Transcript Suoerconductiong guadrupole magnets system in the interaction

Superconducting quadrupole
magnets system in the
interaction region of BEPCII
CHEN, Fusan
Feb. 6, 2007
Outline
 The interaction region (IR) and the
Superconducting (SC) Magnets.
– Introduction of the IR and the SC magnets.
– Winding of the SC magnets.
 The quench protection system (QPS).
– Quench detection system (QD).
– Quench protection assembly (QPA) and the power
supplies (PS) for the SC magnets.
 The commissioning of the SC magnets.
– Problems revealed in the commissioning.
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Interaction region of BEPCII
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The SC magnets for BEPCII
 Coil structure
–
–
–
–
–
3 anti-solenoid.
Main quadrupole.
Main dipole.
Vertical dipole corrector.
Skew quadrupole.
 Powering configuration
– Anti-solenoids are
powered in series with
one main PS.
– Two trimming PS are
used for current tuning.
AS1
AS2
AS3
± 65A
± 65A
1300A
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Winding of the magnets
 Made by BNL/SMD
– Direct wind technology.
• Wind the cable directly onto
the support tube.
– Serpentine style winding.
• Double layers make complete
poles.
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Quench detection system
 Quench detection system (BNL)
– DSP based digital quench detection system.
– Easy to configure, diagnostic and query.
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Quench protection assembly
 Quench protection actions fulfilled by three
sub-systems.
– Quench protection assembly interface chassis.
• QPAIC sends out commands to other systems according to the
quench protection logic resided in the PLC of QPAIC.
• QPAIC can switch the operating mode for synchrotron radiation
mode and collider mode.
– Quench protection assembly and the power supply.
• QPA is integrated into power supply.
• QPA cuts off the powering circuit and switches the energy
extraction resistor into the dump circuit.
– Power supply control system.
• Control system ramps down the power supplies without
triggering the magnets quench at the case of common faults.
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Pictures of QPA
Quench protection assembly interface chassis
Front
Back panel
view of
ofpower
powersupplies
suppliesfor
forSCB(HDC)
SCB(HDC)
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Test of QPA
 Act as predetermined logic
 Fast response
– Quench
• 0.7ms
– Fault
• 5ms
– Coherence
• 7us
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Commissioning of SC
 Maximum test current.
– Anti-solenoid: 300A / 1300A
– Main quadrupole: 205A / 580A
– Corrector coils: ±40A / ±65A
 Quench protection system is proved to be
reliable. (React fast and correctly)
 Problems are revealed with the valve box.
– Coils are grounded with resistance 2~8000 ohms.
– Gas cooled lead cannot be cooled down.
– Main coils quench when currents go beyond 20%
operating current.
– Temperature imbalance between inlet and outlet leads
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Commissioning of SC
 Voltage monitoring during commissioning.
– The voltage drops across the gas cooled lead (Vc)
and across the superconducting bus inside the
transfer line (Vs) are monitored independently.
Outside
Warm
end
Valve Box Area
Gas Cooled
Lead
Quench
origin
Helium
Tank
Area
Cool
end
Vc
Transfer Line Area
Magnet Area
Superconducting
bus
Endcan of
the Magnet
Vs
Vt
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Commissioning of SC/SCQ
162A
146A
With the flow controller
max, start the first
ramping cycle
Keeping the bypass
valve open, start the
second ramping cycle
The SC bus quenches,
but the normal region
does not expand
Inlet Vt Outlet Vt
The SC bus cannot 58A
recover after opening
the bypass valve
The SC bus does not
quench at 162A
Vt almost equals to Vc
and Vs equals to zero
for both inlet and outlet
Inlet Vs Outlet Vs
The SC bus recoveres
after decreasing the
current with the bypass
valve opened
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Commissioning of SC/AS
297A
245A
197A
148A
98A
49A
The inlet SC bus quench causes
the jump of voltage signals while
current increases to ~260A
The Vt difference between the
inlet and outlet shows the
imbalance of the helium flow
Outlet Vt
Inlet Vt
The normal region does
not expand at 297A
It is important to
analyze why the
outlet does not
quench even the
Vt higher
9A
Inlet Vs
Outlet Vs
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Conclusion
 Most of the system work well.
– The performance of the superconducting magnets
is good during the vertical test completed in BNL.
– The quench protection system can protect the
magnets from any quench or faults.
– The power supplies and the control system are
workable although some small bugs still exist.
 We do meet problems.
– Most of the problems occur on the valve box.
 Improvement is underway.
– The valve box is redesigned and under machining.
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