Cs-Ba Tacitron: I. Extinguishing Characteristics
Abstract
The extinguishing characteristics of a Cs-Ba tacitron as a switch/inverter are investigated experimentally in three modes of operation: breakdown mode, I-V mode, and current modulation mode. Operation parameters measured include switching frequency up to 8 kHz, hold off voltage up to 180 V, current densities in excess of 15 A/cm2, switch power density of 1 kW/cm2, voltage drop as low as 1.5 volts, for a switching efficiency in excess of 94% at collector voltages greater than 30 V. The voltage drop during both the I-V and current modulation modes strongly depend on the Cs pressure and to a lesser extent on the emission properties of the emitter (i.e. emitter temperature and Ba pressure). Increasing the Cs pressure and/or the emission current decreases the voltage drop in the triode sections. However, for the same initial Cs pressure and emission conditions, the voltage drop in the I-V mode is usually lower than that during current modulation. Results show that at an initial Cs pressure of 20 mtorr, Ba pressure of 0.1 mtorr, and emitter temperature of 1400 C, the voltage drop in the triode section in the I-V mode could be as low as 1.5 V. At the same operation condition during stable current modulation, so long as the discharge current is kept lower that the emission current, the voltage drop could be as low as 3 V. The Cs pressure, Ba pressure and emitter temperature influence not only the voltage drop but also the stable current modulation of the device (i.e. ignition and extinguishing of the discharge occur when positive and negative pulses are applied to the grid, respectively). Results show that in order for stable modulation to occur the initial amount of Cs atoms in the discharge volume at the time of ignition should be sufficiently high, however, in order to successfully extinguish the device, the heavy components in the discharge volume should be sufficien
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1992
- Accession Number
- ADA338912
Entities
People
- Chris Murray
- Mohamed El-genk
Organizations
- University of New Mexico