Analog of the Anderson Theorem for the Polar Phase of Liquid 3He in a Nematic Aerogel

The effect of an aerogel with parallel fibers on the temperatures of He-3 transition to superfluid phases differing in the l(z) projections of the orbital angular momentum on the directions of the fibers is considered. It is shown that at the specular reflection of Fermi excitations of liquid He-3 from the fibers, the temperature of transition to the polar phase corresponding to l(Z) = 0 remains the same as the temperature of transition to any phase with orbital angular momentum l = 1 in the absence of the aerogel. The temperature of transition into phases with l(z) = +/- 1 turns out to be lower, and there appears to be a finite temperature interval in which only the polar phase is stable. This interval has been determined. The effect of the magnetic (exchange) scattering of Fermi excitations at adsorbed He-3 atoms on the temperature of transition of He-3 to the superfluid state has been estimated.