Improving Negative Ion Beam Quality and Purity with a RF Quadrupole Cooler

Abstract

Abstract. When does a topological group G have a Hausdorff compactification bG with a remainder belonging to a given class of spaces? In this paper, we mainly improve some results of A.V. Arhangel'skiǐ and C. Liu's. Let G be a non-locally compact topological group and bG be a compactification of G. The following facts are established: (1) If bG \ G has a locally a point-countable p-metabase and π-character of bG \ G is countable, then G and bG are separable and metrizable; (2) If bG \ G has locally a δθ-base, then G and bG are separable and metrizable; (3) If bG \ G has locally a quasi-G δ -diagonal, then G and bG are separable and metrizable. Finally, we give a partial answer for a question, which was posed by C. Liu in [16].