On the Distribution of Ions in the Plasma of an Arc Discharge,
Abstract
Certain features of the axial distribution of ions and neutral atoms in the interelectrode space of a half-wave low-current a-c arc have been studied. The degree of ionization of the iron atoms in the positive column depends upon whether these atoms enter the plasma from the cathode or the anode: when the iron vaporizes from the anode, the degree of ionization is higher than when it vaporizes from the cathode. In order to explain this phenomenon, it is necessary to assume that the ion concentration is determined not only by the conditions of thermal ionization, but also depends upon the entry of ions from the near-electrode regions under the action of the field and diffusion. The true value of the degree of ionization differs from the equilibrium value given by Saha's formula. The magnitude of the deviation depends on the field intensity in the column, the concentration of nautral atoms, and also on the ion-concentration gradients; its sign is determined by the polarity of the electrode from the surface of which the given element vaporizes. This effect is not just observed in the case of an arc between silver and aluminum electrodes, for when the polarity of these electrodes changes, the effective ionization potential of the plasma changes, and this compensates for the effect of the field. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 07, 1962
- Accession Number
- AD0292209
Entities
Organizations
- National Air and Space Intelligence Center