An experiment on a pulsed cold cathode PIG ion source of modified Keller-type was investigated. The source was designed for a Cockcroft-Walton accelerator for a pulsed neutron generation. Ion current of 10 mA was extracted from deuterium discharge at the discharge pressure of 10^-2 Torr for the discharge current of 0.5 A and the extraction voltage of 20 kV. The ion energy spectra were observed in detail, and it was observed that an energy spread was narrower than that which was observed by Nagy. The voltage to maintain the discharge rises day by day, but change in the energy spectra was small. This new designed ion source is convenient and more suitable for practical use.