MICROWAVE INVESTIGATION OF ELECTRICALLY DRIVEN SHOCK WAVES IN GASES
The application of microwave interaction with gaseous plasmas to the study of electrically driven shock waves in inert gases and gaseous plasmas is discussed. The microwave techniques used include: phase shift and resonart probe methods of measuring electron densities in the shock wave; Doppler frequency shift of a microwave signal reflected by the shock wave plasma which enables the velocity of propagation of shock waves to be measured. and radiometer measurements of the noise power radiated by the shock wave plasma in the microwave frequency range. The microwave measurements were supplemented by observations of the visible light emitied from the shocked gas and by voltage induced signals on small metallic probes placed in the path of the propagating shock waves. The investigated shock waves were in the Mach 4 to Mach 14 velocity range and were produced in neon and argon gases at pressures from 0.1 to 5 mm Hg. The shock waves were initiated by passing an intense electric discharge current through a portion of the gas filling the shock tube. It is demonstrated that the background gas through which the shock waves subsequently passed was ionized to a nonnegligible degree at the instart of the electrical discharge. It is shown that this preionization of the background gas is consistent with photoionization by photons of adequate energy from the discharge chamber of the shock tube. In particular it is shown that under the conditions of this experiment, the photoionization is consistent with ionizntion by x rays from the electron bombarded anode in the discharge chamber. The effect of the free electron constituent of the ionized background gas on the properties of shock waves as well as its direct effect on experimental observation techniques is discussed. In addition, the properties of the hot and highly ionized driver gas, which expands from the discharge chamber and closely follows the shock wave down the expansion chamber, is discussed. Particular emphasis is placed on the effect of the driver gas with regards to the establishment of an equilibrium state in the shocked gas. (Dissertation abstr., 24: No. 9, March 1964)
- Research Organization:
- Originating Research Org. not identified
- NSA Number:
- NSA-18-021448
- OSTI ID:
- 4001615
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
ARGON
BACKGROUND
CURRENTS
DENSITY
ELECTRIC DISCHARGES
ELECTRIC FIELDS
ELECTRIC POTENTIAL
ELECTRONS
EMISSION
EXPANSION
FREQUENCY
GASES
INERT GASES
INTERACTIONS
IONIZATION
LIGHT
MACH NUMBER
MEASURED VALUES
METALS
MICROWAVES
NEON
PHASE SHIFT
PHOTONS
PHYSICS
PLASMA
POWER
PRESSURE
PROBES
RADIOMETERS
REFLECTION
RESONANCE
SHOCK WAVES
SIGNALS
SPECTRAL SHIFT
SURFACES
THERMAL RADIATION
TUBES
VELOCITY
VESSELS
X RADIATION