RESEARCH ON UNSTABLE OSCILLATIONS IN ENERGETIC ARCS.
Abstract
Gas-fed hollow-cathode vacuum arcs in argon, nitrogen, hydrogen and helium were studied. These arcs operate in a magnetic field of several kG and have current density approx. 100 A/sq.cm. voltage approx. 100 V, density approx. 2 x 10 to the 14th power/cc, electron temperature approx. 1 eV, and ion temperature ranging from 2 eV in hydrogen to 32 eV in argon. Temperatures were determined spectroscopically. The arc column is essentially completely ionized and consists largely of doubly charged ions (except in hydrogen). The current is carried by a small fraction (approx. 0.02) of the electrons having temperature 20-50 eV--much higher than the main electron population. These fast electrons control the conductivity at a sufficiently high value to make the longitudinal electric field very small. They acquire energy in passing through the cathode sheath and lose it in coulomb collisions with slow electrons, in ionizing and exciting ions, and in exciting drift waves. In spite of these losses they reach the anode with energies of 20-50 eV. More than half of the input power to the argon arc is radiated in the vacuum ultraviolet. Azimuthally propagating drift waves are present at approx. 35 kc and in the range 150 kc to several Mc. The latter are excited by the fast electrons and heat the ions by cyclotron absorption. Dispersion relations for these waves are presented. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 27, 1966
- Accession Number
- AD0634023
Entities
People
- Carl B. Kretschmer
Organizations
- Aerojet Rocketdyne Holdings