Power Systems

PPPL’s tokamak experiments rely on magnetic confinement of high temperature plasmas using high performance pulsed water-cooled electromagnets. They must be controlled with great precision to generate and shape the plasma during an experimental pulse. Once a plasma is established, powerful heating systems are used to achieve the very high temperatures needed for fusion.

 Complex power supply systems comprised of AC/DC converters and other unique components are used to energize the magnets and heating systems at currents exceeding 100kA and voltages exceeding 100kV.  

The power demand of PPPL’s largest experiments is very high, but only during pulses lasting up to ~ 10 seconds during each plasma discharge. It is impractical to supply this level of power directly from the utility grid, so the pulsed power is supplied by motor-generators that store energy from the grid by slow acceleration between pulses. They then deliver the energy at a very high power level by rapid deceleration during a pulse. 

 PPPL’s largest electrical power system consists of a 138kV substation, 950MVA/4.5GJ motor-generator system, variable frequency 13.8kV AC distribution system, various AC/DC converter systems, various DC distribution systems, as well as all of the monitoring, control and protection devices required for operations. This system was originally installed[1] to power the Tokamak Fusion Test Reactor (TFTR) experiment in the 1980s but thanks to its flexible, modular design it has been adapted to serve other experiments including PPPL’s flagship experiment, the National Spherical Torus Experiment - Upgrade. Many features of its design have been adopted by the ITER project[2] now under construction in France.

[1] C. Neumeyer, “TFTR power conversion and plasma feedback systems,” Fusion Technology 1984. Proceedings of the Thirteenth Symposium on Fusion Technology, p. 919-25 vol. 2, 1984

2 C. Neumeyer, et al., “ITER power supply innovations and advances,” Proceedings of 2013 IEEE 25th Symposium on Fusion Engineering, SOFE 2013