---
title: 'Senior Mechanical Engineer at Hexium'
canonical: 'https://feeny.ai/job/senior-mechanical-engineer-hexium-livermore-da3w97zt5wcq'
type: 'job'
last_seen: '2026-09-16'
---

# Senior Mechanical Engineer at Hexium

- **Company:** Hexium
- **Location:** Livermore, CA
- **Posted:** 2026-09-11
- **Last confirmed live:** 2026-09-16
- **Apply:** https://job-boards.greenhouse.io/hexium/jobs/4404564009

## Job description

Hexium is modernizing Atomic Vapor Laser Isotope Separation (AVLIS), a laser-based isotope enrichment technology originally developed and demonstrated at Lawrence Livermore National Laboratory (LLNL). We are advancing AVLIS into a scalable, industrial-grade enrichment platform designed to strengthen domestic energy infrastructure, industrial resilience, and national security.

## Role

We're hiring a Senior Mechanical Engineer to lead the translation of decades of AVLIS research and development into modern, manufacturable hardware. Initially based on-site at Lawrence Livermore National Laboratory (LLNL) in Livermore, CA, you'll work through legacy technical records to identify the most relevant mechanical designs, reconstruct them as modern 3D assemblies, and identify gaps requiring further engineering. You'll collaborate with national laboratory scientists and engineers as needed to resolve technical questions and inform the modernized design.

From there, you'll advance designs through simulation, prototype hardware, and test fixtures, while serving as a mechanical design authority for Hexium's initial prototype and pilot systems. This is foundational engineering work that will bridge national laboratory R&D with the systems needed to advance AVLIS toward commercial application.

As the program progresses, this role will transition to a Hexium production facility and will require relocation.

## Key Responsibilities

- Review and assess legacy AVLIS mechanical designs and technical records at a DOE national laboratory, working within required classified-handling procedures
- Own mechanical design of chamber and vacuum systems, including all system interfaces
- Apply vacuum system design to materials compatibility selection, outgassing mitigation, and contamination control
- Convert legacy designs into modern 3D CAD assemblies and validate them via thermal/structural simulation
- Work directly with national laboratory scientists and engineers to close technical design gaps
- Collaborate with Hexium's Integration Team on prototype procurement and testing requirements
- Qualify vacuum suppliers and custom equipment fabricators
- Define facility and utility interface requirements for prototype and pilot systems
- Partner with Nuclear Safety on design compliance

Required Qualifications

- 6+ years of mechanical engineering experience, including vacuum system design and/or precision mechanical hardware
- Bachelor's degree in Mechanical Engineering or closely related field
- Proficiency in 3D CAD (SolidWorks, Creo, or similar)
- Must currently hold an active DOE Q clearance or active DOD Top Secret clearance, or have held DOE Q / DOD Top Secret clearance within the past 18 months
- Must be a U.S. Person (required for access to export-controlled technical data)
- Willingness to work on-site full-time at Lawrence Livermore National Laboratory initially, with required relocation to Hexium's production facility (location not yet determined) as the program progresses

## Preferred Qualifications

- Experience with specialty alloys and refractory metal fabrication
- Experience with high-temperature vacuum processes
- FEA/thermal simulation experience
- Background in safety-critical hardware (aerospace, nuclear, defense)

Physical Requirements

- Extended periods reviewing physical archival documents and fine-detail technical drawings, requiring sustained close visual focus
- Fine motor skills and dexterity for precision component assembly and inspection
- Ability to work in confined spaces around vacuum hardware
- Occasional lifting up to 50 lbs
- Extended periods standing/moving within a lab environment

Work Environment

On-site at a DOE national laboratory in Livermore, CA, with standard site security and classified-handling protocols. Role will transition to a separate Hexium production facility as the program scales.

## Benefits

- Stock Options
- Paid Time Off
- 401(k) Matching
- Medical, Dental, Vision insurance
- HSA & FSAs

E-Verify: Hexium Inc. participates in E-Verify. All new hires are required to complete the I-9 employment eligibility verification form and provide documentation to confirm their identity and authorization to work in the United States.

Screening: Employment is contingent upon successful completion of a background check.

Please note this job description is not designed to cover or contain a comprehensive listing of activities, duties or responsibilities that are required of the employee for this job.

Hexium Inc. is an Equal Employment Opportunity Employer. We provide equal employment opportunities to all employees and applicants for employment and prohibit discrimination and harassment of any type without regard to race, color, religion, age, sex, national origin, disability status, genetics, protected veteran status, sexual orientation, gender identity or expression, or any other characteristic protected by federal, state, or local laws. Hexium Inc. is committed to ensuring equal access and providing reasonable accommodations for applicants and employees with disabilities upon request. If reasonable accommodation is needed to participate in the job application or interview process,  please contact Hexium’s Human Resources at HR@hexium.com.

## About Hexium

## Company Overview
- **One-liner**: Hexium is modernizing isotope enrichment technology using Atomic Vapor Laser Isotope Separation (AVLIS) to produce critical isotopes for advanced nuclear energy, fusion, and medical applications, starting with lithium-6 and lithium-7.
- **Entity Type**: Private (Seed stage)
- **Headquarters**: Austin, Texas, United States
- **Founded**: 2023
- **Founders**: Charlie Jarrott (Co-Founder & CEO), Martin Griswold (CTO & Co-Founder)

## Core Business
- **Primary industry**: Advanced Manufacturing / Nuclear Energy / Isotope Enrichment
- **Target customers**: Advanced fission and fusion reactor developers, nuclear medicine producers, and industrial isotope users (B2B)
- **Mission statement**: Enable the nuclear technologies that will power a cleaner, safer, more resilient future.

