Hardware for Beam Injection and Extraction
Hardware for Beam Injection and Extraction
Y. Shirakabe, Y. Ishi, Y. Mori, I. Sakai, A. Takagi, and M. Tomizawa
Y. Shirakabe, Y. Ishi, Y. Mori,
I. Sakai,
A. Takagi, and M. Tomizawa
KEK, Tsukuba,
Japan
KEK, Tsukuba, Japan
Abstract. The injection and extraction beam-lines of the 50 GeV synchrotron in the JHF project are described. The 50
GeVAbstract.
ring is equipped
with one
from theofpreceding
3 GeV
ring andinthree
extraction
for experimental
The injection
andinjection
extractionline
beam-lines
the 50 GeV
synchrotron
the JHF
project lines
are described.
The 50
facilities
and isforequipped
beam aborts.
Some
of the
features
on the
components,
GeV ring
with one
injection
linecharacteristic
from the preceding
3 GeV
ringinjection/extraction
and three extractionhardware
lines for experimental
particularly
are mentioned.
features arefeatures
intendedontothe
fulfill
two important demands
the kicker
facilitieson
andtheforkickers,
beam aborts.
Some of These
the characteristic
injection/extraction
hardware on
components,
design,
namely, on
a reduction
of reflected
waveforms
a bipolar
fast extraction
by two
the fast
reversedemands
of the kick
direction.
particularly
the kickers,
are mentioned.
Theseand
features
are intended
to fulfill
important
on the
kicker
design, namely, a reduction of reflected waveforms and a bipolar fast extraction by the fast reverse of the kick direction.
In the
following
sections
of this
paper,
thethe
injection
In the
following
sections
of this
paper,
injection
and and
extraction
systems
of of
thethe
50 50
GeV
ring
extraction
systems
GeV
ringis isbriefly
briefly
outlined.
Some
of of
thethe
characteristic
outlined.
Some
characteristicfeatures
featuresononthe
the
injection/extraction
hardware
components,
particularly
injection/extraction
hardware
components,
particularly
on the
are are
thenthen
mentioned.
on kickers,
the kickers,
mentioned.
S3"————:
Insertion
Insertion C
116.1m
RF, Fast Extraction
1^ 50 GeV
GeV Ring
Ring
Circumference
Circumference: 1567.5m
0
A
ion
rt
ert m
Ins 16.1 , Abo ort
1 n
b eV
A
tio
G
ec
at 3
Inj
ion
ect
Inj GeV
at 3
injection
extraction
beam-linesof ofthethe5050
TheThe
injection
andand
extraction
beam-lines
synchrotron
illustrated
FIGURE1.1.The
The
GeVGeV
synchrotron
are are
illustrated
in in
FIGURE
employs
injection
threeextraction
extraction
ringring
employs
oneone
injection
lineline
andand
three
lines.
In the
of the
Insertion
injection
lines.
In the
fastfast
halfhalf
of the
Insertion
A,A,
thethe
injection
preceding
3 GeV
synchrotron
situated.
line line
fromfrom
the the
preceding
3 GeV
synchrotron
is issituated.
second
of the
insertion
providesthetheabort
abort
TheThe
second
halfhalf
of the
insertion
AA
provides
line
at
3
GeV.
This
line
is
supposed
mainly
for
the
use
line at 3 GeV. This line is supposed mainly for the use
in the
commission
stage
order
abortthethebeam
beam
in the
commission
stage
in in
order
to toabort
before
acceleration.
These
lines
designedinina a
before
acceleration.
These
twotwo
lines
areare
designed
symmetric
manner
to each
other
withrespect
respecttotothe
the
symmetric
manner
to each
other
with
center
of
the
Insertion
A.
In
this
way,
the
septum
center of the Insertion A. In this way, the septum
magnet
designs
made
commonbetween
betweenthe
the
magnet
designs
cancan
be be
made
common
insertion
line
and
the
3
GeV
abort
line.
