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High frequency waves in ionized gases
224
ABSTRACTS
composed of ions and electrons. An unsteady model is set up, wherein the ion and electron density profiles, which are obtained as a function of space and time, correspond to the profiles at a given cross-section aft of the body in the actual problem. The Boltzmann equation with electric effects taken into account is utilized and solutions are obtained numerically. Perturbations on the velocity distribution functions are calculated
HIGH
FREQUENCY
over small increments of time which then yield the magnitude of the electric effect over the next time increment. Calculations indicate that the charge density gradients extend several body radii downstream. These gradients are inherent to the rarefied flow over any vehicle and can significantly alter its detectability by electromagnetic signals.
WAVES IN IONIZED
GASES
S. C. BROWN Massachusetts Institute of Technology
A review will be given of the propagation of electromagnetic waves through an anisotropic ionized gas in order to elucidate the following studies presently under way in our laboratory: (a) The emission of incoherent microwave radiation from plasmas (both with or
without external magnetic fields) various degrees of transparency. (b) The contribution of ions frequency of the plasma, attention directed toward tion of various types of ion
of
to the radiowith specific an investigaresonances.
EXPERIMENTAL INVESTIGATION OF PLASMA SHEATH PROPERTIES OF A RE-ENTRY VEHICLE W. ROTMAN and G. MELTZ Air Force Cambridge Research Laboratories
The effects of the plasma sheath, which surrounds a re-entry vehicle, upon the transmission and reception of radio signals will be investigated by means of an instrumented nonablative nose cone to be flown in a re-entry trajectory from Cape Canaveral in the latter part of 1960. The flight profile is such that an altitude of 100 miles and a maximum velocity of 18,000 ft/sec will be reached in a shallow (10-20 degrees) re-entry path. The instrumentation consists of five microwave transmitters, in the L, S, C and X-band frequency ranges, and S and C band receivers. The S and C band units also serve as the radar beacons while telemetry data is transmitted on the X-band frequencies. Farameters to
be measured include signal attentuation and coherence, pulse deterioration, and plasma noise generation as a function of altitude and velocity. These results will be compared with estimated values from modified isentropic calculations and, also with results from the University of California’s hypersonic wind tunnel tests. Subsequent to the flight test detailed nonequilibrium real gas calculations will be programmed to provide an exact theoretical comparison. The radiation patterns of the antennas on the nose cone will be changed in shape by the plasma sheath. This effect is being simulated experimentally by the use of a lossy artificial dielectric which has the same propagation characteristics
ABSTRACTS
composed of ions and electrons. An unsteady model is set up, wherein the ion and electron density profiles, which are obtained as a function of space and time, correspond to the profiles at a given cross-section aft of the body in the actual problem. The Boltzmann equation with electric effects taken into account is utilized and solutions are obtained numerically. Perturbations on the velocity distribution functions are calculated
HIGH
FREQUENCY
over small increments of time which then yield the magnitude of the electric effect over the next time increment. Calculations indicate that the charge density gradients extend several body radii downstream. These gradients are inherent to the rarefied flow over any vehicle and can significantly alter its detectability by electromagnetic signals.
WAVES IN IONIZED
GASES
S. C. BROWN Massachusetts Institute of Technology
A review will be given of the propagation of electromagnetic waves through an anisotropic ionized gas in order to elucidate the following studies presently under way in our laboratory: (a) The emission of incoherent microwave radiation from plasmas (both with or
without external magnetic fields) various degrees of transparency. (b) The contribution of ions frequency of the plasma, attention directed toward tion of various types of ion
of
to the radiowith specific an investigaresonances.
EXPERIMENTAL INVESTIGATION OF PLASMA SHEATH PROPERTIES OF A RE-ENTRY VEHICLE W. ROTMAN and G. MELTZ Air Force Cambridge Research Laboratories
The effects of the plasma sheath, which surrounds a re-entry vehicle, upon the transmission and reception of radio signals will be investigated by means of an instrumented nonablative nose cone to be flown in a re-entry trajectory from Cape Canaveral in the latter part of 1960. The flight profile is such that an altitude of 100 miles and a maximum velocity of 18,000 ft/sec will be reached in a shallow (10-20 degrees) re-entry path. The instrumentation consists of five microwave transmitters, in the L, S, C and X-band frequency ranges, and S and C band receivers. The S and C band units also serve as the radar beacons while telemetry data is transmitted on the X-band frequencies. Farameters to
be measured include signal attentuation and coherence, pulse deterioration, and plasma noise generation as a function of altitude and velocity. These results will be compared with estimated values from modified isentropic calculations and, also with results from the University of California’s hypersonic wind tunnel tests. Subsequent to the flight test detailed nonequilibrium real gas calculations will be programmed to provide an exact theoretical comparison. The radiation patterns of the antennas on the nose cone will be changed in shape by the plasma sheath. This effect is being simulated experimentally by the use of a lossy artificial dielectric which has the same propagation characteristics