Physics design of the CiADS MEBT

The superconducting linac for China initiative Accelerator Driven Subcritical System (CiADS) is the world-leading ADS-driver under construction with state-of-the-art technologies. This system is designed to accelerate a 5 mA proton beam to 500 MeV energy, and then delivering 2.5 MW of beam power to the neutron production target. The Middle Energy Beam Transport (MEBT) is designed with great emphasis on smoothing matching between the upstream and downstream acceleration sections, beam diagnostics layout and beam quality control. It is proposed and successfully implemented to immigrate the phase space distortion and reduce the increase of beam emittance. The acceptance of MEBT is optimized to make all the particles inside the effective acceptance of the superconducting section even with machine errors. This pertinent design of MEBT is suitable for the high-power superconducting accelerator of CiADS.

Superconducting Accelerator Magnets Based on High-Temperature Superconducting Bi-2212 Round Wires

Superconducting magnets are an invaluable tool for scientific discovery, energy research, and medical diagnosis. To date, virtually all superconducting magnets have been made from two Nb-based low-temperature superconductors (Nb-Ti with a superconducting transition temperature Tc of 9.2 K and Nb3Sn with a Tc of 18.3 K). The 8.33 T Nb-Ti accelerator dipole magnets of the large hadron collider (LHC) at CERN enabled the discovery of the Higgs Boson and the ongoing search for physics beyond the standard model of high energy physics. The 12 T class Nb3Sn magnets are key to the International Thermonuclear Experimental Reactor (ITER) Tokamak and to the high-luminosity upgrade of the LHC that aims to increase the luminosity by a factor of 5–10. In this paper, we discuss opportunities with a high-temperature superconducting material Bi-2212 with a Tc of 80–92 K for building more powerful magnets for high energy circular colliders. The development of a superconducting accelerator magnet could not succeed without a parallel development of a high performance conductor. We will review triumphs of developing Bi-2212 round wires into a magnet grade conductor and technologies that enable them. Then, we will discuss the challenges associated with constructing a high-field accelerator magnet using Bi-2212 wires, especially those dipoles of 15–20 T class with a significant value for future physics colliders, potential technology paths forward, and progress made so far with subscale magnet development based on racetrack coils and a canted-cosine-theta magnet design that uniquely addresses the mechanical weaknesses of Bi-2212 cables. Additionally, a roadmap being implemented by the US Magnet Development Program for demonstrating high-field Bi-2212 accelerator dipole technologies is presented.

Development of a rotating-coil scanner for superconducting accelerator magnets

The High-Luminosity upgrade project for the Large Hadron Collider (HL-LHC) at CERN (Conseil Européen pour la Recherche Nucléaire) will require new superconducting magnets for the insertion regions. Among these magnets, the new triplet quadrupoles, based on Nb3Sn technology, require magnetic-field measurements of a high precision in the field angle and multipole field errors. In this paper, we present a scanning system based on a rotating-coil magnetometer and its transport system, including the design of the mechanical structure and the induction coils based on printed-circuit-board (PCB) technology. The system and its components are cross-calibrated with other field transducers, such as stretched-wire systems, and their measurement precision is established in a measurement campaign of 2 m long reference quadrupoles.