Superfluid Phases of 3He in Aerogel

Within a phenomenological approach a criterion for a choice of forms of the order parameter of the superfluid phases of 3He in aerogel in a vicinity of the transition temperature is derived. The order parameter of bulk B-phase of 3He meets this criterion and that of the bulk A-phase doesn`t. A class of order parameters of Equal Spin Pairing (ESP) type meeting the derived criterion is discussed. Order parameters belonging to this class are proposed as candidates for the observed A-like superfluid phase of liquid 3He in aerogel. Effect of magnetic field on the order parameters of this class is considered.