As
for
the
insertion line and the 3 GeV abort line. As for the
kicker
magnets,
however,
designs
similar,
kicker
magnets,
however,
thethe
designs
areare
notnotsimilar,
since the rise-time of the abort kickers is much longer
since the rise-time of the abort kickers is much longer
Abortafter
(up to
to 50
50 GeV)
GeV)
Abort after Acceleration
Acceleration (up
cB 0
Ar m, 12
6.4
40
INJECTION
AND
EXTRACTION
INJECTION
AND
EXTRACTION
BEAMLINES
BEAMLINES
Fast
Fast
Extraction
Extraction
100
200m
Ins
e
Slo 11 rtion
w 6.1m B
Ex
tra
cti
Slo
on
wE
xtr
act
ion
A newly designed synchrotron usually needs to
A newly
designed
usually
needsinto
fulfill novel
demands
that synchrotron
have not been
achieved
fulfill
novel
demands
that
have
not
been
achieved
older generation machines, and those demands mayin
oldernot
generation
machines,
and
demands
may
include,
only a higher
energy
or those
a higher
intensity,
not only
a higher
energy or aand
higher
intensity,
but include,
also new
kinds
of injection
extraction
but also new kinds of injection and extraction
technologies.
technologies.
In the 50 GeV synchrotron in the JHF project, there
In the 50
in the
JHFtoproject,
there
are a number
ofGeV
newsynchrotron
technological
tasks
be solved
are
a
number
of
new
technological
tasks
to
be
solved
regarding the injection/extraction hardware. Since the
regarding the injection/extraction hardware. Since the
ring is aimed to achieve an unprecedented beam power,
ring is aimed to achieve an unprecedented beam power,
the whole system must be designed to counter an
the whole system must be designed to counter an
unparalleled level of radiation damages in order to
unparalleled level of radiation damages in order to
guarantee
reliable
operations
guarantee
reliable
operationsof ofthethemachine.
machine.The
The
injection
andand
extraction
components
injection
extraction
componentsmust
mustsimilarly
similarly
face face
withwith
these
radiation
safety
problems.
these
radiation
safety
problems.
than that of the injection kickers. If kickers can be
than thattheof kicker
the injection
kickers.
If kickers
be
slower,
volume
can be
made can
bigger,
slower, inthea smaller
kicker number
volume ofcan
be units
madeandbigger,
resulting
kicker
costly
resulting
in a smaller number of kicker units and costly
power
supplies.
power supplies.
The Insertion B is for the slow extraction line. This
The Insertion
B is for the
slow extraction
This
contains
one electrostatic
septum,
8 septumline.
magnets,
contains
one
electrostatic
septum,
8
septum
magnets,
and 4 bump magnets. The second half of the Insertion
bump
The second
Cand
is 4for
themagnets.
fast extraction
linehalfforof the
the Insertion
neutrino
C
is
for
the
fast
extraction
line
for
the
oscillation experiment. A special demand toneutrino
the fast
oscillationdevices
experiment.
A special
demandextraction
to the fast
extraction
is to achieve
a bipolar
by
extraction devices is to achieve a bipolar extraction by
reversing
the polarities of the extraction magnets. Its
reversing the polarities of the extraction magnets. Its
detail will be described later.
detail will be described later.
The injection and fast extraction scheme of the
The injection and fast extraction scheme of the
proton
is shown
shown inin
proton bunches
bunches in
in the
the 50
50 GeV
GeV ring
ring is
FIGURE
2.
The
3
GeV
ring
and
the
50
GeV
havethe
the
FIGURE 2. The 3 GeV ring and the 50 GeV have
harmonic
numbers
of
2
and
9,
respectively.
The
harmonic numbers of 2 and 9, respectively. The
required
— rise-times,
rise-times,
requiredtime
time structures
structures of
of the
the kickers
kickers ---
40 Arc
6.4 C
m,
12
0
INTRODUCTION
INTRODUCTION
Arc A
406.4m, 120
FIGURE1.1. Injection
Injection and
and extraction
extraction beam-lines
FIGURE
beam-lines of
of the
the 50
50
GeV
synchrotron
of
the
JHF
project.
