for SuperKEKB Takuya Kamitani KEK LCWS2014 workshop in Belgrade Serbia 20141008 Motivation We have been developing a flux concentrator FC for SuperKEKB based on the ID: 244749
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Slide1
Flux Concentratorfor SuperKEKB
Takuya Kamitani (KEK)
LCWS-2014
workshop in
Belgrade
(Serbia)
,
2014.10.08Slide2
MotivationWe have been developing a flux concentrator (FC)
for SuperKEKB based on the SLAC/IHEP design.A QWT system of pulsed coil (2.0T) is replaced with an AMD system of
the
FC (3.5T)
and the bridge coils (1.0T).
LCWS2014 in Belgrade (Serbia) 2014/10/8, "Flux Concentrator for SuperKEKB" by Takuya Kamitani
2Slide3
SuperKEKB positron stationLCWS2014 in Belgrade (Serbia) 2014/10/8, "Flux Concentrator for SuperKEKB" by Takuya Kamitani
positron
production
Target
Flux
Concentrator
Bridge
Coils
primary
e- beam
e+ beam
3Slide4
Positron Capture Section
KLY1-5
KLY
1-6
SLED
SLED
LAS 14 MV/m
deceleration & phase slip
& acceleration
LAS
10 MV/m
acceleration
Solenoids
target
+FC
LCWS2014 in Belgrade (Serbia) 2014/10/8, "Flux Concentrator for SuperKEKB" by Takuya Kamitani
LAS : Large Aperture
S-band structure
4
LAS
accelerating
structure
DC solenoid
Positrons are captured by (2m x6) large-aperture S-band structures
(
iris diameter 30mm
)
immersed in a
solenoidal
field
(
0.4T
).Slide5
Offset layout of target & beam-hole
Flux Concentrator
e+
injection e
-
primary
e
-
bridge coils
target
beam
hole
pulse ST
DC QM
pulse QM
top view
rear view
target
offset
3.5 mm
2.0 mm
FC
offset
7
.0 mm
FC
aperture
spoiler
target
diameter
4
.0 mm
hole
diameter
2.0 mm
solenoid
Accel
.
structure
5
LCWS2014 in Belgrade (Serbia) 2014/10/8, "Flux Concentrator for SuperKEKB" by Takuya Kamitani
For pulse-by-pulse
switching of e+/e- injections
,
we have
3.5mm
target
offset
from beam-line axis and
2.0mm dia. beam-hole
on the axis.
Both of them should be within
7.0mm FC aperture
.Slide6
Positron production targetLCWS2014 in Belgrade (Serbia) 2014/10/8, "Flux Concentrator for SuperKEKB" by Takuya Kamitani6
primary
e- beam
tungsten
beam hole
return
yoke
tungsten
target
beam
hole
cooling water
pipe
flux
concentrator
A tungsten target
(
14mm => 4.0 X
0
) is installed in front of FC
with
2mm gap
.Slide7
Spiral slit FCLCWS2014 in Belgrade (Serbia) 2014/10/8, "Flux Concentrator for SuperKEKB" by Takuya Kamitani
The SLAC-type FC has a conical
hole and
a
spiral
slit
in
a copper conductor
slit gap
is
0.2 ~ 0.3 mm
7Slide8
8conductor pipe of FC
LCWS2014 in Belgrade (Serbia) 2014/10/8, "Flux Concentrator for SuperKEKB" by Takuya Kamitani
flux
concentrator
target
a hollow
conductor pipe
is silver-brazed
along the spiral.
pulse currents
are driven through the
conductor
pipe.Slide9
9FC aperture, target & beam-hole
LCWS2014 in Belgrade (Serbia) 2014/10/8, "Flux Concentrator for SuperKEKB" by Takuya Kamitani
FC viewed from downstream
target
beam
hole
The aperture diameters of the FC are
7 mm at entrance
and
52 mm at exit
. Slide10
FC pulse modulator
temporary modulator (~ 6 kA)LCWS2014 in Belgrade (Serbia) 2014/10/8, "Flux Concentrator for SuperKEKB" by Takuya Kamitani
Pulse currents
are driven from a half-spec (
max 6 kA
) temporary pulse modulator. (field strength ~
1.9 T
)
pulse width is
5
m
s
.
A full-spec (
max 12 kA
) modulator will replace this
in 2015 March. The
field
strength will be 3.5 T.
10Slide11
e+ capture section in linac tunnel
LCWS2014 in Belgrade (Serbia) 2014/10/8, "Flux Concentrator for SuperKEKB" by Takuya Kamitani11
Flux concentrator,
target, bridge coil
(inside)
elecron
beam
Installed in beam line in 2014 Apr.
e+ beam commissioning started
in 2014 May.
DC solenoidsSlide12
FC pulse power lineLCWS2014 in Belgrade (Serbia) 2014/10/8, "Flux Concentrator for SuperKEKB" by Takuya Kamitani
12
snubber
circuit
FCSlide13
13The first positron beam after the upgrade
BPM: SP_15_T in front of
target
negative charged particles (e- beam)
give
(-)(+)
bipolar signal
BPM: SP_16_5 after e+ capture section
(+)(-)
signal indicates
positive
charged
particles (e+) !
LCWS2014 in Belgrade (Serbia) 2014/10/8, "Flux Concentrator for SuperKEKB" by Takuya Kamitani
First e+ signal
for
SuperKEKBSlide14
14
e+ yield (achieved 2014 June)
Gun
J-arc
target
Sector-2
end
Q(e+) = 0.12
nC
at DR entrance
Primary Electron
intensity
at target
Q(e-) = 0.60
nC
orbit-X
[mm]
orbit-Y
[mm]
beaminten-sity
[nC]Q(e+) = 0.18 nC
at capture-section e+ yield
(Ye+) =
e+ charge
(
Qe
+)/
primary e- charge
(
Qe
-)
Ye+ =
30%
at capture
section
、
Ye+ =
20%
at SY2 for damping ring
LCWS2014 in Belgrade (Serbia) 2014/10/8, "Flux Concentrator for SuperKEKB" by Takuya KamitaniSlide15
e+ yield vs. FC currentLCWS2014 in Belgrade (Serbia) 2014/10/8, "Flux Concentrator for SuperKEKB" by Takuya Kamitani
15FC
current
6.4 kA achieved (B ~ 1.9T) with a temporary pulse modulator.
Design spec. 12 kA will be achievedwill a full-spec modulator in 2015 spring.
finite e+ yield
at zero current. Slide16
e+ yield vs. bridge coil currentLCWS2014 in Belgrade (Serbia) 2014/10/8, "Flux Concentrator for SuperKEKB" by Takuya Kamitani
16
Bridge coil
current 750 A (full-spec) achieved. (B ~ 1.0 T)
BC zero current
is more critical
than FC. Slide17
SummaryA flux concentrator for SuperKEKB has been
developed and installed in the positron station with the capture section in 2014 April.
Operation current (
6.4 kA => 1.9 T
) is still lower than the design (12 kA => 3.5 T) due to performance limit of the temporary modulator.
Initial e+ beam
commssioning
started
and
first e+ for
SuperKEKB
observed
in 2014 June,
e+ charge and yield still low, but to be improved by boosting FC current and other parameters.17
LCWS2014 in Belgrade (Serbia) 2014/10/8, "Flux Concentrator for SuperKEKB" by Takuya Kamitani