Actual Current Density Research Articles

Efficiency of the Plasma Thermocouple

The efficiency of a thermionic converter containing cesium ions is calculated for the regime, in which the plasma density is sufficiently high so that the random current density, nev̄/4, is large compared to the actual current density. Under these circumstances, positive space charge barriers are set up at the electrodes, and the plasma region is many free paths in length. The output voltage V is determined for various currents by a consistent solution of the electrical and thermal conduction problems. The efficiency of the thermocouple is then deduced from the calculated current-voltage characteristic and the appropriate electron temperature distribution. Overall efficiencies up to 32% are predicted for a typical thermocouple circuit.

Results of Earth‐resistivity surveys near Watheroo, Western Australia, and at Ebro, Spain

In the study of terrestrial electricity and allied phenomena a knowledge of the specific resistance of the Earth's crust is essential. And while the resistivity of its constituent elements is generally well known for laboratory conditions, but few data are available on the resistivity of the crust itself and its distribution laterally and with depth. As a first step in acquiring these data, the Department of Terrestrial Magnetism of the Carnegie Institution of Washington has undertaken a series of resistivity surveys in regions where records of earth‐current potential gradient are being obtained. By combining the resistivity results with the records of potential gradient, the actual current densities may be compared.