Tight turns
The Italian National Institute for Nuclear Physics (INFN) has successfully tested the first model of a new fast-ramping curved dipole magnet. This is great news for CERN, which sees the advance as holding potential for the future of the SPS.
The first model of a new fast-ramping curved dipole magnet being prepared for cryogenic testing at the LASA laboratory (INFN Milano, Italy).
On 16 July INFN introduced an innovative dipole magnet. With a length of some 4 metres, it can produce a 4.5 Tesla magnetic field and achieve a tighter bend than ever before (the bending radius has been squeezed to a remarkable 66.7 metres). This new magnet was designed in the first instance for GSI’s SIS300 synchrotron (in Germany), which will require 60 dipoles of this type.
"Achieving such a tight bend demanded a major R&D effort," stressed Pasquale Fabbricatore, the spokesman of the INFN collaboration responsible for the magnet’s development. "We had to not only demonstrate the technical feasibility of the design but also ensure that the manufacturing process was realistic and dependable." The results presented in July indicate that the efforts have paid off: the test magnet achieved a magnetic field strength of 4.5 T, with a field ramp rate of 0.4 T/sec. "Ultimately, we would like to reach 1 T/sec," says Pasquale Fabbricatore, "but we can’t get there with the current testing set-up." For these first tests, the magnet was positioned vertically and submerged in a liquid helium cooling bath. In the synchrotron, the helium will be in supercritical phase, and the dipoles will of course be horizontal.
"A final test under actual operating conditions will be held next year," says Pasquale Fabbricatore. "It will allow us to evaluate the dipole’s magnetic properties precisely. Before that, we will conduct a second test so as to better understand the magnet's overall behaviour."
"This development is of considerable interest for CERN," confides Lucio Rossi, the former leader of CERN’s Magnets, Superconductors and Cryostats group. "These magnets may well become a part of the SPS+ project, which is being planned as part of the High Energy LHC project and has the purpose of improving the Super Proton Synchrotron. We already expect that the current 2 T magnets will have to be replaced with 4.5 T fast-ramping magnets." The new technology could allow the SPS to continue feeding beams to the highest-energy accelerator in the world for many years to come.
* HE-LHC is planned as the successor to HL-LHC and LHeC, around 2030.
