In electrostatic tandem charged particle accelerators, gas stripping targets are used to convert negative ions into positive ones. Partial ionization of the gas by ions leads to the formation of an undesirable beam of stripping gas ions in the accelerating channels. In this work, the current of a beam of argon ions produced in a tandem accelerator with vacuum insulation was measured by mass spectroscopy. It is shown that the current of argon ions is 2000 times smaller than the current of the proton beam. The reliability of the measurements is provided by visualization of an argon ion beam on the surface of a lithium target and is also confirmed by an experiment with increased gas injection and an estimate of the possible contribution of the proton beam. It is shown that such a small value of the argon ion current does not pose a danger either as a source of additional heating of a lithium target, or as an additional load of a high-voltage power supply, and therefore does not require the previously proposed means for its suppression.