On New Vacua of non-Supersymmetric Strings

We describe two new types of vacua for ten-dimensional string models without supersymmetry, in which dilaton potentials are compensated by constant electric or magnetic fields. These arise from $\alpha '$ corrections to the equations of motion, and we comment on the reliability of this expansion. We identify explicitly unstable singlet scalar perturbations in the orientifold vacua, and we argue that in both cases additional instabilities are induced by non-abelian couplings.