LS1 Report: alive and kicking!

Following eleven months of meticulous maintenance and consolidation works, the LHC's extraction kicker magnets (MKDs) and its pulse generators are back in the accelerator for a new phase of tests. Used to dump the beam, these kicker magnets are essential for the safety of the machine.


Pulse generators for the extraction kicker magnets at Point 6. The high voltage cables leading to the magnets can be seen in red.

The LHC's kicker magnets are something rather special. Unlike most of the accelerator's extraction magnets, they only operate for a short period of time and focus on providing a quick "kick" to deflect the beam. If fact, they are permanently under voltage to be ready to go, and have only 3 microseconds in order to establish their kicking pulse! This means they have to be very powerful - with the help of their own high-powered pulse generators - and extremely well in synch - with the help of control and electronic specialists.

"During this shutdown, we completely removed the kicker's pulse generators from the tunnel, and disassembled them in Building 867 for cleaning, checks and part replacements," says Francesco Castronuovo, LS1 co-ordinator for the LHC Beam Dumping System consolidation. "As we had noticed some limitations in the generators during the first run of the LHC, it was essential to completely consolidate them before the next run. One key update was the replacement of the generator's high voltage connections, which carry a staggering 20 kA and 30 kV!"

Maintenance and consolidation works are performed on the pulse generators in Building 867.

These high voltage connections, of course, also influence the performance of the kicker magnets themselves. During the shutdown, the TE-ABT-FPS team worked on replacing and repairing high voltage semiconductor switches within the MKDs. Some 4,500 components have been individually tested. Hardware tests are being carried out on these switches, as well as the entire kicker magnet chain. Further tests are also ongoing to verify the shape and timing of each magnet's pulse, and ensure that the magnets work together to influence the LHC beam.

"The LHC's kickers are utterly unique; no other magnet can generate such a strong pulse in such a short time," concludes Francesco. "But while this is what makes them special, it also makes them quite a challenge!"

With the generators now reinstalled in the tunnel, two teams from the TE-ABT group have begun a series of hardware tests to see how their improvements work outside of laboratory conditions. These tests began at the end of last year and will take about three months. After this, a team from Operations will take over to ensure the kicker's performance reliability and repeatability. These tests will take a further six months.

Meanwhile, elsewhere

In the LHC, the two major R2E cabling campaigns at Points 5 and 7 are now finishing within schedule, with new cables and connectors being tested. Over in sector 8-1, pressure tests took place on 8 April to qualify the interconnection consolidations. These have been very successful.

The SMACC project continues to progress. A major success was the installation of the final diodes on the quadrupoles at the beginning of the week. Shunts are now being installed across the LHC and the wagon welding the M line has entered its last sector.

Over in the PS, the POPS (POwer for PS) is currently being tested with high voltage and the second phase of tests on the new PS Access System was performed last week. "The global test week of the new PS PSS is almost complete," says Pierre Ninin, project leader of the PS complex safety system. "It has been very fruitful to test the interfaces, dependencies and behaviour of all the safety chains. The outcome is very positive and no critical issues have been found.” The complete system will be validated during the DSO tests of each facility.

Meanwhile in the PS Booster, TE-EPC is testing the power converters and, at the SPS, everything proceeds under schedule.


by Katarina Anthony