In their meetings in December 2024, the Swiss Parliament gave the green light for the release of funds for projects proposed within the Swiss Roadmap for Research Infrastructure 2023 – among them the Swiss Fusion Hub, a substantial upgrade of SPC’s infrastructure. This marks the final step of a multi-stage selection process, in which the Swiss Fusion Hub proposal was awarded with a financial support of 12.5 million francs for the period from 2025-2028, in order the implement the infrastructure upgrades described in the following.
- TCV divertor upgrade
We are now officially starting the next major upgrade of TCV, centered around the implementation of a tightly-baffled, long-legged divertor (TBLLD). This new divertor configuration combines key features that have previously been shown on TCV to strongly mitigate the heat fluxes to the wall and facilitate access to a detached divertor, namely strong baffling and a long divertor leg. At the same time, the TBLLD minimizes the engineering complexity in view of a possible future reactor implementation. An initial design for the first phase of this upgrade has already been elaborated, involving 96, 35 cm long graphite bars to be installed on the TCV floor. The full design, construction, and scientific exploitation of this divertor will be an institute-wide adventure, involving a broad range of expertise – and very skilled and flexible persons for its installation!
- TCV diagnostics
An upgrade to the diagnostics suite on TCV will accompany the TBLLD, enhancing our ability to evaluate this innovative divertor design and deepen our understanding of divertor physics. Key measurements, such as neutral pressure along the slot, will shed light on neutral baffling, while classic tools like Langmuir probes and the divertor reciprocating divertor probe array will track particle fluxes within the TBLLD. A major challenge is the limited visibility of surfaces inside the baffles, which complicates heat flux analysis typically conducted with infrared cameras.
To overcome this, we are developing a novel “surface eroding thermocouple” diagnostic, capable of rapid heat flux measurements within the baffled structure. Together with TCV’s advanced systems, including foil bolometers, this suite will deliver unprecedented insights into the physics driving the TBLLD.
- Heating upgrade
The Swiss Fusion Hub proposal also includes a fourth, 1MW dual-frequency gyrotron to further extend the generous TCV second- and third harmonic electron cyclotron resonance and neutral beam heating mix. This new gyrotron will be complemented by upgraded top- and lateral-launch antennas, a new Pulsed-Switch Modulation high-voltage power supply to reduce ripple and noise on the gyrotron accelerating voltage, and novel fast anode-power supplies, to be developed in-house and providing a faster rise time and improved power modulation capabilities.
This heating upgrade will allow testing and optimizing the TBLLD in extreme conditions, tailoring core (density) profiles and power levels in the ITER baseline scenario and in negative triangularity plasmas in view of DEMO, and enhancing TCV’s actuator set for real-time control.
- EDIPO2
Over the past two decades, all major superconducting fusion facilities in the world, including ITER, JT60-SA, SPARC, BEST, CFETR, DTT, and the EU DEMO, have qualified their superconductors in the SULTAN test facility at SPC-Villigen. The growing demand for higher field and higher current conductors—partly driven by the development of High Temperature Superconductors —requires testing capabilities beyond SULTAN’s current limits (B≤11 T, I≤100 kA).
EDIPO2 will enhance our testing capabilities at SPC closer to the needs for the new generation of superconducting samples. The improvements include a new magnet generating a background field of 15 T, an enlarged aperture, and a new superconducting transformer designed to test samples beyond 100 kA. EDIPO2 will ensure that SPC retains its leading role in testing superconductors for the global fusion community.
In the last few years, the Applied Superconductivity Group has elaborated on the conceptual design and technical specifications of EDIPO2. With the decision on the Swiss Fusion Hub, EDIPO2 enters into the engineering phase, and we will soon sign contracts with the industry to purchase the required superconducting strand, to make a two-stage cable out of it, and to produce the upgraded magnet. The insertion of the magnet into the facility and final commissioning is foreseen in 2028.