In this work, a charge particle beam transport in a corona discharge ion source with a thin diaphragm focusing system taking into account the gas-dynamic flow in the vicinity of the nozzle has been studied experimentally. The space of influence of the gas-dynamic flow on the ion transport in the vicinity of the nozzle was shown not to exceed two nozzle diameters. 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. Using the focusing system allowed one to triple the current entering the collector and to raise the sum of currents entering the nozzle and collector by an order of magnitude.