Senior Power Systems Engineer Jobs in California

Castelion is moving incredibly fast to develop and deliver advanced defense systems at a time when execution matters more than ever. We believe focus and technical excellence are decisive advantages - and we are building a team that can deliver real capability, not just concepts.

This is a rare opportunity to join at an early stage, where your work will directly shape critical systems, influence major technical decisions, and have immediate, real-world impact.

We are seeking a Senior Power Electronics Engineer to develop and integrate advanced electrical power systems for Castelion's long-range hypersonic strike vehicles. This role is critical to ensuring reliable power generation, storage, and distribution across mission-critical avionics and vehicle subsystems. You will work hands‑on with multidisciplinary engineering teams to design, analyze, test, and validate power electronics hardware in a fast-paced, hardware-driven environment.

• Design and develop power electronics systems including battery architectures, power conversion, and distribution for high-performance flight vehicles
• Lead the design and optimization of power controllers and power management systems to ensure stable, efficient operation across all mission phases
• Develop and analyze battery systems, including selection, packaging, thermal considerations, and safety mechanisms for demanding environments
• Work closely with avionics, GNC, and flight software teams to ensure seamless integration of power systems with vehicle subsystems
• Conduct circuit-level and system-level modeling and simulation to evaluate performance, efficiency, and reliability under dynamic conditionsSupport hardware bring-up, integration, and test campaigns, including troubleshooting and root cause analysis
• Define and execute qualification and flight test plans, translating results into system-level improvements
• Mentor junior engineers and contribute to best practices in power electronics design
• Partner closely with program leadership to make technical trades aligned with mission success

• Bachelor's, Master's, or PhD in Electrical Engineering or related field
• 5+ years of experience in power electronics design, analysis, and validation for aerospace, defense, or other high-reliability systems
• Strong background in battery systems, power conversion (DC-DC), and power distribution architectures
• Experience designing power controllers and power management systems for embedded or avionics applications
• Proficiency in circuit design, simulation, and analysis tools (e.g., SPICE, MATLAB/Simulink, or equivalent)
• Experience with hardware bring-up, test, and troubleshooting in a lab or flight hardware environment
• Familiarity with thermal management, EMI/EMC considerations, and ruggedized electronics design
• Strong problem-solving mindset, thriving in a fast-paced, hardware-rich, high flight cadence environment

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. Duties, responsibilities, and activities may change at any time with or without notice.

All full‑time employees are granted meaningful long-term equity, sharing in the company's significant growth trajectory. We offer four (4) weeks of paid time off, ten (10) company‑paid holidays, and comprehensive health benefits— including 100% employee‑covered medical and strong dependent coverage, along with dental and vision plans. We also provide paid parental leave to support growing families, a $100 monthly fitness stipend to promote health and performance, and onsite EV charging for convenience. In addition, employees enjoy perks like catered meals, company‑covered food during high‑demand periods, and a fully stocked kitchen to stay fueled throughout the day.

While this position does not currently require a U.S government‑issued security clearance, it may in the near future. Therefore, the ability to obtain and maintain a U.S. government‑issued security clearance is required. U.S. citizenship is required, as only U.S. citizens are eligible for a security clearance.

Employment with Castelion is governed on the basis of competence and qualifications and will not be influenced in any manner by race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, sexual orientation, gender identity, marital status, mental or physical disability or any other legally protected status.