# Cryogenic Systems Engineer - Company: [Fuse]() - Location: San Leandro, California - Team: Engineering / Technical Ops\. - Employment type: Full Time - Salary: $110K – $165K - Posted: August 19, 2026 ## Job 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 Responsibilities** **Cryopump 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. ## Apply [Apply on Fuse]() Canonical job page: