# Cryogenic Systems Engineer at Fuse Cryogenic Systems Engineer at Fuse in San Leandro, California. Full-time, paying $110k–$165k. Posted August 19, 2026. - Company: Fuse - Location: San Leandro, California - Job type: Full-time - Pay: $110k–$165k - Experience: 2+ years - Posted: 2026-08-19 - Apply: https://jobs.ashbyhq.com/fuse/bac78943-8667-4650-a193-0005cd7841f5/application - Source: https://jobmagic.ai/jobs/cryogenic-systems-engineer-fuse-r5tnqv ## Requirements - 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. ## Description ### **About Fuse** We are building one of the most potentially consequential companies of the century. Our mission is to accelerate the world's transition to fusion energy while safeguarding humankind. This is not a normal company. This is not a normal job. We are committed for the long term to win. ### **About the Role** 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. ### **Core ResponsibilitiesCryopump System Design & Operations** - 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. **4 K Target Cryogenic System** - 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. **Cryogenic Infrastructure Management** - 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. **Diagnostics & Instrumentation** - 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. **Safety & Compliance** - 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. ### **Minimum Qualifications** - 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. ### **Preferred Qualifications** - 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. ### **What We Value** - Give a shit. Build things you're proud of. - Take responsibility. If something is broken and you can fix it, fix it. See things through. - Move fast. Make decisions, learn quickly, and keep moving forward. - Think bigger. Simplify relentlessly. Don't default to the safe answer. - Disagree and commit. The best idea wins. Once a decision is made, we move. - Desire to win. This is hard. Expect intensity. We are here to win. - Plan B is to make Plan A work. ### **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. ### **ITAR Requirements** To conform to U.S. Government technology export regulations, including the International Traffic in Arms Regulations (ITAR), you must be a U.S. citizen, lawful permanent resident of the U.S., protected individual as defined by 8 U.S.C. 1324b(a)(3), or eligible to obtain the required authorizations from the U.S. Department of State. ### **Equal Opportunity** Fuse is an Equal Opportunity Employer; employment with Fuse is governed on the basis of merit, competence, and qualifications and will not be influenced by race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, ancestry, immigration status, sexual orientation, gender identity, marital status, mental or physical disability, or any other legally protected status.