superconducting ir magnets chen, fusan may 11, 2007
TRANSCRIPT
Superconducting IR Magnets
CHEN, Fusan
May 11, 2007
2/18
Outline• Progress of the superconducting magnets and relevant
systems.– Power supplies and QPS were testified to be workable.– Electronic test was done to the system.– The magnets were cooled down to superconducting temperature.– The whole system was assembled together.
• The first commissioning of the magnets.– All coils were powered to 10~20% operating current.– Quench protection system was proved to be reliable.– Many problems were revealed with the valve boxes.
• Schedule of the second commissioning and field measurement.– The valve boxes are rebuilt and the whole system is reassembled.– The second commissioning is in process.– Magnetic field measurement will be started after commissioning.
3/18
Progress of the PS and QPS• Power supplies met the requirements.
– After months of tuning work, all power supplies were workable.
• Power supply control system fulfilled the required functions.
• Quench protection assembly reacted fast and correctly.– Reaction of the system was tested with dummy load.
• Quench detection system was assembled.– Both hardware and software were ready.
4/18
Progress of the SC magnets
• Electronic test before cooling.– The environment was not ideal.
• Temperature: 25~28ºC Humidity: 95%~100%
– Problems of the valve box.• The insulator failed in the hipot test at ~220VDC wh
en the humidity was higher than 95%.• The temperature sensors were electrically connecte
d to the current leads.• The hipot performance was concerned with the vac
uum of the valve box.
5/18
Progress of the SC magnets
• Monitoring the magnets during cooling.– To monitor the transformation from normal to
superconducting of the coils, we powered the coils with low current (40mA) and monitored the voltage drops across the coils.
6/18
Progress of the SC magnets
• Electronic test after cool-down.– Measured the resistance of gas cooled leads.
– Hipot tests were repeated with all coils.• The grounding resistances of all coils were far less t
han requirement (20Mohm).
7/18
The first commissioning• More study on the hipot problem with BNL expert
s, George Ganetis and Wing Louie.– The grounding resistance of coils ranges from 2 to 800
0 ohms. The resistance decreases when the valve box gets cold.
– The resistance is non-linear and does not start to have current flowing until the voltage is greater then 1 Volt.
– In all circuits the short is at or near the gas cooled lead. But the exact location of the short can not be found.
• Possible causes of hipot failure.– All the electrical insulators used in the current leads ha
ve a creep path that is too small.– The G-10 insulators used on the top of the valve boxes
can collect water.
8/18
Result of grounding resistance testValve Box
Circuit AC Ground
Resistance
DC Ground
Resistance
Shorts
Locations
Current
Tested
Comments
SCQ-A
AS 50 335 AS1-IN,
AS2- 3
AS1-OUT
300 Pre-cooled Leads, Bus Quench
High Ground Current
SCQ 130 363 SCQ-IN
SCQ-OUT250 Pre-cooled Leads, Bus Quench
SCB 563 633 SCB-IN
SCB-OUT10 Low Current Shut-off
SKQ 301 514 SKQ-OUT 6.6 Low Current Shut-off
VDC 244 490 VDC-IN
VDC-OUT5.1 Low Current Shut-off
SCQ-B
AS 126 NA AS1-IN,
AS1- 2
AS1-OUT
250 SC bus went resistive
SCQ 1800 8000 SCQ-IN
SCQ-OUT150 SC bus went resistive
SCB 533 625 SCB-IN 40 High Current Shut-off
SKQ 537 NA NA 40 High Current Shut-off
VDC 710 NA NA 40 High Current Shut-off
* This table quotes from George’s report
9/18
The first commissioning
• New problems of valve boxes– The current leads could not be cooled down.
• The cold ends reached 20K with the flux controllers at max.
• Reached 6K with the bypass valves at max.• AS, SCQ and SCB coils could not be powered more
than 20% operating current, otherwise quenched.
– The sensors could not indicate the temperature of the most critical points.
– The inlet and outlet leads could not be cooled equally because they used common controller
10/18
The first commissioning
• Some typical data and the diagnosis
Vc
Vt
Vs
Warmend
Coolend
Gas CooledLead
Endcan ofthe Magnet
Superconductingbus
Outside Valve Box Area Transfer Line Area Magnet AreaHeliumTankArea
Quenchorigin
The signals monitored during the commissioning
11/18
Data of SCQ
Inlet Vt
146A
162A
58A
Outlet Vt
Inlet Vs Outlet Vs
The SC bus quenches, but the normal region does not expand
The SC bus cannot recover after opening the bypass valve
The SC bus recoveres after decreasing the current with the bypass valve opened
Keeping the bypass valve open, start the second ramping cycle
The SC bus does not quench at 162A
Vt almost equals to Vc and Vs equals to zero for both inlet and outlet
With the flow controller max, start the first ramping cycle
12/18
Data of AS297A
9A
49A
98A
148A
197A
245A
Inlet VtOutlet Vt
Inlet VsOutlet Vs
The Vt difference between the inlet and outlet shows the imbalance of the helium flow
The inlet SC bus quench causes the jump of voltage signals while current increases to ~260A
The normal region does not expand at 297A
It is important to analyze why the outlet does not quench even the Vt higher
13/18
146A
165A175A
185A195A
205A
The normal regions do not expand under 200A
The normal regions expand rapidly after 200A and the quench protection system is triggered.
Inlet VtOutlet Vt
Learn more from SCQ
14/18
The second commissioning• The valve boxes are rebuilt and installed.• The quench detection circuit is set up and tested.• The warm temperature electronic test is performe
d.– The insulation of some temperature sensors on the cur
rent leads is not satisfying.
• The power supplies are improved.• The ps control system is updated.• The interlock between systems is linked.• The cryogenic pipes are connected.Now, the temperature reaches 60K.
15/18
The second commissioning• Next steps: (schedule is tight.)
– Restore the quench protection software. (1 day)– Power the coils to 10~20% current. (5~6 days)
• Tuning the parameters of quench detection system.• Check the ps and ps control system.• Check the quench protection assembly.• Configure the parameters of leads flux controller.
– Power the coils to 50% current. (2 days)– Power the coils to 110% current. (2 days)
• Tuning the power supplies.• Quench training if necessary.
– The same powering procedure for the sync-rad mode. (4 days)
16/18
Schedule of field measurement
• Joint field measurement. (37 days)– Instruments alignment, assembly, de-assembly,
replacement (5 days).– Longitudinal field measurement with
salamander.• Solenoid magnet off (1 day) & on (3 days).
– Excitation curve measurement with stretch-line.• Solenoid magnet off (7 days) & on (7 days).
– Rotating coil measurement (long & short coil).• Solenoid magnet off (4 days) & on (10 days).
17/18
Schedule of field measurement
• Individual field measurement. (33 days)– Instruments alignment, assembly, de-
assembly, replacement (5 days).– Excitation curve measurement with stretch-line
(8 days for one magnet, totally 16 days).– Rotating coil measurement (12 days).
• Long coil and short coil are used at the same time with different magnet.
– Longitudinal field measurement with salamander (2 days).
18/18
Additional topic
• The force and torque of SC magnet coils.
• The special type magnets in IR work well.– Septum bending magnet: ISPB.– Dual aperture quadrupole: Q1a, Q1b.– Narrow quadrupole: Q2, Q3.
Fx [kN] Fy [kN] Fz [kN] Mx [kN·m] My [kN·m]
AS 10.5
HDC(Iop=50A)
±3.9z=770mm
z=1170mm1.48
VDC(Iop=24A)
±3.9z=1020mmz=1400mm
1.49