Sr. Mechanical Engineer, Thermal

Aurelius Systems•San Francisco, CA

3d•$160,000 - $205,000•Onsite

About The Position

Aurelius Systems is a VC-backed defense tech startup building autonomous, edge-deployed directed energy systems for counter-UAS. We build laser weapons to shoot down drones. We are a small team of engineers, former US military operators, and subject matter experts scaling America's directed energy dominance. The first cost-effective, reliable, and robust laser weapon system. Our namesake isn't an accident. Marcus Aurelius wrote about doing the work in front of you, every day, without excuses. Henry Ford didn't wait for permission to reinvent manufacturing. That's how we operate — small team, unreasonable output, no hiding behind the unachievable. In addition to our San Francisco lab, we’ve opened a Detroit manufacturing hub and we field test weekly on our own 400-acre private range. We need a Senior Mechanical Engineer with deep thermal expertise to own the thermal architecture of Archimedes, with direct focus on the turret and gimbal that carry the laser source. High-power directed energy systems live or die on thermal management. You'll design, simulate, and prove out the cooling solutions that keep our laser performing at multi-kilowatt power over sustained operation, inside a moving turret, in real-world environments. This is a thermal lead role. You set the thermal design philosophy. You build the simulation framework. You implement cooling loops, heat exchangers, and conduction paths that survive a outdoor environment, not just a lab. You partner directly with the laser, optics, electrical, and controls teams to manage thermal budget across the integrated system.

Requirements

5 to 10+ years in mechanical engineering with primary focus on thermal design and implementation
Practical implementation experience. You've spec'd pumps, sized heat exchangers, selected working fluids, and built systems that hit thermal targets on hardware
Direct hands-on experience implementing cooling solutions for high-power systems.
Strong simulation background in ANSYS Thermal, COMSOL, or equivalent. CFD experience is required for this role, not optional
Deep understanding of conduction, convection, radiation, two-phase cooling, and where each applies
Hands-on test and validation experience including thermal cycling, IR imaging, thermocouple instrumentation, and steady-state characterization
Expert in CAD (SolidWorks, Creo, or similar)

Nice To Haves

Familiarity with turret, gimbal, or rotating-joint hardware is a strong plus. The thermal problem on Archimedes lives inside a moving structure with rotating joints carrying coolant and electrical lines. You don't need to have designed gimbals before, but you need to be ready to work inside that constraint.
Active security clearance or ability to obtain one
Familiarity with MIL-STD-810, MIL-STD-461, and related qualification standards

Responsibilities

Thermal architecture of Archimedes end to end, with primary focus on the turret and gimbal subsystems that house the laser source.
Cooling loop design and implementation including pumps, heat exchangers, cold plates, working fluid selection, and routing through rotating and translating joints.
Thermal simulation in ANSYS, COMSOL, or equivalent. CFD where it accelerates the design decision, not where it justifies one.
Thermal modeling across the optical chain, motor drives, power electronics, and ambient environment.
Heat sink design, thermal interface material selection, and conduction path optimization for high-power-density components.
Test fixture development and execution for thermal qualification including operational thermal cycling, soak testing, and steady-state characterization.
Partnership with the optics team on thermal lensing, beam quality degradation, and stable beam path under thermal load.
Materials selection for thermal performance across metals, ceramics, and composites.