Aihua Xu

Rutherford cables are commonly used in ultra-high field Magnetic Resonance Imaging (MRI) magnet systems. In order to solve the problem of whether the toroidal Rutherford cable twist affects the accuracy and uniformity of magnetic field, the parameter equation of the toroidal Rutherford cable is constructed, and the calculation formula of the magnetic field of the toroidal Rutherford cable is derived. The magnetic field calculation results are verified by OPERA software. Secondly, the single-turn Rutherford cable coil model and parallel circular coil model are constructed, and the harmonic components of each order are obtained by left deconvolution method, and the harmonic and field diagram characteristics of the two are compared. The results show that the accuracy of the calculation method meets the application requirements, and the influence of strand transposition in Rutherford cables on the magnetic field uniformity is in the acceptable range. The research results provide a theoretical basis for investigating the uniformity loss caused by the three-dimensional structure deviation of superconducting coils.

In a magnetic resonance system, the magnetic field homogeneity of the imaging area plays a crucial role in imaging quality. However, due to design tolerances and environmental magnetization, shimming is usually necessary to achieve highly uniform magnetic field. And passive shimming, one of the shimming methods, is a widely used technique that utilizes ferromagnetic materials to reduce B0 deviation. Some papers present field contribution of the shims only in the z-direction for the central DSV region, often ignoring the magnetic field in x- and y-directions. This will generate a problem: whether the addition of ferromagnetic shims would cause indelible field deviations for the background magnetic field (BG) in x and y directions, that prone to cause failure to the entire shimming operations. For this reason, this article applied a case study exploring the homogeneity of the BG fields in all the directions and using the ferromagnetic shims for shimming in these three scenarios. First, only the background field is considered. Second, the shims to only optimize the BG fields in the z direction as most literature suggests. And third, the shims optimize the entire three directions adopting our method. Based on this, a practical passive shimming design scheme is provided. Through the optimization, it is found that the new method not only significantly improves BG fields in all the directions, greatly reducing the deviation of tilt angle of the total magnetic field B0 relative to the z-axis, but also no more increases in design difficulty nor consumption of ferromagnetic materials which greatly improve efficiency for the entire shimming procedures. The design theory of this article is a practical method for magnetic resonance imaging (MRI) shimming, which has certain guiding significance for various MRI applications.

As a crucial part of the Central Solenoid Model Coil (CSMC), the preload system is crucial to maintain the integrity of the coil modules and to prevent their offset and misalignment after energization. The purpose of this study is to ascertain the safety and dependability of the preload system components when subjected to extreme alternating currents, through a comprehensive analysis of electromagnetic-structural coupling and an assessment of stress levels. Initially, an eddy current calculation model for the preload system of the CSMC was established using ANSYS Maxwell, and the eddy current, magnetic density, and electromagnetic force density for the preload system were calculated, when subjected to alternating excitation current. Subsequently, an indirect coupling technique was utilized to examine the mechanical behaviour of the preload system, considering the combined effects of extreme electromagnetic loads and preload. Ultimately, the stress levels of the preload system were evaluated using stress linearization, with reference to analytical design principles. After stress assessment, it was found that all types of primary stresses in the preload components were below the corresponding stress thresholds, with sufficient safety margins. This study provides theoretical guidance for the energized testing of the CSMC and serves as an important theoretical basis for further optimizing the preload components.

To address cracking and deformation in large-size ceramic slabs during firing induced by thermo-structural coupling, this study established an indirect thermo-structural coupling finite element model in Ansys to analyze an 820 mm�100 mm�6.32 m...

The Institute of Plasma Physics Chinese Academy of Sciences (ASIPP) has announced a project to design a 14 T MRI magnet with a 900 mm warm bore and comprised of Nb3Sn Rutherford cables, the homogeneity of the magnetic field is better than 0.5 ppm in a 22 cm diameter spherical volume. This paper presents three design schemes for 14 T MRI magnets based on manufacturing technology perspective, which are layered solenoid design, multicoil design and multi-coil layered design, and compares them from the aspects of mechanical design, inductance and total conductor usage to obtain the optimal scheme

The Institute of Plasma Physics Chinese Academy of Sciences (ASIPP) has announced a project to design a 14 T MRI magnet with a 900 mm warm bore and comprised of Nb ₃ Sn Rutherford cables, the homogeneity of the magnetic field is better than 0.5 ppm in a 22 cm diameter spherical volume. The diameter of main coil is about 4 m and the total weight is about to 130 tons. This article describes structural design of 14 T MRI suspension system. A global finite element model is created based on the design geometry data to investigate the mechanical property of the suspension system under the seismic load.

A large scale research and development project for China Fusion Engineering Test Reactor (CFETR) named the comprehensive research facility for fusion technology (CRAFT) started in 2019 and is scheduled for completion in 2025. A super-conducting conductor experiment testing platform (Super-X for short) is a sub-task of CRAFT to evaluate the future supercon-ducting part performance. The maximum testing magnetic field at bore center is 15 T, the dimensions of testing space are 100 × 160 × 550 mm, the field homogeneity of testing space is superior to 95%, and the maximum testing current is 100 kA. The direct current (DC) magnet is the key sub-system for the facility provid-ing the background magnetic field. The engineering design for DC magnet has been accomplished in the middle of this year, and its technical parameters meet the required. The main work focus-es on the structural design of the split coils, the axial preload and the hanging assembly. This paper presents the progress on the engineering design of the DC magnet.

AbstractChina Fusion Engineering Test Reactor (CFETR), a new tokamak device, is under concept design based on the expe-rience of Experimental Advanced Superconducting Tokamak (EAST) and ITER. Research and development of TF coil for CFETR is carried out by ASIPP. TF coil is winding by Cable in-Conduit Conductor (CICC). Main manufacturing process of CICC includes welding of jacket, draw lead, winding and global helium gas tightness test. After winding, the diameter of TF con-ductor is about 4 m and the weight is about to 30 t. This paper describes structural design of dewar which is used for the global helium gas tightness test for the TF conductor after winding. A global finite element model is created based on the design geome-try data to investigate the mechanical property of the dewar un-der static load and seismic load. Index TermsCFETR, TF coil, dewar, mechanical analysis, seismic performance analysis

Feasibility study of ITER In-vessel coils bracket manufacture and integration had been developed in Institute of Plasma Physics, Chinese Academy of Sciences. The ITER In-Vessel Coil system is comprised of Edge-Localized Mode (ELM) and Vertical Stabilization (VS) coils. The ELM coils are used to mitigate the Edge Localized Modes and the VS coils are used to provide Vertical Stabilization of the plasma. Designed bracket for IVC coils is a kind of building block type three or four stacked components with arcuate groove matching with round conductor. This paper describes structure design, manufacture and integration process of the ELM and VS bracket. R&D of bracket weld and assembly sequence optimization are carried out to determine the welding and assembly process. At last, three brackets are integrated in ASIPP.