LSP

The Levitated Spherator (LSP) was the first spherator built with a levitated internal ring at PPPL. LSP was similar to SP-3 in geometry but without the internal ring supports. The idea of levitating the ring instead of using mechanical supports was to increase the confinement time by eliminating the particle losses due to asymmetries caused by the supports in previous spherators.

It had a superconductive internal ring with a radius of 0,46 m and capable of transporting a 85 kA current, that was levitated with magnetic fields. To keep the superconductivity, the ring was filled with liquid helium to keep it cold. It used ECRH heating with 10ms pulses of 1kW 2.45 GHz microwaves and steady heating of 60 W 3.5 GHz microwaves, which produced temperatures up to 10 eV. LSP was also heated ohmically, reaching temperatures up to 100 eV. This device had an average magnetic field of 0.1 T. FM-1 was a larger version of this device.