## Products & Services
- **AVLIS Technology Platform**: A reinvented form of Atomic Vapor Laser Isotope Separation that uses laser-driven ionization and electric sorting to separate isotopes with unmatched precision. The process eliminates centrifuges and chemicals, produces no hazardous waste, and has the smallest commercial-scale footprint in the industry.
- **Lithium-6 (Li-6) Enrichment**: Production of lithium-6, a critical isotope for tritium breeding in fusion reactors and advanced fission systems.
- **Lithium-7 (Li-7) Enrichment**: Production of lithium-7, used as a pH control agent in pressurized water nuclear reactors and for other industrial applications.
- **Future Isotope Production**: The AVLIS platform is adaptable to produce other globally bottlenecked isotopes for clean energy, nuclear medicine, and advanced industrial applications.

## Market Standing
- **Valuation/Market Cap**: Not disclosed (Private company)
- **Total Funding**: USD $33.0 million (as of 2026)
- **Funding History**:
  - Seed Round (2024-07-01): USD $8.0M (led by MaC Venture Capital, Refactor)
  - Debt Financing (2025-04-01): USD $2.5M
  - Seed Round (2025-04-01): USD $9.5M (6 investors)
  - Funding Round (2025-08-21): USD $13.0M
  - Loan (2026): USD $4.0M
- **Notable Investors**: MaC Venture Capital, Refactor Capital, R7, Overture VC, Julian Capital, Humba Ventures, and others
- **Key Partners**: Lawrence Livermore National Laboratory, TerraPower, Oklo Inc., MPR Associates, Inc.
- **Growth Signals**: 
  - Headcount growth of +88.9% year-over-year (now 12 employees)
  - Active collaboration with top national lab (LLNL) and leading advanced nuclear companies
  - With over $2B invested by the Department of Energy, the underlying AVLIS technology has been de-risked at pilot scale

## Competitive Advantages
- **Proven, De-Risked Technology**: The AVLIS approach was developed and validated at pilot scale with over $2B in DOE investment, now being modernized for industrial deployment.
- **Unmatched Precision**: Industry-leading selectivity enables single-pass production of materials at both high purity and lower enrichment levels compared to traditional methods.
- **No Centrifuges or Chemicals**: Eliminates complex mechanical and chemical separation methods, avoids costly separation agents, and produces no hazardous waste — a clean and scalable approach.
- **Small Footprint, Quick Scalability**: The smallest commercial-scale footprint in the industry that can be rapidly scaled to meet growing demand.
- **Domestic Supply Chain Focus**: Building a reliable, secure domestic supply of critical isotopes for US energy and medical independence.
- **Patent-Pending Technology**: Optimizes production output while leveraging existing supply chain infrastructure and modern laser designs.

## Strategic Focus
- Industrial-scale deployment of AVLIS technology for lithium-6 and lithium-7 production to fuel the nuclear renaissance
- Expanding isotope production capabilities to other bottlenecked isotopes for energy, medicine, and industry
- Scaling the team with scientists and engineers across laser physics, plasma physics, nuclear engineering, electrical engineering, and manufacturing
- Building the domestic supply chain for critical isotopes used in advanced fission and fusion reactors

## Why Work Here
- **Hands-On Lab Culture**: Most roles are on-site in Austin, TX, where teams work directly with real hardware — lasers, optics, electronics, vacuum systems, and plasma sources. Engineers see their designs come to life in the lab.
- **Small Team, Big Ownership**: With only 12 employees (+88.9% YoY growth), team members work closely with founders and technical leaders. Ideas and contributions directly shape the technology and roadmap.
- **Mission-Driven Work**: Everything the company does supports next-generation fission, fusion, and scientific innovation — with long-term impact on clean energy and research.
- **Room to Grow**: As the company scales, there are significant opportunities to take on new responsibilities, lead projects, and grow with the organization.
- **Cross-Disciplinary Collaboration**: Engineers, physicists, chemists, and operations staff work side-by-side to solve complex, interdisciplinary problems.
- **Culture Highlights**: Weekly team lunches, regular opportunities to share progress and ideas, flexible work hours.
- **Compensation**: Competitive compensation including equity, performance bonus, paid time off, 401(k) matching, medical/dental/vision benefits, HSA and FSA options.
- **Office Policy**: On-site in Austin, TX (hands-on hardware roles require lab presence)
- **Tech Stack**: LabVIEW, CODESYS, SolidWorks, and other tools relevant to laser systems and automation

## Sources
1. [hexium.com](https://www.hexium.com/)
2. [hexium.com/careers](https://www.hexium.com/careers)
3. [linkedin.com/company/hexiuminc](https://www.linkedin.com/company/hexiuminc)
4. [job-boards.greenhouse.io/hexium](https://job-boards.greenhouse.io/hexium)
5. [cbinsights.com/company/hexium](https://www.cbinsights.com/company/hexium)

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