INVESTIGATIONS ON THE DIRECT CONVERSION OF NUCLEAR FISSION ENERGY TO ELECTRICAL ENERGY IN A PLASMA DIODE. VOLUME II.
Abstract
Inpile experiments on the transport of thermionic electrons through the argon-cesium plasma are described and the results are compared with predictions of a diffusion-loss dominated transport model and recombination-dominated limits. The inpile experiments were performed using ceramic-metal diodes of parallel-plane configuration, with an unclad thermionic-electron and fission-fragment emitter, and also containing an evacuated electron-gun section by means of which the emitter temperature could be heated in a manner independent of the nuclear heat. Maxium short-circuit current densities of about 0.3 A/sq cm were obtained in these diagnostic diodes at a neutron flux value of around ten trillion per sq cm per sec. These current densities were much higher (by factors of 5 to 30) than those predicted by the diffusion-loss dominated transport-model. Furthermore, in marked contrast with theory, these current densities were similar for two values of emitter-collector spacing (0.15 and 0.3 cm). This makes the present system appear more attractive for practical thermionic applications than can be expected on the basis of simple transport-models. Quantitative recombination-dominated limits suggest that the experimental findings are more consistent with a uniform emitter-collector electron density profile. As a result, it is tentatively suggested that the incidence of excited and charged argon species upon cesium-covered metal surfaces gives rise to a wall source of both ions and electrons which in effect significantly reduces the expected ambipolar diffusion loss of charge from the plasma.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 28, 1968
- Accession Number
- AD0391707
Entities
People
- Charles B. Leffert
- David B. Rees
- Fay E. Gifford