The Science Behind Superconducting Magnets

Superconducting magnets represent a pinnacle of modern physics engineering, leveraging materials that exhibit zero electrical resistance and expel magnetic fields when cooled below a critical temperature. A superconducting magnet operates by passing electric current through coils made of superconducting wires or tapes, generating intense magnetic fields without the energy losses associated with traditional copper electromagnets. The key is superconductivity, first discovered in 1911 by Heike Kamerlingh Onnes, where certain materials like niobium-titanium (NbTi) or high-temperature superconductors (HTS) such as rare-earth barium copper oxide (REBCO, often called YBCO when yttrium-based) transition to a superconducting state.

In low-temperature superconductors (LTS), cooled by liquid helium to around 4 Kelvin, fields up to 10-15 Tesla are common. For higher fields, HTS materials like REBCO tapes enable operation at 20-77 Kelvin using liquid nitrogen or cryocoolers, crucial for compact, efficient designs. The process involves winding these tapes into solenoid coils, often in a no-insulation configuration to self-stabilize against quenches—sudden loss of superconductivity. Cooling systems maintain cryogenic temperatures, while persistent current switches allow continuous operation without power input once ramped up.

• Step 1: Material selection—LTS for outsoles, HTS inserts for peak fields.
• Step 2: Coil fabrication—multi-layer windings with precise alignment.
• Step 3: Cryogenic assembly—vacuum-insulated Dewar with multilayer insulation.
• Step 4: Ramp-up—gradual current increase to avoid mechanical stress from Lorentz forces.
• Step 5: Operation—stable field for experiments.

This technology underpins MRI machines (1.5-7T), particle accelerators like the LHC (8.3T), and now pushes boundaries in user facilities for materials research.

China's Record-Breaking 35.6 Tesla Achievement

On January 26, 2026, researchers at the Synergetic Extreme Condition User Facility (SECUF) in Beijing's Huairou Science City successfully generated a central magnetic field of 35.6 Tesla using an all-superconducting user magnet with a 35-millimeter usable bore. This marks the world's strongest such magnet designed for open-access experiments, surpassing their own 30T milestone from 2023. Led by teams from the Institute of Electrical Engineering (IEE) and Institute of Physics (IOP) under the Chinese Academy of Sciences (CAS), with key contributors Li Gang, Liu Jianhua, Zhou Benzhe, and Luo Jianlin, the magnet integrates a high-temperature superconducting (HTS) insert—likely REBCO-based—for the peak field, atop LTS outsoles.

The facility, accepted nationally in February 2025, combines ultra-low temperatures, high pressures, and ultrafast optics, enabling multifaceted experiments. Stability exceeds 200 hours at full field, with low energy consumption compared to hybrid resistive-superconducting systems that guzzle megawatts continuously.

Technical Innovations Driving the Breakthrough

The magnet's design emphasizes an all-superconducting architecture, eliminating resistive elements for efficiency. The HTS insert, core to reaching 35.6T, employs advanced winding techniques to handle immense Lorentz stresses—up to hundreds of tons compressing the coils. No-insulation windings distribute currents evenly, preventing hot spots during quenches. Cryogenic engineering ensures uniform cooling, likely using conduction-cooled HTS with pulse-tube cryocoolers for reliability.

China's progress stems from national investments in the 14th Five-Year Plan, prioritizing extreme condition platforms. From Hefei's hybrid 45.2T magnet (resistive + SC) to Beijing's all-SC user magnet, this reflects matured domestic manufacturing of kilometer-long REBCO tapes with critical currents over 500 A/mm-width at 20K, 20T.

• HTS tape enhancements: Higher critical current density (Jc > 1 MA/cm²).
• Structural reinforcements: Carbon composites against hoop stress.
• Precision monitoring: Quantum sensors for field homogeneity < 1 ppm/cm.

Global Context and Record Comparisons

Prior to this, the strongest all-superconducting magnets hovered around 32T (e.g., LANL's REBCO insert in LTS outsoles). Japan's Tsukuba reached ~34T in lab settings, but with smaller bores unsuitable for users. Hybrids like NHMFL's 36T or Hefei's 45T+ require 20+ MW power, limiting uptime. China's 35.6T all-SC user magnet, with its 35mm bore, uniquely balances field strength, accessibility, and efficiency—12-24x clinical MRI fields, 700,000x Earth's.

This leap positions China as a leader in HTS magnetics, rivaling US/EU efforts under ARPA-E and Horizon Europe.

Applications Revolutionizing Materials and Life Sciences

High fields probe quantum matter: de Haas-van Alphen oscillations reveal Fermi surfaces; Shubnikov-de Haas pinpoints carriers in 2D materials like graphene or topological insulators. In life sciences, NMR at 35T boosts resolution for protein structures, aiding drug discovery.

Other probes: magnetocaloric effect for quantum cooling, magnetostriction for smart materials. For fusion, simulates tokamak fields for CFETR (China Fusion Engineering Test Reactor), testing HTS coils for DEMO reactors.

• Nuclear Magnetic Resonance (NMR): Atomic-level biomolecule mapping.
• Specific Heat: Phase transitions in cuprates, iron-pnictides.
• Magnetotransport: Hall effect in Weyl semimetals.
• Quantum Oscillation: Band structure in novel superconductors.

Implications for China's Higher Education and Research Ecosystem

As a user facility, SECUF opens to domestic/international teams, including university researchers from Tsinghua University, Peking University, and University of Science and Technology of China (USTC). This democratizes access to extreme conditions, fostering PhD training and postdoc projects in condensed matter physics. China's universities, with 5,000+ institutions, benefit from such platforms, accelerating publications in Nature and Science.

Stakeholders: Faculty gain data for grants; students hands-on extreme physics. Cultural context: Aligns with 'Science and Technology Self-Reliance' drive, boosting STEM enrollment amid US-China tech tensions.

Explore research jobs in superconductivity or postdoc positions at leading Chinese labs.

Challenges Overcome and Lessons Learned

Developing 35T+ all-SC magnets faces quench protection, mechanical stability (stresses ~100 MPa), and tape uniformity. Teams iterated designs, using finite-element modeling for stress distribution and AI-optimized windings. Case: 2023's 30T quench informed 2026 upgrades.

Risks: Thermal runaway, eddy currents. Solutions: REBCO's high stability, graded doping for Ic grading.

Future Outlook: Beyond 40 Tesla

Plans target larger bores, >40T fields via next-gen REBCO (Jc 2+ MA/cm²) and CORC cables. Integrates with quantum computing (topological qubits) and maglev trains (200+ km/h efficiency). Globally, accelerates fusion timelines, sustainable energy.

For academics, signals booming careers: professor jobs in materials physics abound. China's R&D spend (2.55% GDP) fuels this trajectory.

Career Opportunities in High-Field Magnet Research

This breakthrough spotlights demand for experts in cryogenics, materials fabrication. Chinese universities partner on CFETR, EAST upgrades. Actionable: Pursue MSc/PhD at USTC Hefei or IOP; apply via faculty positions.

• Skills: COMSOL modeling, tape testing, quench dynamics.
• Salary: 200k-500k RMB/year for postdocs/professors.
• Visa: Talents programs for internationals.

Check academic CV tips for applications.

Photo by zhang kaiyv on Unsplash

Conclusion: Pioneering the Frontiers of Science

China's 35.6T magnet heralds a quantum leap, empowering discoveries across disciplines. For aspiring researchers, it's a call to engage—rate professors on Rate My Professor, hunt higher ed jobs, or seek career advice. As facilities like SECUF proliferate, global collaboration thrives, promising transformative tech.