The
ring
has
a
threeGeV synchrotron of the JHF project. The ring has a threefold symmetry, hence there are three straight insertion
fold
symmetry, hence there are three straight insertion
sections to which the injection and extraction functions are
sections
to which the injection and extraction functions are
scattered, as are shown in the figure.
scattered, as are shown in the figure.
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
80
W
44
33
4
10
%
2
2
1
1
550
%
50%0%
Injection
Injection
Injection
at
at 3GeV
3GeV
at 3GeV
:
-time
risiem
mee:: c
rrisisee-1-t1tni0s4seenccse
11110044n
3
50
Ring
50 GeV
GeV Ring
Ring 11 V
50
GeV
GeV Ring " "' '
9950
Buckets
9 Buckets
Buckets
9 Buckets
(1 59
(1 5.9687 8nnsse
.67 nMs ecc
M eHHcz
Hz z))
)
(^\
sec z)
se1ecnc zz)H
)
1n5n8s H2HM
7
55881212M.M
7(
(1(1. .7
333GeV
GeVRing
Ring
GeV
Ring
2223Buckets
GeV Ring
Buckets
Buckets
2 Buckets
Fast
Fast Extraction
Extraction
at
Fast
Extraction 1
at 50GeV
50GeV
100%
at 50GeV
%
rise-time:
rise-time:
rise-time:
300nsec
300nsec
300nsec
FIGURE
scheme
of
the
50
FIGURE 2.
2. Injection
Injection and
and
and fast
fast extraction
extraction scheme
scheme of
of the
the 50
FIGURE
2. Injection
and fast extraction
scheme
of the
the 33
50
GeV
ring. Two
Two
successive
GeV
ring.
injected
from
Two successive
successive bunches
bunches are
are injected
injected from
from the
the 3
GeV
Two50successive
bunches injection
are injected
fromAfter
the 3
Gev
ringring.
to the
the
GeV
cycle.
Gev
ring
to
50 GeV
ring
at
one
cycle.
After
Gev ring to the 50GeV
GeVring
ringatatone
oneinjection
injectioncycle.
cycle. After
After
four injection
injection cycles,
cycles,
numbered 11 to
4 in the figure,
four
numbered
figure, the
the 50
50
cycles,
four injection
cycles,numbered
numbered 1toto4 4ininthe
thefigure,
figure,the
the50
50
GeV
ring
is
filled
with
eight
bunches
and
starts
acceleration.
GeV
ring
is
filled
with
eight
acceleration.
filled
with
eight
bunches
and
starts
acceleration.
GeV ring is filled with eight bunches and starts acceleration.
Since
the
harmonic
number
is nine, one
bucket
is
Since
the
harmonic
number
of
the
ring
Since
thethe
harmonic
number
ofof
thethe
ring
one
bucket
Since
harmonic
number
ringisisnine,
nine,one
onebucket
bucketisis
left
empty,
which
allows
aa longer
rise-time
for
the
fast
left
empty,
which
allows
for
the
fast
leftleft
empty,
which
allows
longer
rise-time
for
the
fast
empty, which allows a longer rise-time for the fast
extraction
kicker.
extraction
kicker.
extraction
kicker.
extraction
kicker.
the
kicker
will
make
reflection
pulsesrepeatedly
repeatedlyatat
atthe
the
thekicker
kickerwill
willmake
makereflection
reflectionpulses
pulses
repeatedly
the
the
kicker.
When
the
kicker
is
used
for
beam
injection,
the kicker
willthe
make
reflection
pulses
at the
kicker.
When
the
kicker
used
forrepeatedly
beaminjection,
injection,
kicker.
When
kicker
isisused
for
beam
these
reflected
pulses
cause
seriously
damaging
kicker.reflected
When the
kickercause
is
usedseriously
for beamdamaging
injection,
these
reflected
pulses
cause
seriously
damaging
these
pulses
perturbation
on
the
circulating
beams.
