SOURCES OF POSITIVE IONS FOR SPACE CHARGE NEUTRALIZATION AT LOW TEMPERATURES

Journal Article · Tue Jan 01 04:00:00 EST 1963 · Advanced Energy Conversion

DOI:https://doi.org/10.1016/0365-1789(63)90105-X· OSTI ID:4703827

Laubenstein, R A; Kaplan, C; Schneider, S; Creedon, J

Two methods for providing positive ions for space charge neutralization in thermionic cells using fossil fuels burned in air were investigated. These were: the thermionic emission of positive ions from solid compounds or mixtures of compounds, and the application of repeated short pulses of electric power to the converter to ionize the cesium vapor in the interelectrode space. Ion emission from the eucryptite analog of alkali metals and from mixtures containing alkali metal compounds was studied. Ion emission current densities of several milliamperes per cm/sup 2/ were obtained, but the lifetime of the emitter was often less than anticipated. Space charge neutralization electrons were demonstrated in a preliminary experiment using a three element structure with the ion emitter located between the electron emitter and collector. Pulsed operation of a thermionic diode was studied using a modified commercial diode to which cesium vapor was introduced at controlled pressures. During the application of a 10 to 20 v pulse, a discharge occurs in the cesium; and ions are formed. After the pulse is terminated, the ions formed neutralize the space charge and allow a high electron current to flow. The experimental tube has a nickel matrix emitter and a cesium coated copper collector so that the relative work functions of the emitter and collector do not allow useful power output densities to be obtained. However, an external bias voltage was used to adjust the interelectrode potential difference to simulate a thermionic converter. The diode current after the pulse was terminated was typically about 300 m amp compared to a steady state current before the pulse of about 0.8 m amp. Preliminary results indicate a charge transfer between emitter and collector between pulses that is 30 times the charge transfer during the pulse. Further work to optimize this ratio and to provide the pulse feedback of a portion of the diode output power is in progress. (auth)

• Research Organization: Marquardt Corp., Van Nuys, Calif.
• NSA Number: NSA-17-027984
• OSTI ID: 4703827
• Journal Information: Advanced Energy Conversion, Journal Name: Advanced Energy Conversion Vol. Vol: 3
• Country of Publication: Country unknown/Code not available
• Language: English

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ELECTRIC POTENTIAL
ELECTRICITY
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