It is proved that some compositions of independent magnetic field scalar polentials, which are expressed by spherical coordinates, construct the toroidal closed magnetic surfaces and have characteristic of average minimum B toroidal field. It is noticed that they don't need any conductors which sink in plasma. The equations of the magnetic surfaces, V', the rotational transform angle on the magnetic axis of these fields are calculated by the averaged method.
The dispersion relation for the drift cyclotron instability is modified to include the effects of trapped particles. The modification improves the agreement between the theory and the experimental observation in the Gulf General Atomic octopole device.
Toroidal configurations with a quadrupole-like separatrix are discussed. The configurations are produced by superposing a quadrupole field and a pair of radial transform fields on a toroidal field. They may have magnetic shears close to unity. The radial transform fields are produced by planer spiral coils which may be fabricated much more accurately than toroidal-helical coils and also leave the side of the torus accessible.