Areduction
reduction
of
these reflected
pulses
causebeams.
seriously
damaging
perturbation
onthe
the
circulating
beams.
reduction
perturbation
on
circulating
AA
ofof
reflected
waveforms
is
an
important
design
issue
for
perturbation
on
the
circulating
beams.
A
reduction
of
reflected waveforms
waveforms isisananimportant
importantdesign
designissue
issueforfor
reflected
reflected
waveforms
the
injection
kickers.
the
injection
kickers. is an important design issue for
the
injection
kickers.
the injection kickers.
In
the 50
50 GeV
GeV synchrotron
synchrotron with
with a ahigh
highbeam
beam
In the
beam
In
In
the
50
GeV
synchrotron
with
a
high
beam
power,
however,
conventional
reduction
techniques
power, however, conventional reduction techniques
power,
conventional
may
nothowever,
be satisfactory.
satisfactory.
is because
becausetechniques
slight
may
may
not
be
ItIt isreduction
a a slight
may not beofofasatisfactory.
Itisisisalways
because
a slight
mismatching
aPFN
PFNsystem
system
always
mismatching
unavoidable,
mismatching
unavoidable,
mismatching
of fraction
afraction
PFN system
is always
unavoidable,
and
evenaasmall
small
reflected
pulses
causedbyby
and
even
ofofreflected
pulses
caused
and
small
and
even
a
small
fraction
of
reflected
pulses
caused
byof
this
mismatchingmay
mayproduce
of
this
level
thismismatching
produceananprohibited
prohibited
levelof
this
mismatching
may
produce
an
prohibited
level
of
the
beamloss.
loss.
the
thebeam
the beam loss.
In
order
keepthe
thereflected
reflectedwaveforms
waveformswithin
In
Inorder
ordertotokeep
waveforms
withina a
In order
to keep
reflected waveforms within
a
harmless
level,
newthe
being
harmless
aanew
type
harmlesslevel,
typeofofevading
evadingmethod
methodisisbeing
being
harmless level, a new type of evading method is being
designed
for the
the 50
50 GeV
GeV ring
injectionkickers.
designed
for
designed
ringinjection
injection
kickers.ItsIts
designed for the 50 GeV ring injection kickers. Its
principle
the
principle isis shown
shown inin FIGURE
FIGURE 4.4. Here,
pulse
Here,
thepulse
pulse
principle is shown in FIGURE 4. Here, the
pulse
reflection
, ,isisadjusted
,rfwhere
reflectiontime,
time,tref
ttref,
ref
adjustedtotobebe3 3x xtrfttrf,
, wheretrftrf
trfis
reflection time, tref, is adjusted to be 3 x trf, where trf isis
the
RF
period.
the
RF
period.
the
RF
the RF period.
In
the 50
GeV case,
trftrfisis 600nsec
In
600nsec(FIGURE
(FIGURE2).
2).
In
600nsec
(FIGURE
2).
In the
the 50
50 GeV
GeV case,
case, ttrf
rf is 600nsec
(FIGURE
2).
Kicker
Kicker
Field
KickerField
Field
Kicker
Field
flat-top
lengths,
and
fall-times
flat-top
lengths,
and
fall-times
derived
from
flat-top
lengths,
and
fall-times
—---can
can
bebederived
derived
from
flat-top
lengths,
and
fall-times--canbe
derivedfrom
from
the
figure.
Here,
the
bunch-to-bunch
the
figure.
intervals
are
thethe
figure.
Here,
thethebunch-to-bunch
bunch-to-bunch
intervals
are
figure.Here,
Here,the
bunch-to-bunchintervals
intervalsare
are
assumed
to
be
50%
of
one
RF
period
assumed
to
be
50%
of
one
at
the
injection
assumed
to to
bebe
50%
ofof
one
RF
period
atatthe
the
assumed
50%
oneRF
RFperiod
periodat
theinjection
injection
energy,
and
90%
at
the
extraction
energy,
and
90%
at
energy.
