed and
and
fastenings.
fastenings. All elements can thus be installed and
removedexclusively
exclusively inthe
the verticaldirection
direction withthe
the
removed
removed
exclusively in
in the vertical
vertical direction with
with the
123
for theberyllium
berylliumand
andcarbon
carbontargets
targetsasasaa afunction
functionofof
for
for the
the beryllium
beryllium and
and carbon
carbon targets
targets as
as a function
function of
of
I/D-e*,
which
is
the
proton
current
I(mA),
dividedbyby
I/D⋅ε*,
which
isisthe
the
proton
current
I(mA),
divided
I/D⋅ε*, which
whichis
theproton
proton current
currentI(mA),
I(mA),divided
dividedby
by
the targetdiameter
diameterD(m)
D(m)multiplied
multipliedbybythe
theeffective
effective
the
D(m)
the target
target diameter
diameter
D(m) multiplied
multiplied by
by the
theeffective
effective
*8*
** of the radiating surfaces. The current
emissivity
emissivity
of
the
radiating
surfaces.
The
current
emissivity εεε of
of the
the radiating
radiating surfaces.
surfaces. The
The current
current
design for
for the
the graphite
graphitetargets
targetshave
haveaaaadiameter
diameterof
design
the
graphite
targets
have
diameter
of
design
for
the
graphite
targets
have
diameter
ofof
D=0.45
m
and
an
effective
emissivity
of
e*=0.75,
D=0.45
m
and
an
effective
emissivity
of
ε*=0.75,
D=0.45 m and
and an
an effective
effective emissivity
emissivity of
of ε*=0.75,
ε*=0.75,
which gives
gives acceptable
acceptable operational
operationalparameters
parametersfor
for
which
gives
acceptable
operational
parameters
for
which
gives
acceptable
operational
parameters
for
proton
currents
up
to
3
mA
(I/D-e*=8.9).
In
the
case
proton
currents
up
to
3
mA
(I/D⋅ε*=8.9).
In
the
case
of
proton currents
currents up
up to
to 33 mA
mA (I/D⋅ε*=8.9).
(I/D⋅ε*=8.9). In
In the
the case
case of
ofof
beryllium
target,
a
diameter
ten
times
larger
would
aaaberyllium
target,
a
diameter
ten
times
larger
would
target,
a
diameter
ten
times
larger
would
beryllium target, a diameter ten times larger would
benecessary.
necessary,(e.g.
(e.g.for
for3333mA
mA4.5
4.5m
diameter).In
the
be
necessary.
(e.g.
for
mA
4.5
m
diameter).
In
the
be
necessary.
(e.g.
for
mA
4.5
mmdiameter).
diameter).
InInthe
the
earlydays
daysof
ofoperation,
operation,beryllium
berylliumtargets
targetswere
wereused
used
early
of
operation,
beryllium
targets
were
used
early
days
of
operation,
beryllium
targets
were
used
withbeam
beamcurrents
currentsup
upto
to150
150µA.
|iA.The
Thetargets
targetswith
withaaa a
with
with
beam
currents
up
to
150
µA.
The
targets
with
with
beam
currents
up
to
150
µA.
The
targets
with
diameter
diameter of
of0.19
0.19m
mand
andan
aneffective
effectiveemissivity
emissivityof
diameter
of
0.19
m
and
an
effective
emissivity
of
diameter
of
0.19
m
and
an
effective
emissivity
ofof
ε*=0.6
to
e*=0.6failed
failedat
atoperating
operatingcurrents
currentsof
120µA
|iAdue
due
ε*=0.6
failed
at
operating
currents
of
120
µA
due
to
ε*=0.6
failed
at
operating
currents
ofof120
120
µA
due
toto
cracks
cracks of
of the
the target
target cone
cone (I/D⋅ε*=1.05);
(I/D-e*=1.05);with
withaaa a
cracks
of
the
target
cone
(I/D⋅ε*=1.05);
with
cracks
of
the
target
cone
(I/D⋅ε*=1.05);
with
diameter
up
to
diameterof
of0.28
0.28m
mthey
theyoperated
operatedsuccessfully
successfullyatat
diameter
of
0.28
m
they
operated
successfully
up
to
diameter
of
0.28
m
they
operated
successfully
atat
upup
toto
150
µA
(I/D⋅ε*=0.89).
150µA
jiA(I/D⋅ε*=0.89).
(I/D-e*=0.89).
150
150
µA
(I/D⋅ε*=0.89).
using
commercially
available bearings
bearings with silicon
silicon
using
commercially
using
using commercially
commercially available
available bearings with
with silicon
nitride
balls
[2];
these
will
be
tried
out
this
year.
nitride
balls
[2];
nitride
nitrideballs
balls[2];
[2];these
thesewill
willbe
betried
triedout
outthis
thisyear.
year.
10000
FIGURE
4.4. Picture
Picture
of
the
Target-E
unit.
FIGURE 4.
Picture of
of the
the Target-E
Target-E unit.
unit. The
arrow
The
arrow
FIGURE
Picture
of
the
Target-E
unit.
The arrow
indicates
the
direction
of
the
proton
beam.
indicatesthe
thedirection
directionof
theproton
protonbeam.
beam.
indicates
ofofthe
the
proton
beam.
