Engineering hardware for extreme scales
Andrew Bezdjian, Senior Engineering Manager
Fusion requires engineering at extreme physical limits. To combine atoms, we need to heat fuel to over 100 million degrees and compress it with forces similar to multiple rockets lifting off, all in the blink of an eye. Hardware that can achieve this must operate at the edge of what’s currently possible. Helion’s engineering team bridges the gap between extreme physics and real, practical machines that operate repeatably and reliably to recreate these environments.
Fusion conditions as a design requirement
Fusion relies on fuel that is extremely hot, extremely dense, and held together long enough to react. A magnetic field provides a single, elegant way to satisfy all three requirements, but only if that field is both very strong and generated quickly. Pulling massive currents through electromagnets on microsecond timescales allows us to do this, but it also creates extraordinary mechanical challenges. Each magnetic coil experiences internal forces of millions of pounds, and the coils exert enormous forces on one another. Every part of the mechanical design must account for these stresses and loads.
Selecting the right material throughout the mechanical design requires navigating trade-offs in things like conductivity, strength, thermal behavior, and manufacturability. In turn, we rigorously explore our design space to find the right balance for Helion’s ideal operating regime.
Because fusion hardware operates at strain rates and stress levels that are rare in other industries, material data for these conditions is often nonexistent. Helion’s solution is to generate the data ourselves. We run simple coupon-scale tests to probe material behavior, then ground our models by conducting tests on full scale magnets before running those conditions on the machine. A network of high-speed mechanical diagnostics measures strain, deflection, and acceleration, and these measurements feed into detailed finite-element analysis (FEA) simulations. This enables consistent and predictive mechanical and electromagnetic models that evolve alongside our hardware development.
Even though analogies exist, like comparing our loads to the forces seen during rocket launches or deep in the ocean, our loads increase far more rapidly. That makes the dynamic structural and thermal loading much more important than static or steady state analysis.
Controlling the time domain
Precise timing is central to controlling the fuel we heat into field-reversed configuration (FRC) plasmas. Magnets must activate in sequence, shaping and accelerating the plasma with nanosecond-level coordination. To accomplish this, we use communication at the speed of light through thousands of carefully length-planned optical fibers, and we verify timing using measurements taken with and without plasmas. The electronics involved are chosen to avoid hysteresis so that they behave consistently from pulse to pulse.
Because no measurement can ever be exact, we focus not on “perfect” synchronization but on understanding how much timing variation the integrated system can tolerate. When a magnet activates over microseconds, it produces mechanical responses based on the speed of sound in the material. These responses behave like shock waves propagating through the structure. A slight timing mismatch can cause shocks to overlap or reinforce each other, producing dangerously high localized stresses.
We model these interactions using a combination of mechanical and electromagnetic finite-element tools. Understanding how shocks move through the hardware determines which mismatches are acceptable and where design changes or dampening elements must be added. At this point, material properties re-enter the picture again: the speed of sound, damping behavior, and resonance of each component influence how shock waves propagate. Designing for fusion requires coordinating all these dynamic properties into a single, cohesive system.
In addition to thorough FEA models, we will also perform full-scale development, qualification and acceptance testing for any high-risk hardware before it gets on a machine. We leverage these high energy (but lower risk) tests to further anchor our analytical models and to probe for weak points in our mechanical structure or fundamental understanding of the problem. Testing hardware is another huge part of what our engineering teams plan and work towards, and we are always working on new and novel ways to buy down hardware risk.
There is no book for fusion hardware (yet)
Fusion pushes beyond long-established engineering fields. Some of what we need can be adapted from aerospace, nuclear fission, car-crash mechanics, and high-energy physics, but much of it has to be created from first-principles thinking. Progress comes from designing, building, testing, and iterating. This approach has enabled Helion to build seven generations of machines rapidly, each one informed by the data gaps we have closed ourselves.
Going further means pushing all fronts at once: developing stronger, radiation tolerant and more specialized materials to support higher magnetic fields, creating even more precise timing systems using novel electronics, and incorporating advances from external research when they appear. But much of the necessary innovation will come from Helion directly, because many of these challenges have never been encountered before.
The scale of the engineering challenge will only increase as we accelerate our build rate from one machine every few years to annual production, then weekly, and eventually daily. Engineering for fusion means engineering at extreme scales across the physical, temporal, and organizational; we’re doing so by continually expanding the boundaries of what the field knows how to do.