1. Renovation of the 45-year old PS magnets
PS & SPS Days 13. –
Renovation of the 45-year old PS magnets
Th. Zickler
CERN

2. Outline Magnet consolidation program Magnet evaluation procedure
New magnet components
Refurbishment procedure
Test and commissioning
Timetable
Risks for the PS start up in 2006
PS & SPS Days
Jan AT/MEL/MI/tz

3. PS magnet consolidation
In 2003 was decided to split the PS Magnet Consolidation Project into two phases :
Phase I in : Refurbishment of the weakest 40 PS Main Magnets
Phase II in : Refurbishment of the remaining 60 PS Main Magnets
This is for the following reasons:
Budget: The total amount of 20 MCHF was not available, whereas the amount needed for the first phase of about 7 MCHF could be allocated.
Personnel: The strain on the personnel involved in LHC, CNGS & other project under full construction (magnets, vacuum, transport, survey) would have been too high for doing all magnets in
PS as LHC Injector: We believe that after phase I the risk of frequent PS stops due to magnet failures would be sufficiently reduced.  Thus the refurbishment of the other 60 magnets can be delayed and stretched over a longer period.
PS & SPS Days
Jan AT/MEL/MI/tz

4. Evaluation procedure
100 main magnet units are installed in the PS tunnel, 91 of them are still in original state (72 even on original position). The following criteria have been applied to find out the weakest magnets:
The total integrated dose received between 1959 and 2004.
The actual radioactivity.
State of the electrical insulation of the main coils.
State of the PFW cable insulation.
Voltage seen by the main coils during operation.
Foreseen PD testing had to be skipped since it was found to be too time consuming.
PS & SPS Days
Jan AT/MEL/MI/tz

5. Refurbishment sequence
The sequence of the magnet removal and refurbishment is mainly determined by:
Actual radioactivity: less radioactive magnets first
Accessibility: magnets difficult to uninstall will be removed when personnel involved has sufficient experience
Survey constraints: important to avoid removing adjacent magnets from the PS ring at the same time
Magnets installed in the inflector zone (8 magnets): 14 interventions (4 hours) are foreseen during the physics run in 2005 (Booster and ISOLDE needs to stop)
PS & SPS Days
Jan AT/MEL/MI/tz

6. New magnet components
All components to complete 60 magnets have been ordered. New main coils and Pole Face Windings (PFW) are actually in production.
232 new main coils (pancakes) are in production at BINP/Novosibirsk.
Coil prototype has arrived at CERN in December 2004 and was tested successfully.
Series coil delivery will start end of February 2005.
Small delay caused by delivery problems of raw materials from CERN.
Workshop for acceptance test (HV) is in preparation in hall 150.
PS & SPS Days
Jan AT/MEL/MI/tz

7. New magnet components
240 new Pole Face Windings are in production at SIGMAPHI/ France.
PFW prototype has arrived at CERN in December 2004 (not conform to specification).
Pre-series PFW actually in preparation. Arrival at CERN in February 2005.
Series PFW delivery foreseen for end of March 2005.
Already two month delay due to casting problems and delivery delays of connection cables.
Further delays likely due to the complexity of the PFW. SIGAMPHI has underestimated the workload.
PS & SPS Days
Jan AT/MEL/MI/tz

8. Refurbishment procedure
Removing auxiliary equipment installed on the main magnets and in the straight sections.
Carefully labeling and marking all cables and tubes.
Disconnecting the magnet and transport to the workshop.
Cutting out the vacuum chamber by AT-VAC.
Removing all components from the magnet yoke, cleaning and installing new coils and PFW.
Magnet testing.
Re-installation of the vacuum chamber.
Transport back into the tunnel, installation and preliminary alignment.
PS & SPS Days
Jan AT/MEL/MI/tz

9. Refurbishment procedure
Repair will be done by 3 teams of 2 mechanics and one team leader from BINP under the supervision of a CERN technician.
A detailed refurbishment procedure strictly to be followed has been established.
Three magnets can be repaired in parallel, while one magnet is tested.
Refurbishing rate by May 2005: 3 magnet / 2 weeks.
PS & SPS Days
Jan AT/MEL/MI/tz

10. Test and commissioning
Each magnet will be tested individually in the test area in workshop 151 by CERN technicians before going back into the PS tunnel. Electrical, high-voltage, mechanical, hydraulic and interlock tests are foreseen.
The main coil and bus bar insulation will be tested on each magnet directly after re-installation in the tunnel before series connection.
Tests on the entire magnet system once the installation is complete are planned for January High-voltage will be applied to the different types of coils and the bus bars to identify possible problems in time.
Polarity checks on the “Figure of Eight“ windings and the “Back Leg Windings” (BLW) will be done.
PS & SPS Days
Jan AT/MEL/MI/tz

11. Timetable Magnet evaluation Dec 2004
Start removing magnets from the PS
Feb 2005
Start delivery of new main coils
end Feb 2005
Start delivery of new PFW
end Mar 2005
Start magnet refurbishment
Mar 2005
Re-installation of last refurbished magnet
end Dec 2005
Test and commissioning
Jan - Mar 2006
Final magnet alignment
Jan - Feb 2006
PS start-up
Apr 2006
PS & SPS Days
Jan AT/MEL/MI/tz

12. Risk for the PS Start-up
To keep the risks for the start-up in 2006 as low as possible a time margin of three months to solve possible problems is foreseen. Therefore, all magnets will be re-installed in the tunnel before the end of December 2005 regardless of the number refurbished at that time.
The risk of damaging a bus bar during magnet removal is high. Although the number of spare bus bars limited (spares only for four types out of 8 available), the risk for delaying the start-up is low if the problem is identified in time so the bus bar can be repaired.
Further delays in the PFW production are very likely. This will reduce the number of magnets to be refurbished, but has no effect on the PS start-up.
PS & SPS Days
Jan AT/MEL/MI/tz

13. Conclusion 40 magnets are foreseen to be refurbished in 2005.
Apart from delays in the PFW production the project runs as scheduled.
No major risk for the start-up in 2006 identified.
The number of refurbished magnet could be increased up to 56 in case of an extended shut-down.
PS & SPS Days
Jan AT/MEL/MI/tz