The
riseenergy,
and
90%
atatthe
the
extraction
energy.
The
riseenergy,
and
90%
theextraction
extractionenergy.
energy.The
Theriserisetimes
for
the
injection
kickers,
the
abort
kickers,
times
for
the
injection
kickers,
and
times
forfor
thethe
injection
kickers,
the
abort
kickers,
and
times
injection
kickers,the
theabort
abortkickers,
kickers,and
and
for
the
fast
extraction
kickers
are
forfor
thethe
fastfast
extraction
kickers
are
SOOnsec,
for
the
fast
extraction
300nsec,
900nsec,
extractionkickers
kickersare
are300nsec,
300nsec,900nsec,
900nsec,
and
1100nsec,
respectively.
andand
HOOnsec,
respectively.
1100nsec,
respectively.
and
1100nsec,
respectively.
P.
P.
S.
P.
S.
P.S.
S.
EEE
LLL
lcable
[m]
lcable
cable [m]
[m]
REFLECTION
TRAPPING
REFLECTION
TRAPPINGMETHOD
METHOD
REFLECTION
TRAPPING
METHOD
REFLECTION
TRAPPING
METHOD
FOR
INJECTION
KICKERS
FOR
INJECTION
KICKERS
FOR INJECTION
INJECTION KICKERS
KICKERS
FOR
FIGURE
FIGURE 3.3.
3. AA
A simplified
simplified scheme
scheme
the
kicker
pulse
FIGURE
ofthe
thekicker
kickerpulse
pulse
FIGURE
simplified
schemeofof
propagation.
propagation.AA
Akicker
kickerpulse
pulseisis
generated
the
power
supply
thepower
powersupply
supply
propagation.
kicker
pulse
isgenerated
generatedatatatthe
supply
(left-end)
the transmission
cable
(left-end)and
andpropagates
propagatesthrough
through
toto
(left-end)
and
cableto
(left-end)
and
propagates
through the
the transmission
transmissioncable
the
kicker
load
(right-end).
The
pulse
is
reflected
at
the
the
kicker
load
(right-end).
The
pulse
is
reflected
at
the
the kicker load (right-end). The pulse is reflected
the
reflected at the
kicker
Some part
kickerand
andreturns
returnstoto
tothe
thepower
power
supply.
ofofthe
the
and
powersupply.
Some part
partof
the
kicker
and
returns
the
supply. Some
pulse
energy
is
reflected
again
at
the
power
supply
and
pulse
energy
is
reflected
again
at
the
power
supply
and
pulse energy
energy is reflected again at the power supply and
pulse
causes
the kicker.
causesthe
thereflected
reflectedwaveform
waveformatat
causes
the kicker.
kicker.
causes
the
reflected
waveform
at the
In
kicker
magnet,
a kicker
magnet,aaa magnetic
amagnetic
magneticfield
fieldis
generated
In In
kicker
magnet,
magnetic
field
isisgenerated
generated
In
aaa kicker
magnet,
field
is
generated
with
PFN
(pulse
forming
network)
pulses.
with
PFN
(pulse
forming
network)
pulses.
ThePFN
PFN
with PFN
PFN (pulse
(pulse forming
forming network)
network) pulses.
pulses. The
The
PFN
with
The
PFN
system
is
connected
to
the
kicker
through
a
long
system
is
connected
to
the
kicker
through
a
long
system isis connected
connected to
to the
the kicker
kicker through
through a long
system
transmission
cable
(FIGURE
3).
The
input
pulses
transmission
cable
(FIGURE
3).
The
input
pulses
transmission cable
cable (FIGURE
(FIGURE 3).
