A novel type of polarized3He ion source based on “electron pumping” was recently proposed. This ion source requires multiple electron capture and stripping collisions of3He+ions with polarized alkali atoms under a strong magnetic field (2–3 T). Since these processes may induce a serious increase in the emittance and reduction of polarized beam intensity, we investigated them in detail by using the Monte Carlo simulation. It was found that there is (1) increase in the emittance results not from angular broadening but from a beam size enlargement, (2) the phenomena under magnetic fieldBare simplified by a collisionless phenomenon under a weaker magnetic field (effective magnetic field)Beffdefined byBeff≃(&lgr;+0/(&lgr;+0+&lgr;0+))B,where&lgr;+0and&lgr;0+are mean free paths for3He+ions and3He0atoms traveling in the alkali vapor. ©1998 American Institute of Physics.