TCV — Tokamak à Configuration Variable — is the shaping-focused 📝Tokamak operated by the Swiss Plasma Center at EPFL in Lausanne, built to produce a wider range of 📝plasma cross-sections than any other machine without changing hardware.
The name is the design. TCV's vacuum vessel is unusually tall and narrow and is surrounded by sixteen independently powered shaping coils, so elongation, triangularity, and 📝divertor topology become knobs turned between shots rather than rebuilds. Its published parameters are modest — major radius 0.88 metres, minor radius 0.25, 📝toroidal field 1.43 📝tesla, 📝plasma current up to 1.2 megaamperes, about two seconds of pulse — and beside the point. Heating is almost entirely by 📝electron cyclotron resonance power from a bank of 📝gyrotrons, with divertor baffles added for the 2019–20 campaign to extend the configurational range further.
Flexibility plus a fast shot cycle makes TCV the machine where control ideas get tested cheaply. It has been a principal venue for machine-learning plasma control, and for cross-machine turbulence validation: the TCV-X21 reference case, a carefully specified boundary scenario, is used to benchmark edge simulation codes against measured filament properties. A machine whose value lies in what can be varied rather than what can be reached sits at the opposite pole from high-field devices such as 📝Alcator C-Mod, and the two answer different questions.