  Plasma toroidal metric singularities in helical devices and tokamaks, giving
rise to magnetic surfaces inside the plasma devices are investigated in two
cases. In the first we consider the case of a rotational plasma on an helical
device with circular cross-section and dissipation. In this case singularities
are shown to place a Ricci scalar curvature bound on the radius of the surface
where the Ricci scalar is the contraction of the constant Riemannian curvature
tensor of magnetic surfaces. An upper bound on the initial magnetic field in
terms of the Ricci scalar is obtained. This last bound may be useful in the
engineering construction of plasma devices in laboratories. The normal poloidal
drift velocity is also computed. In the second case a toroidal metric is used
to show that there is a relation between singularities and the type of tearing
instabilities considered in the tokamak. Besides, in this case Ricci
collineations and Killing symmetries are computed.The pressure is computed by
applying these constraints to the pressure equations in tokamaks.
