The ZEPTO project is an ongoing collaboration between the Mars group and CERN to develop a new generation of energy saving magnets for particle accelerators. ZEPTO stands for Zero Power Tunable Optics and focuses on using high strength permanent magnet materials to generate shaped magnetic fields without the need for the constant power consumption and cooling inherent in conventional electromagnet technology. The ZEPTO magnets feature moving magnetic blocks allowing them to adjust the strength of their field without significantly changing the shape. This technology will allow future particle accelerators to be built and operated with dramatically reduced energy consumption, lowering running costs and reducing their environmental impact.
The high strength quadrupole
In 2012 we completed the design of the first magnet of the ZEPTO family, a high strength quadrupole focusing magnet with a peak field gradient that can be varied between 15 T/m and 60 T/m without significantly changing the field quality. The steel poles that define the shape of the field remain fixed. Four blocks of NdFeB magnetic material provide the magnetic flux and move in pairs, the magnet blocks pull away from the poles as shown to adjust the field gradient.
A prototype of this magnet design has been constructed and extensive measurements confirm that the design conforms to expectations. Development of this magnet has reached the stage where it is ready for use on accelerators and is commercially licensed with Danfysik. We are currently investigating modular designs of this concept to reduce costs even further and make the design applicable to the widest possible range of needs.
More information is available here.
The low strength quadrupole
In 2013 we completed the design of the second magnet in the ZEPTO family, a low strength quadrupole focusing magnet with a peak field gradient variable between 40 T/m and 4 T/m. This design is intended to be a cheaper and simpler solution where lower field gradients and larger tuning ranges may be necessary and make significant cost savings by using only 2 blocks of NdFeB permanent magnet material. It uses a refined motion system where instead of being pulled apart from the steel poles, the blocks slide along the steel and retreat into a secondary magnetic circuit. This results in significantly reduced magnetic forces and a simpler motion system.
A prototype of this magnet was built in late 2013 and measured in 2014, with results presented at the IPAC’14 conference. This design is also commercially licenced and improvements such as conversion to a modular design are currently being investigated.
More information is available here.
The dipole bending magnet
In 2016 we completed magnetic modelling and the mechanical design of a prototype dipole bending magnet with a central field variable between 1.1 Tesla and 0.45 Tesla. The design works in a similar way to the low strength quadrupole, with a single large block of NdFeB sliding between two steel pole pieces which guide and shape the magnetic field. The magnet block is 500x400x200 mm, making it one of the largest blocks of this high strength material ever produced! This project represents a significant engineering challenge: The force between the magnet and steel is in excess of 8 tons each side, and the design relies on moving a single block without changing the shape of the magnetic field.
The design of this magnet was presented at IPAC’17, and construction of a prototype is currently underway. Upon completion, the magnet will be rigorously tested with a variety of measurement techniques that will accurately map the magnetic field in 3D. We will use the results to assess the suitability of this design for use on future high energy accelerators.
More information is available here.
Technology Demonstrator for diamond
Our latest development in the ZEPTO project is a technology demonstrator to prove the long-term viability of ZEPTO technology for future particle accelerators. STFC has funded the construction of a new ZEPTO prototype to be installed on the booster-to-synchrotron transfer line on the Diamond Light Source in Oxfordshire. This tuneable permanent magnet quadrupole will be installed in early 2021 and will replace the functionality of an existing electromagnetic quadrupole to prove that the ZEPTO technology can give the same performance, without consuming large amounts of power and water.
Notes
The 3 examples of the ZEPTO magnet family listed above are protected under patent WO-2012046036-A1
