The experimentally measured modulation characteristics of a planar Cs–Ba plasma switch (tacitron) are presented and discussed. Tests are performed that focus on characterizing the operation capabilities of a planar Cs–Ba tacitron. Results show that the operation characteristics of the device are independent of geometry (cylindrical or planar). The forward voltage drop decreases as either the grid‐collector (GC) gap size and/or the Cs pressure increases. Also, stable current modulation is easier to sustain when the grid is placed closer to the collector, at the expense of increasing the forward voltage drop across the device.