Accession Number : ADA338615

Title :   Cs-Ba Tacitron: 2. Ignition Characteristics During Breakdown and Current Modulation Modes

Descriptive Note : Final rept. 1 Mar 91-12 Feb 92

Corporate Author : NEW MEXICO UNIV ALBUQUERQUE

Personal Author(s) : El-Genk, M. ; Wernsman, B. ; Murray, C.

PDF Url : ADA338615

Report Date : MAR 1992

Pagination or Media Count : 49

Abstract : Experiments are performed to determine the effects of the emitter temperature, Cs pressure, Ba pressure, and grid and collector voltages on the ignition of the Cs-Ba tacitron in the breakdown and current modulation modes. The values of off-time required for ignition in the breakdown mode are compared with those in the modulation mode for both stable and unstable current modulation conditions. Results show that in both modes of operation, the off-time required for ignition is strongly dependent on the Cs pressure in the gap and the applied positive grid potential but less dependent on the emitter temperature and the Ba pressure. Increasing the Cs pressure and/or the grid potential causes the off-time for ignition to decrease. It is determined that the net adsorption/desorption of Cs atoms onto the cold electrode surfaces during the off-time is negligible. Reducing the grid potential not only increases the off-time, hence decreasing modulation frequency of the device, but also can under certain conditions, cause current modulation to become unstable. Results show that the ignition duty cycle threshold for stable modulation is about 40-60%, regardless of the values of the applied positive grid potential. This threshold is weakly dependent on the Cs pressure, Ba pressure and the applied modulation frequency to the grid. However, increasing the grid potential for ignition beyond that corresponding to the duty cycle threshold causes the off-time required for ignition to decrease and the duty cycle of the device to increase.

Descriptors :   *CESIUM, *IGNITION, *ELECTRIC CURRENT, *MODULATION, *BARIUM, FREQUENCY, LOW TEMPERATURE, STABILITY, ADSORPTION, THRESHOLD EFFECTS, GRIDS, SURFACES, ELECTRODES, PRESSURE, EMITTERS, DESORPTION, BREAKDOWN(ELECTRONIC THRESHOLD).

Subject Categories : Inorganic Chemistry
      Electrical and Electronic Equipment

Distribution Statement : APPROVED FOR PUBLIC RELEASE