Helical Fusion Announces High-Temperature Superconductor Breakthrough
Back to some fusion energy coverage 😊! Earlier today, Helical Fusion announced a milestone by successfully completing a critical performance test of their high-temperature superconductor (HTS) coil for their Helical Stellarator. The Fusion Report is sharing the press release, as well as a summary of the test, and why it is important for Helical’s efforts, which also kicked off the construction of their integrated demonstration device, the Helix HARUKA.
Just for a refresher, Helical Fusion is building a helical stellarator, a rendering of which is shown to the right. This follows Helical’s raise in July of this year of a Series A fund of JPY 2.3B (roughly $15M US), increasing their total funding to JPY 5.2B ($35M US). Their fusion architecture builds upon the successes of Japan’s National Institute for Fusion Science (NIFS) and their Large Helical Device (LHD) stellarator. Unlike tokamaks, which use a “donut” toroidal approach to confine the fusing plasma, stellarators utilize a twisting magnetic field (see how the magnets in the illustration above are twisted around the plasma core) to mitigate some plasma stability issues. It is a testament to the idea that there is not just one answer to how to best achieve fusion, and invokes a (paraphrasing of) a quote from Southern Nuclear Operating Company executive John Williams, who said in a recent webinar:
“There’s a great quote by a French economist that says the French have 90 kinds of cheese and one kind of reactor (in the case of fusion, the tokamak) and the U.S. (or world in the case of fusion) has 90 kinds of reactors. And it’s very true.”
While John was admittedly talking about nuclear fission reactors (hence the paraphrasing), the same could easily be applied to (and is perhaps even more true for) fusion energy machines, which is good – the more approaches, the more shots on goal.
Helical Fusion’s Magnetic Breakthrough (Hold the Syrup!)
As you can imagine, one of the critical requirements for any reactor that utilizes magnetic confinement fusion (MCF) is for the magnets (in most cases, superconducting magnets) to be able to achieve stable operation under the high magnetic fields in a fusion machine. While most MCF machines utilize magnets built by wrapping HTS tape into large structures, Helical Fusion’s magnets are made up of groups of HTS wires which are wound into cables, as shown to the right. This approach allows these magnets to be easily twisted into arbitrary curved shapes, which is critical for stellarator operation.
The testing that Helical’s HTS magnets recently underwent put a coil of these magnets (known as a “double pancake coil”) into the NIFS large-diameter high-field testing facility, where the coil was subjected to a 7-tesla external magnetic field. The coil, which was kept at a temperature of 15 degrees Kelvin (-258 degrees C, -433 degrees F), was able to achieve a stable current flow of 40kA for an extended period of time. This milestone, which replicated the conditions that the HTS magnets would be subjected to in a production helical stellarator, showed the viability of Helical Fusion’s approach to developing HTS magnets for their production fusion machine.
Moving From Subsystems to Full Integration
With this successful test of their HTS magnets, Helical Fusion is now undertaking the construction of their integration demonstration device, the Helix HARUKA. HARUKA combines a number of technologies with Helical Fusion’s HTS magnetics, including their thermal blanket and diverter designs, into a system that can demonstrate these systems together before the end of this decade. Successful operation of HARUKA will lead to construction of the Helix KANATA, Helical Fusion’s commercially viable fusion power plant, and the next step in their corporate roadmap. Helix KANATA is expected to be operational in the 2030s timeframe, and will act as the prototype for Helical’s mass-produced fusion machines for commercial power plant deployment.
