About Commonwealth Fusion Systems: Commonwealth Fusion Systems is on a mission to deliver the urgent transition to fusion energy. Combining decades of research, top talent, and new technologies, we’re designing and building commercially viable fusion power plants. And we're working with policymakers, suppliers, and many others to build the energy industry of the future. We’re in the best position to make it happen. Since 2018, we’ve raised $4 billion of capital, making us the largest and leading fusion company in the world. Now we’re looking for more thinkers, doers, builders, and makers to join us. People who’ll bring new perspectives, solve tough problems, and thrive as part of a team. If that’s you and this role fits, we want to hear from you. Join the power movement as a Senior Mechanical Engineer As a Senior Mechanical Engineer on the Assembly Team at CFS, you design, develop, and manage fabrication of the wide variety of unique tooling needed for the successful assembly and integration of the SPARC tokamak device. This will entail the development of the overall concept, engineering, and use strategy of each tool assembly, and of the assembly step that the tool will facilitate. You will work closely and collaborate with the system teams to find the most efficient, creative, cost-effective, and safest way to manipulate, guide, and integrate each part of the larger tokamak system, design and build the tools needed, then finally write work-instruction packets that guide the use of the tool at the time of assembly. You will use your expertise on our most complex, largest, and most critical tools and manipulations, ensuring completion of the most challenging parts of SPARC assembly. You will guide and create how the giant parts of this multi-million pound “swiss-watch” come together, and the mega-tools to do it! This work is conducted within a multi-disciplinary team of physicists and engineers as part of collaborative sponsored research projects at the MIT Plasma Science and Fusion Center and within CFS.