Experimental investigation of current modulation in a planar Cs-Ba tacitron

The Cs-Ba tacitron is being considered as a switch, or as an inverter consisting of two switches operating in a push-pull mode, for power conditioning of low voltage/high current dc power sources operating in high radiation/high temperature environment, beyond the limits of semiconductor switches. This paper presents new experimental results delineating the effect of the various operating parameters on the grid potential needed for ignition, V/sub g//sup +/, and extinguishing, V/sub g//sup -/, during stable current modulation of a planar Cs-Ba tacitron. Parameters investigated are Cs pressure, emitter temperature, T/sub E/, discharge current, I/sub C/, and modulation frequency, f/sub g/. The value of V/sub g//sup +/, which is independent of T/sub E/, decreases as Cs pressure increases, but increases as either I/sub C/ or f/sub g/ increases. Increasing the emitter temperature from 1100-1200/spl deg/C only slightly decreases the forward voltage drop in the device by /spl sim/0.2 V. The value of |V/sub g//sup -/| increases with Cs pressure, decreases with increased T/sub E/, and is sensitive to changes in fg. At I/sub C/=5 A, the value of |V/sub g//sup -/| for stable modulation shows a maximum between 8 kHz and 10 kHz. The Cs pressure, I/sub C/, fg, and V/sub g//sup +/ all affect the ignition delay time; depending on the operating conditions, it increases from 5-30 /spl mu/s to an equilibrium value of 10-45 /spl mu/s during the first 2 ms in the pulse train.<
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