On criteria of polarization conservation in accelerators with 'Sibirian snakes'

Restrictions for beam emittance and for irregularity of magnetic structure necessary to keep beam polarization in accelerators with 'Sibirian snakes' are formulated. Variation tendencies of thses criteria with increase of maximal energies and accelerator dimensions to high energies are considered. Conclusion is made, that acceleration of polarized particles up to maximal energies in operating accelerators and those under development is a real one