^1
Z
<£
0.7
0.7
0.7
u.r
1
0.6
0.6
1 0.6
E, n0.5
c
0.5
0.5
* 0-5
< 0.4
0.4
0.4
3> 0.4
R6300P
R6300P
R6300P
HJ"R63
°op
R6400P
∆∆
∆
R6400P
R6400P
• •R6400P
ro
£
~
0
0.2
0.2
0.2
Hiu 0.2
TO
1
0.3
0.3
0.3
0.3
I
0.1
0.1
0.1
& °'1
Q
0
00
\
0.5
1
1.5
1.5
0.5
1.5 1.5
1.5 1.8
1.8
0.5
11
1.5
1.8
0.5
1
1.5
1.5
1.8
Mean
Proton
Current
[mA]
MeanProton
ProtonCurrent
Current[mA]
[mA]
Mean
Proton
Current
Mean
[mA]
FIGURE
Variation
FIGURE6.
Variationof
ofthe
thecritical
criticaloperational
operationalparameters
parameters
FIGURE
6.6.
of
critical
operational
parameters
FIGURE
6. Variation
Variation
ofthe
the
critical
operational
parameters
(the
temperature,
the
safety
factor
and
(the temperature,
temperature, the
the safety
safety factor
factor and
andthe
theevaporation
evaporationrate)
rate)
(the
the
evaporation
rate)
(the
temperature,
the
safety
factor
and
the
evaporation
rate)
for
forthe
theberyllium
berylliumand
andcarbon
carbontargets
targetsas
asaaafunction
functionof
ofI/D⋅ε*,
I/D⋅ε*,
for
the
beryllium
and
carbon
targets
as
function
of
I/D⋅ε*,
for theisberyllium
andcurrent
carbonI(mA),
targets divided
as a function
oftarget
I/D-e*,
which
the
proton
by
the
which isis the
the proton current
current I(mA),
I(mA), divided
divided by
by the
the target
which
*target
which is the proton
proton current
I(mA), divided
by thetarget
diameter
diameterD(m)
D(m)multiplied
multipliedby
by the
theeffective
effectiveemissivity
emissivityεεε**of
of
diameter
D(m)
multiplied
by
the
effective
emissivity
diameter
D(m)
multiplied
by
the
effective
emissivity
8ofof
the
radiating
surfaces.
theradiating
radiatingsurfaces.
surfaces.
the
the radiating surfaces.
FIGURE
5.5. Measured
irradiation
induced
radial
FIGURE5.
Measuredirradiation
irradiationinduced
inducedradial
radial
FIGURE
FIGURE
5. Measured
Measured
irradiation
inducedmade
radial
displacement
rate
[mm/Ah]
for
the
targets
displacement
rate
[mm/Ah]
for
the
targets
madefrom
fromthe
the
displacement
rate
[mm/Ah]
for
the
targets
made
from
the
displacement
rate
[mm/Ah]
for
the
targets
made
from
the
graphite
grades
R6300P
and
R6400P
[1].
graphitegrades
gradesR6300P
R6300Pand
andR6400P
R6400P[1].
[1].
graphite
graphite grades R6300P and R6400P [1].
The
important
operational
concerns
are
Theimportant
importantoperational
operationalconcerns
concernsare
aremechanical
mechanical
The
mechanical
The
important
operational
concerns
are
mechanical
reliability,
mainly
caused
by
thermal
induced
reliability,mainly
mainlycaused
causedby
bythermal
thermalinduced
inducedstresses,
stresses,
reliability,
stresses,
reliability,
mainly
caused of
by
thermal
which
can
cause
cracking
the
target
cone
spread
whichcan
cancause
causecracking
cracking
ofthe
the
targetinduced
coneand
andstresses,
spread
which
of
target
cone
and
spread
which
can causefrom
cracking
of the target
cone
and
spread
of
radioactivity
evaporation
ofofthe
target
material
of
radioactivity
from
evaporation
the
target
material
of
radioactivity
from
evaporation
of
the
target
material
of
radioactivity
from
evaporation
the target
material
because
of
the
high
temperatures.
Figure
6 shows
the
because
ofthe
thehigh
hightemperatures.
temperatures.of
Figure
shows
the
because
of
Figure
666 shows
the
because
of
the
high
temperatures.
Figure
shows
the
variation
of
the
critical
operational
parameters
(the
variation
of
the
critical
operational
parameters
(the
variation of
the
critical
operational
parameters
(the
variation
of the
the
critical
operational
parametersrate)
(the
temperature,
safety
factor
and
the
evaporation
temperature,
thesafety
safety
factor
andthe
theevaporation
evaporation
rate)
temperature,
the
factor
and
rate)
temperature, the safety factor and the evaporation rate)
REFERENCES
REFERENCES
REFERENCES
REFERENCES
1.1. SGL-CARBON,
SGL-CARBON,D-53170
D-53170Bonn,
Bonn,Germany
Germany
1. SGL-CARBON,
1. SGL-CARBON,D-53170
D-53170Bonn,
Bonn,Germany
Germany
2.2. GMN,
Paul
Müller
GmbH,
D-90411
GMN,Paul
PaulMüller
Müller GmbH,
GmbH, D-90411
D-90411Nürnberg,
Nürnberg,Germany
Germany
2. GMN,
Nürnberg,
Germany
2. GMN, Paul Miiller GmbH, D-90411 Niirnberg, Germany
124