- The Tokamak possesses desirable physics attributes for a fusion reactor based on its axisymmetric nature:
- Good single-particle confinement
- Can be designed for low aspect ratio
- Simple coil-set

- The lack of symmetry in the magnetic fields in
**conventional**stellarators results in large deviations of particle orbits from magnetic surfaces and direct loss orbits – enhanced low-collisionality transport and poor low-collisionality confinement

- Stellarator with helically symmetric field inherently possesses solutions to many problems currently being examined in tokamak research and in conventional stellarator research:
- Intrinsically steady-state devices
- No observed density limit
- No required plasma current for confinement
- |
| is independent of a helical-like angle variable**B** - Neoclassical transport is directly analogous to, and reduced, as compared to an equivalent axisymmetric system (Tokamak)
- 1/
`?`regime suppressed - No superbanana orbits
- No direct loss orbits
- Good collisionless alpha particle confinement

**HSX** is the only device in the world that has a magnetic field structure that has been termed Quasi-Helically Symmetric (QHS). Quasi-helically symmetric stellarators, to a good approximation, possess a direction of symmetry and are therefore topologically equivalent to a tokamak without plasma current. They achieve this near-symmetry by having virtually no toroidal curvature that a conventional toroidal device would have if it had an aspect ratio greater than 400.