Principal Magnet Cryogenics Engineer

Thea Energy is leveraging recent breakthroughs in stellarator physics and engineering to create a faster and simpler approach to commercialising fusion energy. The company is reinventing the stellarator using computer-controlled arrays of planar coils, replacing the intricate modular magnets required in all other stellarator architectures. This Principal Magnet Cryogenics Engineer leads the complete programme lifecycle, from concept through commissioning, of large-scale cabled high-temperature superconducting (HTS) magnet systems for next-generation fusion reactors. The role holds end-to-end technical ownership of cryogenic design, thermal-hydraulic modelling, forced-flow cooling distribution and cryogenic integration for cable-in-conduit conductor (CICC) or advanced stacked-tape HTS magnets, bridging megawatt-scale cryogenic plant engineering with microscopic thermal-hydraulic magnet behaviour while leading multi-disciplinary teams through multi-million-dollar hardware deliverables.

Key Responsibilities

• Lead the complete lifecycle of large-scale HTS fusion magnet cryogenic systems, covering conceptual, preliminary and detailed design, qualification, fabrication, assembly, commissioning and decommissioning
• Design, model and validate gaseous helium or sub-cooled liquid nitrogen thermal management systems for high-field cabled HTS conductors, including stacked HTS conductors
• Perform dynamic thermal-hydraulic analysis, transient load modelling (nuclear heating, AC losses, eddy currents, ramp rates) and margin calculations under operational and fault conditions
• Own the cryogenic response strategy during quench events, including rapid helium expansion, overpressure relief sizing, burst disc integration and thermo-mechanical stress containment
• Define requirements for megawatt-class cryogenic plants, cold compressors, heat exchangers, sub-coolers, helium distribution (valve) boxes and low-heat-leak transfer lines
• Oversee cryogenic thermal management for high-current demountable or permanent HTS joints and conduction-cooled hybrid HTS/LTS gas-cooled current leads rated at 60 kA and above
• Manage major subcontracts for large-scale cryogenic infrastructure, conductor fabrication, pressure vessels and vacuum insulated systems (cryostats)
• Plan and execute full-scale cryogenic and high-current magnet test campaigns, leading cool-down, steady-state operation, quench mitigation and warm-up procedures

Requirements

Essential:

• 10 to 15+ years of direct experience in cryogenic engineering and thermal-hydraulic design for superconducting magnet systems, focused on HTS tape and cable architectures (REBCO/BSCCO)
• Proven ownership of large-scale magnet work packages above $10M within fusion programmes (for example W7-X, ITER, JT-60SA, KSTAR, DEMO) or major scientific facilities (for example CERN, Fermilab)
• Demonstrated expertise in high-current (tens of kA) cabled HTS configurations, such as CICC and stacked-tape conductors, and forced-flow cooling strategies
• Experience taking at least one major superconducting magnet or cryogenic system from initial concept through cool-down and operational validation
• Deep familiarity with pressure vessel standards at cryogenic temperatures (ASME BPVC Section VIII, EN 13445, B31.3) and cryogenic safety standards (ISO 21010, CGA)
• Solid understanding of HTS material physics, including REBCO critical surfaces, strain sensitivity, thermal margin assessment and current sharing regimes
• Mastery of low-temperature fluid dynamics for gaseous helium and sub-cooled liquid nitrogen, using database tools
• Deep knowledge of transient thermal analysis, including AC losses (coupling, hysteresis, flux creep), nuclear volumetric heating, heat-leak budgets and thermal shielding (MLI design)
• Extensive knowledge of low-temperature thermometry (Cernox, TVO, optical fibres/FBG), cryogenic flow meters, pressure transducers and valve telemetry
• Proficiency in finite element analysis and thermal-hydraulic modelling tools (for example COMSOL Multiphysics, ANSYS Thermal/CFD, MATLAB/Simulink)
• Ability to write system requirement documents (SRDs) and interface control documents (ICDs), and to lead major design reviews (CoDR, PDR, CDR)
• Demonstrated ability to lead cross-functional teams across structural, electrical, vacuum and systems disciplines, and to mentor junior magnet and cryogenic engineers
• Mastery of FMEA applied to cryogenic system failures, loss of vacuum and runaway quench scenarios

Desirable: none specified in the source listing. Thea Energy notes that it is not necessary to meet all of the listed skillsets and invites candidates to explain why they would still be a great fit.