Cryo-technical design aspects of the superconducting SIS100 quadrupole doublet modules

Abstract

Abstract. The FAIR project was initiated to build an international accelerator and experimental facility for basic research activities in various fields of modern physics. The core component of the project will be the SIS100 heavy ion accelerator, producing heavy ion beams of uniquely high intensities and qualities. The superconducting main quadrupoles and corrector magnets are assembled within complex quadrupole doublet modules (QDMs), combining two superconducting quadrupole (focusing and defocusing), sextupole and steering magnets in one cryostat. In addition a cryo-catcher, a beam position monitor and a cold beam pipe will be integrated. In accordance with the magnet lattice structure, the QDM series for the SIS100 consists of four main families composed of eleven different configurations. The common technical feature of all configurations is a sophisticated common girder structure, mechanically integrating all functional components in one cold mass and being suspended in a corresponding cryostat system. The requirements to position preservation during thermal cycling are to be fulfilled by a precise and stable support of the functional elements, as well as by a reliable, reproducible and stable cold mass suspension system. The main design aspects of the QDMs will be discussed as a result of these requirements.

Development of integrated superconducting quadrupole doublet modules for operation in the SIS100 accelerator

“…Due to pressurized compensation bellows in the cryogenic supply system have to compensate an angular offset from the adjacent dipole modules of 1.66° , also lateral forces are working at the cold mass suspension system during operation (F lateral ≈ 22 N at up-stream-and down-stream end of the cold mass). The resulting lateral offset ( -X -direction, in opposite direction of the ring center) of ≤ 10 µm [3] during beam operation is also negligible.…”

“…This integrated cold mass is suspended in a system of crossed load-an tie-rods (see figure 1). The requirements on allowed position errors of the cold mass of ∆x, ∆y = ±125 µm for the quadrupole magnets, ∆x, ∆y = ±175 µm for corrector magnets [3], is expected to be acceptably met when applying a correction of a predictable offset in cold mass alignment during module assembly. A design calculation, applying the finite element method to simulate the load cases "warm and ventilated system with pre-stressed suspension system" and "operation at 4 K" was performed for an advanced and detailed module design.…”

“…The He-supply system consists of a LHe-supply line for magnet cooling [8], a LHe-supply line for vacuum chamber cooling, a 2-phase-He return line, a flow restrictor for vacuum chamber supply and other flow restrictors for magnet supply. The cold mass is integrated by a common girder structure and is suspended by a suspension system, composed from crossed load-and tie rods [3]. The fully assembled module (see figure 2) integrates the cold mass by bearing its load rods in suspension domes and retaining additional tension forces of tie-rods in the corresponding lower suspension domes.…”

“…An overview on classes and configurations is given in [3]. During the running design phase, a reduction of different configurations was achieved by eliminating differences in electrical connections of the quadrupole magnets in the straight sections.…”

Literature Review of Suspension Systems for Superconducting Elements

“…The 8-rod architecture has been found in the quadrupole doublets of the FAIR (Facility for Antiproton and Ion Research) [26,27] and the coils of an MRI at NeuroSpin [48,49]. The 8-double-band suspension system has been found in the analytical paper from the CAS (Chinese Academy of Sciences) [32], the wiggler of TLS (Taiwan Light Source) [24], the wiggler of IHEP (Institute of High Energy Physics of CAS) [22], the coupling solenoid of the MICE [25], and the undulator of SSRF [2,3].…”