Probe for Measuring Ion Density in Slightly Ionized, High Speed Flow
- 1 June 1966
- journal article
- research article
- Published by AIP Publishing in Review of Scientific Instruments
- Vol. 37 (6), 775-785
- https://doi.org/10.1063/1.1720321
Abstract
A probe made of a hollow glass cylinder is placed with its axis parallel to a slightly ionized, high speed flow. Biased electrodes on the inside surface collect the ions and the electrons entering the probe. The charged particle density is obtained by dividing the collection current by the product of the probe entrance area, the gas velocity, and the charge per particle. In order to establish that all charged particles entering the probe are collected, it is verified that no particles are attracted by a pair of auxiliary electrodes downstream of the main ones. Proper functioning also requires negligible charged particle production inside the probe, and furthermore that the velocity of the charged particles at the probe entrance be equal to the flow velocity. The probe was used to obtain ion density profiles behind shock waves of Mach numbers 6 to 9 in air at initial pressures of 50 to 400 μ Hg. Ion densities measured were in the range 107 to 1010 cm−3. Above this range, total collection was prevented by space charge effects. The equilibrium ion densities measured are in satisfactory agreement with theory. The values obtained for the ionization relaxation time are probably influenced by the presence of impurities.Keywords
This publication has 15 references indexed in Scilit:
- Nonequilibrium anomalies in the development of diffusion flames.AIAA Journal, 1966
- Theory of electrostatic double probe comprised of two parallel plates.AIAA Journal, 1966
- Compressible plasma flow over a biased bodyAIAA Journal, 1965
- Weakly ionized nonequilibrium viscous shock- layer and electrostatic probe characteristicsAIAA Journal, 1965
- A general theory for the flow of weakly ionized gasesAIAA Journal, 1964
- Rate of Ionization Behind Shock Waves in Air. II. Theoretical InterpretationsPhysics of Fluids, 1963
- Testing Time and Contact-Zone Phenomena in Shock-Tube FlowsPhysics of Fluids, 1961
- On Flow Duration in Low-Pressure Shock TubesPhysics of Fluids, 1960
- Theory of the Stagnation-Point Langmuir ProbePhysics of Fluids, 1960
- An approximate measurement of the ionization time behind shock waves in airJournal of Fluid Mechanics, 1958