3). The
The input
input pulses
pulses to
toto
transmission
to
Kicker
Field
Kicker
Field
Kicker
Field
Kicker
Field
Load
Load
Load
Load
Transmission
Transmission
Cable
TransmissionCable
Cable
Reflection
Reflection
Reflection
1st
1stReflection
Reflection
1st
Reflection
1st
Reflection
2nd
2ndReflection
Reflection
2nd
Reflection
3rd
3rd
3 fd
3rd
trf trf
trf
tt
t
treftref
tref
FIGURE
A principle
reflection
trappingmethod
methodininorder
ordertotomake
makethe
thereflected
reflectedwaveforms
waveformsharmless.
harmless.When
Whenobserved
observed
FIGURE
4. 4.A principle
of of
thethe
reflection
trapping
FIGURE
principle
ofthe
thereflection
reflection
trapping
method
in order
order to
to
make
the
reflected
waveforms
harmless.
When
FIGURE
4.4. AAthe
principle
of
trapping
method
in
make
the
reflected
waveforms
harmless.
When observed
observed
at
kicker,
the
proton
bunches
(redellipses)
ellipses)
appear
periodically
with
the
RF
period(t(t
rf).The
Thereflected
reflected
waveforms
appear
at
oneone
kicker,
proton
bunches
(red
appear
periodically
with
the
RF
period
rf).
waveforms
appear
at one
one
kicker,
the
proton
bunches
(red
ellipses)
appear
periodically
with
the
RF period
period
(trf).
The reflected
reflected
waveforms
appear
with
a different
period
, which
the
periodto
topropagate
propagate
backand
and
forth
through
thetransmission
transmission
line.IfIfthe
theratio
ratiottrefref/appear
/ttrfrfisis
atwith
the
proton
(red
ellipses)
appear
periodically
with
the
RF
(t
rf). The
waveforms
a kicker,
different
period
of of
tbunches
reft,ref
which
is is
the
period
back
forth
through
the
line.
with
different
period
of
which
the
period
tothe
propagate
back
and forth
forth
through
the
transmission
If
the
ratio
tuned
to be
integer
nttref,
(in
the
above
case,
n=
the
reflected
waveforms
will
alwaysthe
trappedatatthe
theline.
bunch
intervals.
with
aato
different
period
ref
, which
isiscase,
the
period
to
propagate
back
and
through
transmission
line.
If intervals.
the
ratio tref
tref // trf
trf is
is
tuned
be
an an
integer
nof
(in
the
above
n=
3),3),
reflected
waveforms
will
always
bebetrapped
bunch
tuned
to
be
an
integer
n
(in
the
above
case,
n
=
3),
the
reflected
waveforms
will
always
be
trapped
at
the
bunch
intervals.
tuned to be an integer n (in the above case, n = 3), the reflected waveforms will always be trapped at the bunch intervals.
81
Then tref becomes ISOOnsec. If the transmission cable
length
[m],1800nsec.
tref equalsIftothe5 transmission
x 2 x Icable [nsec].
Then tis
ref Icable
becomes
cable
Here,
the pulse
propagation
5[nsec/m],
length5ismeans
lcable [m],
tref equals
to 5 x 2time,
x lcable
[nsec].
Here,2 5means
meansthat
the pulse
propagation
5[nsec/m],
and
the pulse
passes time,
the length
Icable
and 2 i.e.
means
that the
passesFrom
the this
length
lcable
twice,
backward
andpulse
forward.
relation,
twice,can
i.e. be
backward
this relation,
Icable
derivedand
as forward.
tref / 10From
= 180m.
If the
lcable can becable
derived
as istref
/ 10 to
= this
180m.
If the
transmission
length
selected
length,
all
transmission
length
selected
to this
all
the
reflectioncable
pulses
willis be
trapped
in length,
the bunch
the reflection
pulsesthey
willwill
be become
trappedharmless
in the bunch
intervals,
therefore,
to the
intervals, therefore,
circulating
bunches. they will become harmless to the
therefore, are now requested to achieve the reverse of
the kick direction
within a possible
shortest
time. of
therefore,
are now requested
to achieve
the reverse
the kick direction within a possible shortest time.
