In this work, a charged particle beam transport in an ion source with a corona discharge, the source being equipped with a focusing system based on thin diaphragms in the standing gas and at atmospheric pressure, has been studied experimentally. The efficiency of the ion beam transportation through the focusing system was shown to depend on the distance between the corona needle and the diaphragm system, on the potential difference between the diaphragms of the focusing system and on the value of the corona discharge current. The results of comparing the efficiency of the ion beam transport in the ion source with using the focusing system and without it are presented. The use of the focusing system allowed to increase several times the current entering the collector through the diaphragm of the smallest diameter, and to raise the current entering the plane of this diaphragm by an order of magnitude.