For heating the plasma of HT‐6 Tokamak we have developed a multiampere ion source, which is able to provide positive ion current (pulsed 20 A). In this article we briefly introduce two significant studies we made while developing the big multicusp ion source. One is optimizing the pulse width of preadmission to obtain a uniform pulsed ion current; the other is making an insulating ring of two sorts of material to enhance the electrical character of the ring. Both of them made contributions to the extracted ion current.