Cryogenic Systems Engineer

Fuse • San Leandro, CA

9d • $110,000 - $165,000 • Onsite

About The Position

Fuse is constructing Z-Star, a next-generation pulsed-power facility. Z-Star requires two deeply integrated cryogenic systems: a high-vacuum cryopumping system and a 4 K target/liner cryogenic cooling system. As the Cryogenic Systems Engineer, you'll design, commission, operate, and maintain both systems and serve as the facility's resident expert in cryogenic and vacuum science.

Requirements

• B.Sc. or M.Sc. in Physics, Mechanical Engineering, Engineering Physics, or Chemical Engineering with demonstrated cryogenics specialization.
• 2+ years of hands-on experience designing, operating, or maintaining cryogenic systems at liquid-helium temperatures (4 K) in a research or industrial facility.
• Proficiency with cryopump systems including sizing, installation, and regeneration cycles.
• Strong working knowledge of vacuum science and technology: pumping speed, conductance, outgassing, leak detection using He mass spectrometry, residual gas analysis, and pressure measurement.
• Experience designing or operating liquid-helium dewars, cryostats, and VJ transfer lines.
• Familiarity with cryogenic instrumentation including thermometry, pressure, flow, and liquid-level measurement from 4 K to 300 K.

Nice To Haves

• Experience with fusion energy, pulsed power, or particle-accelerator cryogenic systems, particularly high-voltage-isolated cryogenic assemblies.
• Familiarity with MagLIF-type target cryostats or ICF cryogenic target-preparation systems.
• Experience with Gifford-McMahon (GM) or Pulse Tube (PT) cryocoolers for closed-cycle refrigeration.
• Knowledge of cryogenic safety standards including ASME Section VIII, CGA G-5.4, ODH analysis procedures, and pressure-relief system design.
• Experience with large vacuum-chamber systems (>10 m³) in a pulsed or repetitive-shot experimental facility.
• Proficiency in thermal modeling and simulation using ANSYS, COMSOL, or equivalent tools.

Responsibilities

• Design, procure, install, and commission the multi-stage vacuum system for the Z-Star chamber, including turbomolecular roughing pumps, cryopump arrays, and associated gate valves, interlocks, and controls.
• Define cryopump sizing, placement, and regeneration schedules to meet target base pressure and shot-repetition-rate requirements.
• Develop and maintain vacuum protocols including chamber venting, backfilling with inert gas, and controlled pump-down procedures compatible with shot operations.
• Monitor and trend vacuum performance; diagnose and resolve outgassing sources, virtual leaks, and pump degradation.
• Design and commission the liquid helium cryostat and cryogenic delivery system for liner/target cooling, including vacuum-jacketed transfer lines, LHe reservoir management, and temperature-control instrumentation.
• Develop procedures for target loading, cool-down, hold time at 4 K, and rapid warm-up following a shot.
• Characterize and minimize cryogenic heat loads from radiation, conduction, and parasitic pathways to maintain stable 4 K conditions through the target preparation window.
• Manage liquid helium and liquid nitrogen supply, storage dewars, and transfer operations on-site, including logistics, safety, and vendor relationships.
• Maintain all cryogenic hardware: cryopumps, compressors, cold heads (Gifford-McMahon or Pulse Tube), transfer lines, pressure-relief systems, and monitoring instrumentation.
• Develop and implement a preventive-maintenance program for all cryogenic and vacuum equipment aligned with the facility shot schedule.
• Train facility operations staff on cryogenic safety procedures and emergency response.
• Specify, install, and maintain cryogenic instrumentation: Cernox or PT-100 temperature sensors at multiple stages, capacitance manometers, ionization gauges, residual gas analyzers (RGA), and pressure transducers.
• Integrate cryogenic-system monitoring into the facility control and interlock system.
• Author and enforce cryogenic safety procedures, including ODH assessments, pressure-vessel requirements, LHe handling, and cold-burn precautions, in compliance with applicable U.S. codes.
• Perform pressure-vessel and cryostat inspection and documentation per applicable ASME/CSA standards.

Benefits

• Medical, dental, and vision coverage.
• Relocation assistance for roles that require it.
• Flexible time off. Take what you need, no accrual tracking.
• 2 weeks of paid time off built into the end of each year, subject to team and business needs.
• Supportive leave of absence policies.
• Paid leave for new parents.

What This Job Offers

• Job Type: Full-time
• Career Level: Senior