One of the possible candidates of the PFN scheme
of the possible
candidates
of is
theshown
PFN scheme
to One
realize
fast reversible
kicker
in Figure
to5.realize
the fastisreversible
is shown
in Figure
This scheme
based on kicker
the Blumlein
configuration,
5.which
This scheme
is based
on theproved
Blumlein
configuration,
is widely
used, well
scheme.
In order to
which
is widely
used, wellpolarity
proved scheme.
order to
achieve
the reversible
at the In
kicker,
two
achieve
the
reversible
polarity
at
the
kicker,
two
switches are installed at the both ends of the Blumlein
switches
are installed
at the corresponds
both ends of the
Blumlein
PFN lines.
One switch
to the
normal
PFN
lines.kick,
Oneand
switch
corresponds
to to
thethe
normal
direction
another
corresponds
reverse
direction
another
corresponds
reverse in
directionkick,
kick.and
Since
this PFN
scheme to
is the
composed
direction
kick. symmetric
Since this PFN
scheme
is composed
a completely
manner,
a precisely
equal in
kick
awith
completely
symmetric
manner,
a precisely
equal kick
a reversed
direction
should
be achieved.
The
with
a of
reversed
direction
shouldthebenormal
achieved.
The
choice
the switching
between
switch
and
choice
of the switch
switching
theatnormal
switch
and
the reverse
canbetween
be done
anytime,
therefore
the
canthe
bebeam
done should
at anytime,
therefore
thereverse
decisionswitch
to abort
be possible
until
the
decision
to
abort
the
beam
should
be
possible
until
even the very moment of the turn-on of the normal
even
the very moment of the turn-on of the normal
switch.
circulating bunches.
The length, Icable = 180m, is comparable to the
The between
length, lcable
= 180m,kicker
is comparable
distance
the injection
location into
thethe
50
distance
between
the
injection
kicker
location
in
the
50
GeV tunnel and the power supply building.
GeV tunnel
and theeffect
power
building.
Eliminating
the harmful
by thesupply
reflection
pulses
Eliminating
the
harmful
effect
by
the
reflection
pulses
will be realized with this reflection trapping method.
will be
realized
with study
this reflection
trapping method.
More
detailed
design
is now underway.
More detailed design study is now underway.
switch.
BIPOLAR FAST EXTRACTION BY
BIPOLAR FAST EXTRACTION BY
REVERSIBLE POLARITY KICKERS
REVERSIBLE POLARITY KICKERS
Another merit of employing the Blumlein system is
Another merit of employing the Blumlein system is
that the PFN charging voltage can be reduced by a
that the PFN charging voltage can be reduced by a
factor of 2. The fast extraction kicker requires 0.1 T of
factor of 2. The fast extraction kicker requires 0.1 T of
field strength at the gap height of 100mm, which
field strength at the gap height of 100mm, which
amounts the necessary kicker current of 8 kAT. If the
amounts the necessary kicker current of 8 kAT. If the
normal
PFNimpedance
impedanceisis1010Ω,Q,The
ThePFN
PFNcharging
charging
normal PFN
voltage
becomes
80
kV,
which
is
close
to
the
possible
voltage becomes 80 kV, which is close to the possible
maximum
operating
voltage.
If
the
Blumlein
system
maximum operating voltage. If the Blumlein system is is
chosen,the
thePFN
PFNimpedance
impedancecan
canbebereduced
reducedto to5 5Ω Q
chosen,
with
the
same
time
constant
of
the
circuit
system.
The
with the same time constant of the circuit system.
The
charging
voltage
then
can
be
reduced
to
40
kV.
This
charging voltage then can be reduced to 40 kV. This
valuewill
willallow
allowa asufficient
sufficientsafety
safetymargin
marginforfor
high
value
thethe
high
voltageoperation.
operation.AAdemerit
demeritofofthis
thissystem
systemmight
might
voltage
bebe
that the
thekicker
kickermagnet
magnetmust
mustbebeboosted
boostedto tothethehigh
high
that
voltage
while
the
PFLs
are
charged.
