Transient coaxial helical injection (CHI) allows a tokamak to be started without a central solenoid. This seems to be rather interesting and promising.
https://www.pppl.gov/news/2019/04/ready ... -reactions
Transient coaxial helical injection (CHI)
Re: Transient coaxial helical injection (CHI)
Great for spherical tokamak designs like the ones by Tokamak Energy.