Shuqing Zhang

This paper primarily reports on the fabrication and testing results of a 16 T all-REBCO no-insulation (NI) magnet. The magnet is composed of 28 stacked double pancake (DP) coils, with a winding inner diameter of 112 mm and a cold bore diameter of 100 mm. Due to the length limitations of the REBCO tape, joints are required within the DP coils. The maximum stress on the coils reaches 399 MPa. The top and bottom DP coil of the magnet are wound with two REBCO tapes simultaneously to improve the electromagnetic margin. To prevent degradation of the joints under stress, we have designed the joint to be located in the low-stress regions on the outer turns of the coils. The magnet contains a total of 76 joints, of which 49 are lap joints located internally within the DP coils, while 27 are splice joints situated between the DP coils. Finally, the magnet was tested under 4.2 K conditions. When the operating current (I_op) reached 252.3 A, the measured central magnetic field of the magnet reached 16.2 T and maintained stable operation for 30 minutes.

Superconducting magnets are widely used in nuclear fusion reactors, high-energy particle accelerators, steady-state high magnetic fields, etc. Higher magnetic fields and higher operating temperatures are two application trends. High temperature superconducting (HTS) materials are the only choice for high temperature and high field magnets in the future. The first- and second-generation HTS materials have a typical tape structure; their critical performance is magnetic field angle and temperature dependent. A new test facility is developed for an experimental study on the an-isotropic critical current. The field angle can be changed from 0° to 360° with a resolution of 1°. The rotation deviation angle is measured to be 0.2° when the upper part rotates 90°. The temperature can be changed from 4.2 to 80 K. The temperature errors are ±50, ±80, and ±135 mK for 4.2–20, 20–40, and 40–80 K, respectively. The angle dependence of critical current (Ic) of the tested rare-earth barium copper oxide tape within 0°–30° is strong. From 30° to 90°, the sample Ic almost does not change with the magnetic field angle. The implementation of the project will not only promote the structural optimization of HTS tapes but also promote the miniaturization and economical application of HTS magnets.

Superconducting transformer is a typical facility used for inducing ultra-high current for large-scale scientific measurement systems, such as SULTAN-facility at the Centre de Recherches en Physique des Plasma (CRPP) in Switzerland, FRESCA-facility at CERN in Switzerland etc. A new program has been launched at the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) to build a new conductor test facility to investigate the transverse pressure dependence of critical current of various superconducting cables using a compact superconducting transformer and cryogenic electromagnetic press systems. The superconducting transformer can induce a secondary current up to 60 kA, at a background magnetic field up to 15 T at 4.2 K. To measure the induced secondary current at cryogenic temperature precisely, three types of NbTi superconducting coils are designed based on the zero-flux principle to characterize the variation of the measured current. In this paper, the design principle of the cryogenic DC transformer and its commissioning results in a preliminary prototype test device are presented. The measurement results show achievements on accuracy of ±0.6% or less and nonlinearity of better than ±0.25%, which demonstrates the feasibility of the cryogenic DC transformer and provides a reliable technology for the secondary current measurement of a 100 kA superconducting transformer used in the program of Super-X test facility at ASIPP.

To study the electromagnetic behavior of superconducting conductors under multi-physics field coupling and evaluate their reliability, a new superconducting conductor test facility (Super-X) has been developed at the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). The control system of Super-X provides a range of functions including remote monitoring, plant control, data acquisition, timing synchronization, and interlocking protection. It is crucial for the operation of Super-X. Currently, the Super-X prototype is in the developmental phase. To fulfill the requirements for controlling, data acquisition, and interlocking protection of the control system, the control and interlocking protection response time is set to be within 100 ms, with the timing synchronization accuracy of 1ms, and the data acquisition frequency ranges from 1 to 10 kHz. This study presents the design of the control system for Super-X, discusses the system's requirements and specifications, and demonstrates its current integration.

The quench phenomenon is an abnormal process caused by disturbances during the operation of superconducting magnets, which can lead to irreparable damage to the magnet. The DC magnet of the Super-X test facility is wound by cable-in-conduit conductors (CICCs) with a maximum field of 15.7 T and is forced flow cooled with 4.3 K supercritical helium. The heat transfer between layers and pancakes affects the diffusion rate of the normal region in the quench process, therefore a quasi-3D model is proposed to analyze the quench behavior of superconducting coils. A 1D assumption is made for the CICC axially, while taking into account the thermal coupling effect through the inter-turn insulation. The quench process of DC magnets of the Super-X test facility is analyzed and calculated for different operating parameters.

The Central Solenoid Model Coil (CSMC) of the China Fusion Engineering Testing Reactor (CFETR) is currently in the pre-assembly phase. Once completed, the CSMC will be tested on a testing platform. The CSMC test platform consists of six relatively independent subsystems, and during the test, all systems need to coordinate and cooperate to successfully complete the experimental tests. The central control system is used to effectively control these subsystems for carrying out CSMC test experiments according to specific requirements. This article introduces the CSMC test plan and testing signal requirement. A central control system for pulse operation has been developed, utilizing Xilinx FPGA as the hardware platform and implementing the user interface using C# WPF. Additionally, a multilevel cache database management system compatible with both pulse operation and long-term operation has been successfully developed. Furthermore, the CSMC testing platform has reached a stage of completion and is currently undergoing integration testing.