48 tons of steel: Half the heart of SPARC fusion machine arri

This is really exciting. We actually have the first half of our vacuum vessel that's just arrived. The vacuum vessel is really the heart of SPARC. The plasma is contained inside of this vacuum vessel and what the vacuum vessel does is it evacuates all of the air outside of the vessel because even though this plasma is operating in extreme conditions, it's at a hundred million degrees, it's a very hot thing, you could actually extinguish it if you blew a breath of air on it. So the vacuum vessel is a chamber that protects the plasma from all of the air that is outside and creates an environment kind of like outer space where the stars live. We were able to take a lot of lessons learned from the other 150 tokamaks that have been built around the world in designing our vacuum vessel. So a crazy thing about this vacuum vessel is that we actually fabricated it not in two halves but as one piece and then we cut it in half. And you might ask why did we do that? It seems kind of a weird way to build something but it actually has to do with the geometry of how you build the machine. So the vacuum vessel lives inside of the TF magnets. We have those 18 magnets that form a ring and inside that ring is the vacuum vessel. But if you think about it geometrically there's kind of like an interlocking rings problem and you have to get one inside of the other. And so what we do is we put the machine together in halves. Behind me there's two separate tables that will have nine of the TF magnets on one and nine of the TF magnets on the other. And we're actually going to rotate in each half of the vacuum vessel into those nine TFs and then move the whole thing together and then re-weld the vacuum vessel closed once it's inside of that configuration. The vacuum vessel was one of the earliest things we started designing for Spark. So when I joined three and a half years ago we had a design and we were just about to start to procure the raw material that we wanted to make it out of. And that's where the materials and processing team jumped in to make sure we could work with our designers, our quality and our supply chain teams to get the actual stock that we needed to start sending to our fabricator Italy to actually make this thing. So the vacuum vessel is made out of a grade of steel commonly referred to as XM-19. It's a high grade of austenitic stainless steel which means that it's very strong at both room and high temperatures. So we need to make sure it's strong when it's hot unlike a lot of the steels that we use for Spark which need to be strong when they're cold. And so this steel it's not super commonly used in the world but it's not something we had to invent ourselves. And we went through a lot of early hurdles in selecting the most appropriate welded material. One to make sure that we meet these magnetic requirements and two that they have the toughness and ductility that we need so the vessel will mechanically do its job once it's in operation. I've been working on planning for assembling all the components into the vacuum vessel half that you see behind me. So we have the east vessel half here and we assemble a bunch of diagnostic equipment inside as well as plasma phasing components so when we turn Spark on the plasma can hit up against tungsten tiles. I've been preparing for the vacuum vessel to arrive for about a year now so now that the vacuum vessel is here we can actually start putting parts inside of You can think of the diagnostic system as the nervous system of the machine so we install a bunch of sensors around the vacuum vessel and then they're going to send back signals to tell us how to run Spark better. All the sensors are routed underneath the plasma phasing components that we install afterwards. Even though this is a large component that has a lot of detailed machining features it's actually in the realm of things that we machine already today. That is one of the beauties of Spark is that we've been able to leverage so many supply chains that exist out in the world that do things that are almost like what we're doing on Spark but not quite and that's really important because if we want to get to scale we don't want to have to scale up an entirely new manufacturing and supply chain that will be just for fusion. We want to adapt as much as we can that exists in the world so that we can go as fast as possible. So this is a really cool moment this is almost like when you're watching a building being constructed the first thing that people do is they dig the foundation and there's a whole bunch of work that goes on you kind of look at and you're like this is just a hole in the ground like what's going on when all of a sudden like a building just sort of seems to materialize that's what it's going to look like in here and this room was empty for a while because we were doing a whole bunch of prep work but now this room is really starting to fill up and get denser and denser. Eventually this room is going to be like swarmed with people who are around all the different aspects of the machine bolting on pieces and putting things together and welding and grinding and doing all the operations to assemble Spark. There's been a lot going on in the background but now you can like visibly see the progress every single day which is super exciting.