A compact 6‐lens electrostatic quadrupole lens system in conjunction with a short, single einzel lens section has been developed with the aim of transporting a 30 mA, 35 kV H−beam [normalized beam brightness of about 1011A/(m‐rad)2] over a length of about 30 cm and focusing it into an RFQ. The effect of a neutral background gas on the measurements of the beam from the ion source is studied in order to evaluate reliably the input beam parameters for the lens design. The beam dynamics calculations have been made using simulation codes for typical H−beam parameters from two different ion sources; a magnetron type and a volume source type. The simulation results show a relatively modest emittance growth, that is within about 50–60% even in the case of an input beam with very small beam radius (1.1 mm) and very large divergence (72 mrad).