Pegasus Toroidal Experiment

The Pegasus Toroidal Experiment is a plasma confinement experiment relevant to fusion power production, run by the Department of Engineering Physics of the University of Wisconsin–Madison. It is a spherical tokamak, a very low-aspect-ratio version of the tokamak configuration, i.e. the minor radius of the torus is comparable to the major radius.

Pegasus Toroidal Experiment
Pegasus Toroidal Experiment (6140926094).jpg
Device TypeSpherical tokamak
LocationMadison, Wisconsin, US
AffiliationUniversity of Wisconsin–Madison
Technical specifications
Major Radius45 cm (18 in)
Minor Radius40 cm (16 in)
WebsitePegasus Toroidal Experiment webpage

Local Helicity InjectionEdit

Pegasus is used to study start up of spherical tokamaks using local helicity injection.[1][2]


Pegasus is being upgraded in 2019 (eg. by removal of the central solenoid) to build the Unified Reduced Non-Inductive Assessment (URANIA) experiment. This will study plasma startup using transient coaxial helicity injection (CHI).[2][1]

The max toroidal field is being increased from 0.15 T to 0.6 T, and the pulse duration from 25 to 100 ms.[3]