Cryogenic testing of magnet units: Contracts signed in Dubna
Further important steps toward the completion of the unique superconducting magnets for the future accelerator center FAIR have been taken during the visit of a delegation from GSI and FAIR to Dubna, Russia. In order to guide the particles in a precise beam at close to light speed, FAIR requires hundreds of magnets and complete magnet systems, some of them custom-made. These systems also include a series of superconducting quadrupole units for the large ring accelerator SIS100. Russia is constructing these units as an in-kind contribution to the FAIR project. The contract for the comprehensive test program for this magnet series has now been signed at a ceremony on October 26, 2018 at the Joint Institute for Nuclear Research (JINR).
The 166 quadrupole units, which weigh around a ton each, each consist of a superconducting main quadrupole magnet that is combined in a variety of arrangements with superconducting correction magnets (sextupole and steering magnets). Unlike the usual copper cables, superconducting systems don’t pose any resistance to electric currents. To achieve superconductivity, the units are cooled to around -270 degrees Celsius during operation.
The technology for these magnets, which are very important for the FAIR ring accelerator, has been constantly improved over many years in a joint development program. The main features of this optimization were the minimization of the heat input into the cooling system, the quality of the magnetic field, and the mechanical stability of the magnets during rapid changes in current (high ramp rates) and at high repetition rates. The magnets, which make use of a special superconducting cable known as Nuclotron cable, enable extremely high field strength rise rates of up to four tesla per second — much higher than can be achieved by conventional superconducting magnets.
The quadrupole and correction magnets are being constructed at JINR, thereafter they will undergo the comprehensive test program specified in the contract. This program, which will be carried out in Dubna, includes cooling the magnets to their final operating temperature of -270 Grad and testing the tightness of the hydraulic system and the integrity of the electrical circuits and coils. A facility incorporating a cryogenic system was constructed in Dubna for such tests in a joint project between GSI and JINR during the past years.
Once all of the tests have been passed, the quadrupole units will each be released and transported to Germany, where they will be brought together with other components procured by GSI and assembled into complete modules for the SIS100. This integration and manufacture of the quadrupole modules for the SIS100 by the Bilfinger Noell company, who are also manufacturing the superconducting dipoles for the large FAIR ring accelerator — was commissioned as the result of a call for tenders which was concluded at the beginning of the year.
The ratification of the contract and the commissioning of various companies by JINR means that the series production and testing of the SIS100 quadrupole units can now start. In addition, the delegation, which consisted of the Technical Managing Director of GSI and FAIR, Jörg Blaurock; the head of SIS100/SIS18 Peter Spiller; the head of the department for superconducting magnets and testing (SCM), Christian Roux; and the department employees Alexander Bleile and Egbert Fischer, in the course of the visit signed an additional framework agreement with JINR over further cooperation between the GSI, FAIR, and JINR in the area of superconducting magnets.
Says Jörg Blaurock: “FAIR is a mega project; we have not yet completed all the assignments. This contract offers several possibilities for further expanding our cooperation in the future. The main areas of our cooperation are the production and testing of magnets, but there are also possibilities for the development of techniques and technologies for our experiments, for example, for the CBM experiment.” (BP)