First magnet module of a series for FAIR ring accelerator SIS100 delivered: Cryogenic testing underway


The technology behind the FAIR project is unique and customized in many areas. In the large ring accelerator SIS100, the heart of the future accelerator center FAIR, various sophisticated magnets and entire magnet systems will ensure that the ion beam is precisely guided and focused. The quadrupole modules also belong to them. The first of Series (FoS) has now been completed and delivered to GSI. Before shipment to Darmstadt, the module passed successfully an extensive test program (FAT, Factory Acceptance Test) under room temperature conditions at the manufacturer Bilfinger Noell in Würzburg.

The quadrupole doublet module consists of two superconducting quadrupole units manufactured by the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, and several cryogenic components provided by GSI (such as beam position monitors, ion catcher and thin wall quadrupole chambers). Beside of the integration of the quadrupole module, Bilfinger Noell is also in charge of the manufacturing of the cryostat vessel, the common girder, the thermal shield and other parts.

Before integrating the components, the cold mass – i.e. the part of the magnets to be cooled – needs to be assembled and installed on two common girders. The high-precision positioning of the cold mass required for this is accomplished with special suspension rods, similar to that of the dipole magnets. Overall, the high degree of integration is one of the major challenges of the SIS100 quadrupole modules. The integration of two quadrupole units in one cryostat is a design that deviates from other accelerator facilities.

The advantage of this novel design is that it enables a compact design of the FAIR ring accelerator SIS100, also allows the application of innovative technologies such as cryogenic ion catchers and provides ion-optical advantages. Since this technology has not been realized elsewhere before, the first cold test of the delivered module at its final operating temperature of -270 degrees was a particularly exciting moment for the project team and of great importance for the SIS100 project.

The first cold test was conducted at GSI Series Test Facility for superconducting accelerator magnets (STF). The result: The common girder showed a linear shrinkage but no significant lateral movement of the position of the quadrupole units. The experimental verification of this expected behaviour of the girder at thermal cycling was an important step for the whole SIS100 project. In the coming weeks and months, the module will be evaluated carefully. This will include high-voltage insulation tests and geometrical measurements, investigations on the thermo-mechanical stress and power tests with the main- and correction magnets.

The test program will be accompanied by experts from the Italian National Nuclear Physics Institute (INFN, Istituto Nazionale di Fisica Nucleare). Further tests, the SATs (Site Acceptance Tests) of the entire series of quadrupole modules, will be conducted at the facility in Salerno, Italy, later. In the second half of 2019, various contractual agreements were concluded with the INFN and the University of Salerno. (BP)