  The effect of the Pauli exclusion principle on double ionization of He atoms
by strong, linearly polarized laser pulses is analyzed. We show that correlated
electron escape, with electron momenta symmetric with respect to the field
polarization axis, is suppressed if atoms are initially prepared in the
metastable state 3S. The effect is a consequence of selection rules for the
transition to the appropriate outgoing two-electron states. We illustrate the
suppression in numerical calculations of electron and ion momentum
distributions within a reduced dimensionality model.
