Welcome
The Helically Symmetric eXperiment (HSX) is an optimized stellarator operated by the College of Engineering at UW–Madison. Three-dimensional shaped coils are arranged in a torus-like configuration to produce a 1 Tesla magnetic field that confines a plasma with temperatures higher than 10 million degrees C. The goal of the experiment is to contribute to the physics basis of a future power plant which produces energy by fusing Hydrogen isotopes to Helium.
Latest News
11/3/26:
The HSX group from UW–Madison had a strong showing at this year’s APS Division of Plasma Physics meeting in Chicago, IL. Scientists, current and past graduate students, and undergraduates were all represented.
What is quasi-helical symmetry?
HSX is the only device in the world that has a magnetic field structure described as Quasi-Helically Symmetric (QHS) where high and low-field regions of the magnetic field wrap helically around the toroidal direction of the device (see picture above) such that a plasma particle “sees” a nearly symmetric path as it orbits. This “optimized” geometry solves many of the problems inherent in conventional stellarators and provides excellent plasma confinement properties.
Research
Plasma physics research at HSX focuses on studies of turbulent transport, the generation and damping of flows in the quasi-symmetric 3-D magnetic field geometry, as well as the development and testing of diagnostics for characterization of fusion-relevant plasmas.
Video showing the perturbed electrostatic potential inside HSX, as simulated by the turbulence simulation code GENE.
Device Parameters
| Major Radius (machine center to Plasma center): | 1.20 meters |
| Average Plasma Minor Radius: | 0.12 meters |
| Aspect Ratio (Major Radius/Plasma Radius): | 10 |
| Plasma Volume: | 0.44 cubic meters |
| Number of Field Periods (symmetry around torus): | 4 |
| Rotational Transform on axis: | 1.05 |
