Superconductivity in the BEPCII
Performance
Q. Qin (秦 庆)
Institute of High Energy Physics
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Outline
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Introduction on the BEPCII
Why we chose superconducting stuffs
How superconducting affects operation
What we benefit from superconducting
Summary
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Linac
Storage ring
BESIII
BSRF
Beijing Electron Positron Collider (BEPC)
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1. Introduction on BEPCII
BEPCII — An upgrade project of BEPC
— A double-ring factory-like machine
— Deliver beams to both HEP & SR
RF
SR
II
RF
I
North
e
e
III
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IP
4
3-ring structure
+
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Design Goals of BEPCII
 Collision
 Beam energy range
1-2.1 GeV
 Optimized beam energy
1.89 GeV
 Luminosity
11033 cm-2s-1 @1.89 GeV
 Full energy injection
1-1.89 GeV
 Synchrotron radiation
 Beam energy
2.5 GeV
 Beam current
250 mA
 Keep the existing beam lines unchanged
BEPCII: One-machine, Two-purpose (HEP, SR)
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The Milestones
Construction started
May. 4, 2004
Dismount of 8 linac sections started
7Dec. 1, 2004
Linac delivered e beams for BEPC
July 4, 2005
BEPC ring dismount started
Mar. 2, 2006
BEPCII ring installation started
Nov. 13, 2006
Phase 1 commissioning started
Aug. 3, 2007
Shutdown for installation of IR-SCQ’s
Oct. 24, 2007
Phase 2 commissioning started
Mar.28, 2008
Shutdown for installation of detector
June 24, 2008
Phase 3 commissioning started
July 19, 2008
First hadron event observed
May 19, 2009
Luminosity reached 3.31032cm-2s-1
Nov. 2006
July 2007
Oct. 2006
Oct. 2007
May 2008
L u m in o s ity (× 1 0
600
4
400
3日
日
月
9日
月
14
日
月
17
日
12
月
23
日
12
月
24
日
1月
12
日
4月
8日
12
1
1
0
9
12
1
1
0
9
12
1
2
0
9
日
1
0
0
9
日
1
1
0
9
5月
2
1
2
0
8
日
1
1
2
0
8
0
21
0
1
3
0
8
2010–2011
7
e- beam current
10
9
1
3
0
8
e+ beam current
0
May 2010
23
8
1
4
0
8
May 2009 WAO'12
1 1 1 1 2 3 4 5
200
Luminosity
1月
5.00E+31
2
3月
1.00E+32
1日
1.50E+32
15
2.00E+32
3月
lum
2.50E+32
July 2008
6
32
3.00E+32
0.00E+00 7
1
5
0
8
800
-2 -1
3.50E+32
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B eam cu rren t (m A )
cm s )
Peak Lum history
2月
Oct. 2005
Sep. 2004
2月
May 2004
January 2004
2. Why we chose superconducting items
In the BEPCII, there are
• Two SC RF cavities (SRF)
— one cavity/ring
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• SC RF
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• In the CD0, 3 NC RF cavities were used instead of 1
SRF each ring, providing energy to beams with a
reasonable bunch lengthening.
• To save the longitudinal space of each ring, and
develop the technology of SC RF, we decided to use
SC RF cavity in the BEPCII
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• Two SC quad/multipolar insertion magnets
(SIM) near the interaction point
— one SIM/ring
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• A compact multipole-coil designed to squeeze y* ,
compensate coupling caused by the detector
solenoid, bend beam to outer ring in SR mode, tune
orbit and coupling by corrector and skew quad coils.
• SIM used for above aim, saving the space in IR,
increasing the strength of quad.
• A scheme of permanent squad near IP was also
considered, but not as good as SC scheme.
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Coil winding layout of SC IR magnet (SIM)
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ISPB
SCQ
IP
Interaction region for the collision mode
SCB
2010-04-12
SCB
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Interaction region for the dedicated SR mode
• One SC solenoid magnet (SSM) in the detector of
BES III
— Higher solenoid field (1.0 Tesla) compared to BES I
and BES II (0.4 Tesla), having better resolution.
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Cryogenic system of BEPCII
Cryogenics Hall for RF
SC RF cavity
Cryogenics Hall and gas
tank farm
SC solenoid
Cryogenics Hall for
SC magnets
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SC magnets
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Cryogenic hall and gas tank farm
Contains:
He compressor systems, VFDs, air
compressor, air drier, ORS, coolingwater system, spare power engine,
gas tank farm, control system
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Tank farm
Two 130m3 ,1.45Mpa
Two 130m3 ,0.73Mpa
One 30m3 ,0.08Mpa
One 5m3 ,6Mpa
One 10m3 ,0.73Mpa
BEPCII north crossing point region
Waveguide
Heater
SRF quench line
LN2 transfer line
UPS
SRF Cavity
Multi-channel
transfer line
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PLC rack
500W refrigerator
LHe dewar
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SRF valve box
SRF Cavity
(Spare one)
NCP hall and cryogenics facilities
Cryogenic transfer line
• The total cooling capacity of the cryogenic system
of BEPCII is 1kW/4.5K, with the power supply
requirement of 800kW.
