Plasma antenna with two-fluid ionization current
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorTheodore R. Anderson
Life of this patent
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Abstract
A plasma antenna is provided having an ionizer, which when energized, generates a bounded or unbounded plasma column extending along a vertical axis. When ionization is initiated, the difference in the diffusion characteristics of ions and electrons and the resulting gas plasma produce a current pulse in a first direction. As the plasma extinguishes, the difference in relaxation times for the ions and electrons in the plasma produces a second current pulse of opposite direction. The alternating current pulses generate an electric field that radiates from the plasma column.
Claims14
An antenna comprising:
- ionization means for producing, when energized, a plasma in a volume extending upward along a vertical axis, said ionization means including means for generating in at least a portion thereof of the plasma an ionization of at least 1012 electrons per cubic centimeter during excitation and the plasma having a characteristic relaxation time when said ionization means is de-energized;
- and
- energizing means for repetitively energizing said ionization means such that the interval between successive energizations is less than the characteristic relaxation time.
A communications system for operating at a reference frequency comprising:
- a high-power laser that generates a laser beam along a laser axis;
- means for locating said laser with the laser axis in a vertical orientation directed into the atmosphere;
- energizing means for operating the laser in a pulsed manner thereby to produce a vertical plasma column in the atmosphere wherein the plasma has a characteristic relaxation time and the interval between successive pulses is less than the characteristic relaxation time;
- and
- modulation means responsive to a modulating signal for controlling the operation of said energizing means at a reference frequency that is less than the pulse repetition frequency of said energization means whereby alternately exciting and extinguishing the plasma produces an alternating current within the plasma at the reference frequency in response to the modulating signal.
A method for providing an antenna comprising:
- ionizing a volume extending upward to produce a plasma with ions and electrons characterized by different relaxation times upon termination of ionization;
- and
- controlling said ionizing to produce repeated ionizations in the column such that the interval between successive ionizations is less than the characteristic relaxation whereby the ions and electrons produce a current during the interval between repeated ionizations wherein said repetitive ionizing steps produce an ionization of at least 1012 electrons per cubic centimeter in at least a portion of the ion plasma.
Dependencies are inferred from the claim text.