Shock Production, Langmuir Probe Diagnostics, and Instabilities in a Nitrogen Plasma.
Abstract
In conjunction with the production of large amplitude Alfven waves in a nitrogen plasma, diagnostic measurements utilizing a single Langmuir probe were made with the plasma facility operating in the reflex arc configuration. The power supply used to produce an alternating magnetic flux in a coil wrapped about the longitudinal axis of the plasma column was inadequate to produce waves of sufficient amplitude for examination. Measurement of the characteristics of the nitrogen plasma was complicated by instabilities, which were identified as 360 cps modulation of the plasma and a rotational instability rotating in a right handed direction with respect to the longitudinal magnetic field. The rotational instability is composed of inner (Approx. 20kc) and outer (Approx. 200kc) lobes whose rotational frequencies are directly proportional to magnetic field strength. For intermediate parameters (B = 2400 gauss) the maximum electron temperature (4.2 plus or minus 0.2 eV) and density (5 x 10 to the -12th power/cc) were determined from the instability-modulated Langmuir probe characteristic. The minimum values were about a factor of two less, indicating a significant degree of instability. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1968
- Accession Number
- AD0847659
Entities
People
- Roger Charles Andrews
Organizations
- Naval Postgraduate School