• Two independent refrigerator systems, each with a
cooling capacity of 500W/4.5K, are adopted to cool
the SC magnets and SC RF cavities.
• Possible area to set up all the cryogenic system with
He transport lines, is the base of adopting SC
technology at the BEPCII
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3. How superconducting affects operation
• Both superconducting and cryogenics system were new to
us at the beginning of the commissioning in 2006.
• Vertical and horizontal tests of SC RF cavities were finished
in May 2006, and ready for operation.
• SC magnets and solenoid were not ready, so a NC scheme
was first adopted to run the machine, called phase 1.
• SIM was installed in 2007, and commissioned as phase 2.
SSM and detector were rolled in IR in 2008, commissioned as
phase 3.
• This helped us to get experiences of SC and cryogenic stuffs
step by step during operation.
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No BESIII detector
IR in phase 1
PEP-II dipole
2016/7/2
BEPC quad
BEPC quad
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3-phase of BEPCII storage ring commissioning
Oct. 2006, Installation completed with NIM at IR
Nov 18, 2006 First beam stored
Mar 26, 2007 First collision
May 14, 2007 Luminosity reached that of BEPC
Phase 1
Oct. 2007, Installation completed with SIM at IR
Oct. 24, 2007 First beam stored
Nov. 18, 2007 First collision
Jan. 29, 2008 Luminosity > 11032cm-2s-1
Phase 2
2008 June. Installation completed with BESIII in the IR
July 19, 2008 First hadron event got with BESIII
April 8, 2009 Luminosity reached 2.3 1032cm-2s-1
May19, 2009 Luminosity reached 3.3 1032cm-2s-1
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Phase 3
Main problems we met
• Quench – SRF & SC magnets
 Quench protection systems were setup to analyze the
reason of quench – SC items problem or due to cryogenic
system problem, hardware or software problems, etc.
 Recover the SC devices carefully after getting the reason of
quench in detail.
 Quench of SIM happened frequently at the beginning of
commissioning, and now decreased gradually.
 Very few quench happened to SSM of detector.
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No. of Quench of SIM
60
50
40
30
20
10
0
2008.07 2009.06
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2010.09 2011.06
2011.11 2012.07
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• Cryogenic system failures
 Abnormal data of control system
 The purification problem of He gas (should be
better than 99.99%), which can cause the ability of
refrigerator lower
 Electrical device failures, such as switcher, etc.
 Aging of main parts, such as turbo of refrigerator
 Other uncontrolled force, such electricity down or
fluctuation, thunder storm, strong wind, etc.
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• Among all the fault time of cryogenic system, about
80% are abnormal data of control system and
impure of He gas
• Features of cryogenic system:
 Long time to recover SC status if failed due to any
reason
 “Fragile” due to environment
 A spare compressor was added last summer
shutdown, and improved the performance this year.
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Availability of BEPCII Cryogenics system
Availability of 1# cryogenic system
(for superconductive magnets)
higher than 95.5%
TBF
×100%
Availability(%) =
TBF+TTR
Availability of 2# cryogenic system
(for superconductive cavity)
higher than 94.8%
TBF: Time between failures
TTR: Time to repair and restoration system
4. What we benefit from superconducting
• Help the machine to get to its design goal in such a
small ring tunnel
• Introduce SC to accelerator in main land China
• Master the accelerator related SC technology
gradually
• Setup the first and biggest cryogenics system for
large scientific facility in main land China
• Get experiences on SC and cryogenics performance,
operation gets more and more smooth…
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• From 2008, we started to study and manufacture
the SC RF cavity, including cavity, HOM damper,
high power coupler, cryo-module, etc., by ourselves.
• A spare SC RF cavity has been finished last year.
Vertical and horizontal measurements were done in
IHEP, and the main parameters are good enough.
Now, it is on the tunnel site as a spare part.
• R&D of SC quad is being carried on in IHEP.
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Summary
• SC technology used in BEPCII brought the SC
application to accelerator in main land China.
• SRF and SC magnets run well in BEPCII, with design
parameter of the hardware, and helped the whole
machine to reach its design goal.
• Operation with SC and cryogenics is getting
experienced, though they are sometimes vulnerable.
• SC benefits us not only on the machine itself, but the
technology development.
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Thanks for your attentions!
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