High
voltage
voltage while the PFLs are charged. High voltage
troublesmay
mayoccur
occurmore
morefrequently
frequentlywith
witha longer
a longer
high
troubles
high
voltage operation
operation time,
time, but
but the
thereduction
reductionofofthethe
voltage
maximumvoltage
voltagefrom
from8080kV
kVtoto4040kVkVwill
willfarther
farther
maximum
relaxthe
thewhole
wholehigh
highvoltage
voltagestress.
stress.
relax
The fast extraction line is situated at the
The fast extraction line is situated at the
downstream of the insertion C. The seven kicker units,
downstream of the insertion C. The seven kicker units,
each
one having 1.5m in length and 100mm*100mm
each one having 1.5m in length and 100mm*100mm
inin aperture
to produce
produce the
the strong
strong
aperture size,
size, are
are designed
designed to
enough
kick
with
0.1
T
of
the
kicker
field
to
extract
enough kick with 0.1 T of the kicker field to extract
the
the50
50GeV
GeV beam.
beam.
Recently
emerged to
to the
the fast
fast
Recently aa new
new requirement
requirement emerged
extraction
line,
which
can
be
called
as
the
'fast
extraction line, which can be called as the ‘fast
reverse'
This requirement
requirement comes
comes
reverse’ of
of the
the kick
kick direction.
direction. This
mainly
downstream beam
beam line
lineof
of
mainly from
from the
the fact
fact that
that the
the downstream
the
leads to
to the
the neutrino
neutrino
the fast
fast extraction,
extraction, which
which leads
oscillation
is designed
designed to
to employ
employ
oscillation experiment
experiment line,
line, is
superconductive
magnets.
These
magnets
might
get
superconductive magnets. These magnets might get
quenched
at
anytime,
even
just
very
short
time
—
quenched at
very short time --milliseconds
— before the fast
fast extraction
extraction of
of
milliseconds or
or shorter --the
damaging the
the
the 50
50 GeV
GeV beam.
beam. In order to avoid damaging
quenched
ones, the
the fast
fast
quenched magnets
magnets and the downstream
downstream ones,
extraction
of the
the fast
fast
extraction line
line should have the function of
reverse. Then
Then the
the beam
beam can be extracted
reverse.
extracted in
in the
the reverse
reverse
direction, where
where another beam line,
direction,
line, an
an abort
abort line
line atat50
50
GeV, isis provided.
provided. The fast extraction
GeV,
extraction kicker
kicker systems,
systems,
-20kV, -4kA
T-20kV,
-4kA
-20kV,
-4kA
~2QkV,
~4kA
PFL
PFL
PFL
PFL
i——lUffi1'———1——————1———1————
———HL
R0 = 5Ω = 20Ω//4parallel
VPFN/2
VPFN/2 =40kV
=40kV
R0
SW .
f"T"~;
\ \;
Ro = 5Q = 20Q//4parallel
Gating
GatingSignal
Signalfor
for
Normal
NormalKick
Kick
L
τTo
0 = L / 2R0
= L / 2Ro
R0Ro
= 5Ω
= 20Ω//4parallel
= 5Q
= 20Q//4parallel
Gating
Signal
forfor Gating
Signal
Reverse
Kick
Reverse
Kick
3-
SW
.
r"i""i
R0
FIGURE 5.
5. A
A symmetric
symmetric Blumlein
Blumlein PFN
thethe
bipolar
FIGURE
PFN configuration
configuration ininorder
ordertotoachieve
achievethe
thefast
fastreverse
reverseofofthethekicker
kickerfield
fieldforfor
bipolar
fast
extraction
kickers.
At
the
both
ends
of
the
kicker
(center,
L),
two
PFLs
are
connected
as
in
the
same
way
thethe
fast extraction kickers. At the both ends of the kicker (center, L), two PFLs are connected as in the same wayas as
conventional Blumlein PFN. The difference is that, on the farther sides of the PFLs from the kicker, two switching units are
conventional
Blumlein PFN. The difference is that, on the farther sides of the PFLs from the kicker, two switching units are
connected symmetrically.
connected symmetrically.
82