Division of accelerators, cryogenics and magnetism

The task of LCSE is to master cryogenics technology applied to superconducting magnets, accelerating cavities, physics detectors (cryogenic target systems, calorimeters), and the production and distribution of liquid helium.

For its own developments, and to meet project needs for development and testing, the laboratory designs, builds, and operates several test and characterization stations to determine the mechanical, thermal (see figure), and electrical properties of complete cryogenic subassemblies (such as magnets within cryostats, cryomodules, …), or their basic components (coil cold mass, RF cavities, instrumentation). These stations of various types and sizes use low-temperature refrigeration systems, such as refrigerators or cryogenerators, using the following fluids: helium I and II, nitrogen, argon, neon, or hydrogen.

More specific R&D activities are being carried out on the study and improvement of low-temperature heat transfer systems (helium II in porous media, PHP (pulsating heat pipes) with different gases at cryogenic temperatures), on two-phase flows (thermosiphon with helium I or nitrogen), on the thermohydraulics during magnet "quench", and on the development of cryogenic targets in liquid or solid hydrogen.

At the end of 2020, laboratory staff consisted of 16 engineers, two doctoral students, and six technicians.

The Laboratory for Superconducting Magnet Research (LEAS) offers its expertise in magnetic fields to IRFU physicists, with a staff of 7 technicians, 20 engineers and one PhD student at the end of 2015.

The laboratory teams are responsible for the design and project management of superconducting magnets for experimental facilities, especially large magnets or those with high magnetic fields.

In designing superconducting magnets, LEAS applies its expertise to the optimization of coil geometry, conductor design, mechanical, electromagnetic, and thermal calculations, and magnetic protection in the event of quench. In addition to designing magnets, LEAS has the capacity to manage large projects, to develop magnets and integrate them into cryostats, and to supervise specific industrial projects. Magnets are inspected jointly with the Cryogenics Laboratory and Test Stations (LCSE). Measurement tasks include analyses of tests at ambient and cryogenic temperatures, including quench analyses and magnetic measurements.

Major projects completed recently, such as the GLAD dipole for the R3B spectrometer (reaching completion), or the solenoid coil for the Iseult imaging system, represent R&D work that keeps LEAS staff at its highest level of achievement.

The demand for high magnetic fields is also coming from laboratories such as the French National High Magnetic Field Laboratory (LNCMI) in Grenoble or CERN, in view of future circular accelerators such as the FCC (Future Circular Collider). This demand can only be satisfied by using niobium-tin (Nb3Sn), or high-temperature superconductors based on rare earth elements. These materials have been under active research and development for several years.

Significant developments also involve magnesium diboride (MgB2), which could eventually compete economically with niobium-titanium (NbTi).

The Accelerator Design and Development Laboratory brings together DACM expertise and skills in the design, construction and testing of systems used to produce, transport, accelerate and characterize high-intensity or high-energy charged-particle beams.

As of December 31, 2015, LEDA employed 22 engineers, seven technicians, one PhD student and one engineering intern, working in the following teams:

- A team of experts in beam modeling applied to linear and circular accelerators, in the presence of collective effects such as space charge or wake fields, and in electromagnetic calculations applied to electrostatic, magnetic and radiofrequency systems.

- A technical team experienced in accelerator installation, mechanical assembly and cooling.

- An experimental team specialized in setting up and operating sources and injectors.

- An experimental team of experts for measuring beam parameters, involving the design and implementation of innovative diagnostic techniques.

Building the groundwork for future research, LEDA is currently constructing an accelerator for nuclear physics research (FAIR), contributing to the IFMIF and SARAF neutron source projects, designing a radiofrequency quadrupole for the ESS project, exploring the theoretical and technological aspects of the next generation of particle accelerators (HiLumi LHC, FCC and CLIC), and studying laser-plasma acceleration for the CILEX project.

Between 2013 and 2015, an important R&D program was conducted on ion sources through the development of the ALISES 2 source. In the field of beam diagnostics, LEDA contributed to the development of an innovative emittance meter.

During this period, LEDA also developed its technological platforms by building DIVA, a laboratory for diagnostics, vacuum and assembly activities, while improving its ionsource design and test bench (BETSI) and preparing for startup of the high-intensity proton injector, IPHI. These projects were partially financed by the Ile-de-France Regional Council.

The Cavity and Cryomodule Development and Integration Laboratory (LIDC2) is a center of expertise within DACM, specialized in research on superconducting accelerator cavities and cryomodule integration. LIDC2 provides expertise to support IRFU projects. The laboratory carries out R&D work required to develop cavities from the perspective of both materials (multilayer and polishing) and surfaces (electropolishing and high-pressure rinsing). It participates in the design and development of cryomodules for both French and international accelerators such as SPIRAL2, XFEL and ESS. It is in charge of integrating these systems from the prototype stage. LIDC2 also manages certain shared DACM resources, such as cleanrooms, the chemical treatment facility, materials characterization laboratories and assembly halls.

A staff of 18 engineers and 11 technicians carries out laboratory operations and projects.

The Accelerator and Hyperfrequency Systems Engineering Laboratory represents DACM’s expertise in the design and construction of high frequency electromagnetic structures and their implementation through the use of appropriate instrumentation. At the end of 2015, laboratory staff consisted of 18 engineers and five technicians.

Laboratory activities involve mainly the development of radiofrequency structures for particle accelerators used in physics research (radiofrequency quadrupoles, superconducting cavities, power couplers with highorder harmonics suppression), as well as the associated qualification tools, including RF power sources and instrumentation. The laboratory also manages certain shared DACM resources, such as SupraTech-CryoHF RF test platforms and the new 352 MHz platform. These activities also cover applications in other fields such as antennas for high-field magnetic resonance imaging.

In carrying out its work, LISAH has access to internal expertise within IRFU in the fields of material sciences, process engineering, mechanical construction, and quality assurance. The laboratory also contributes to other IRFU projects, either by taking charge of an entire work package or by providing technical consultancy services.