Abstract <p>We presented the results of the two-dimensional kinetic simulation of the vacuum gap commutation stage accompanying the cathode plasma jet expansion. It was shown that depending on the value of the current passed through the vacuum gap, two different commutation regimes could exist, namely, the stable commutation regime and the unstable quasi-periodic regime. Within the stable regime, the spark stage of the vacuum breakdown passed into a quasi-stationary arc. On the contrary, within the unstable regime, passing into the arc was not observed. The cause of the unstable regime occurrence was the current instability developing in the plasma. The instability led to a rapid partial decay of the cathode jet plasma. In addition, it was shown that the plasma instability arising contributed to the broadening of the energy distribution of the ions that reached the anode and the distribution maximum shift.</p>