Projects

Current amplification of 3.9 was achieved. Toroidal current of 90 kA.

Current amplification was greater than 3. Current amplification is an important quantity for spheromaks.

Proto S-1A (sometimes known as Proto S-1A/B) was a prototype of S-1 built at PPPL in 1980. Its parts were a scaled down version of the S-1 device, 1/6 of the size of the main device. It was made to demonstrate the viability of the spheromak concept. Proto S-1A had a 15cm major radius and 3cm minor radius flux core which contained a 3-turn poloidal flux coil and a 40-turn toroidal flux coil. The core was covered with a 3mm thick stainless steel enclosure that functioned as a vacuum vessel and helped to symmetrize the induced fields. Discharges were made using hydrogen, helium and argon with pressures around 20 to 50 mTorr. Proto S1-A was able to maintain its fully formed configuration for 12 μs. After Proto S-1A, another prototype was built: Proto S-1C

Proto S-1C was a prototype of S-1 built at PPPL. It was a bigger version of Proto S-1A and 1/3 of the size of S-1. It was used for impurity control studies.

The S-1 was a spheromak located at PPPL. Its main objective was to study confinement and MHD stability of the spheromak concept. It began operations in September 1983, after two operational prototypes were tested: Proto S-1A and Proto S-1C. During its operation, the toroidal plasma currents reached approximately 600 kA and maximum plasma electron temperatures up to 500 eV. The vacuum vessel was made of two stainless steel domes with a large viton seal between them. Its base pressure was around 10^-8 torr.

In 1987 S-1 was shut down for budgetary reasons. The studies of the effects of spheromak plasma compression could not be completed before the project ended.