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Title: ACCELERATION OF PLASMAS BY INDUCTIVELY GENERATED ELECTROMAGNETIC FIELDS

Abstract

Some aspects of the induction accelerator that can be derived theoretically are brought out. Isolated particle behavior within a cylindrical coil is studied. Charges gain energy from the azimuthally directed electric field; their paths are turned in the radial and axial directions by the magnetic field, and they eventually are ejected out the end of the coil. The exact paths of electrons and helium and argon ions under various field conditions are calculated by analog computer techniques, and from these calculations are obtained the velocity and angle that the ejected particles ultimately obtain. The quantitative dependence of ejection characteristics on initial position of the particle is found. The difference in behavior when the field period is much less than and much more than the time taken for the particle to be ejected from the accelerator is also noted. Induction acceleration of plasmas is theoretically considered, at first under the simplifying assumption that the coil is very long. This assumption eliminates radial magnetic field components and thrust in the axial direction, but it realistically treats the radial motion, which is an important energy-transferring process in the experimental device. The effect of self-fields (electric, from charge separation, and magnetic, from the gasmore » current) on the radial motion is studied; even at quite low densities the particles are found to be bound to one another by these fields. The radial motion of such low-density plasmas is calculated. The radial dependences of magnetic field and current density within the ionized gas are shown to be approximated by Bessel functions. At high densities a skin current is shown to form, and to prevent penetration of the magnetic field into the interior of the plasma. For these high densities a snowplow'' analysis is used to calculate the radial motion of the plasma. The axial motion of plasma within a finite sized coil is considered. Qualitatively, it is argued that the majority of energy in axial motion arises from energy transmitted to the plasma by radial compression, and then converted to axial motion in the diverging magnetic nozzle. Characteristics of the flowing gas that can be obtained from observation of the advancing shock wave are brought out. Experiments using an induction accelerator are described. The accelerator is a 10 cm long by 10 cm in diameter, single-turn cylindrical coil driven by a 57.5 mu fd capacitor bank. Capacitor voltages in the 5 to 10 kilovolt range are used. Ionization of the gas within the coi1 is accomplished partly by a high frequency preionization circuit and partly by the accelerator field itseif. Data on helium and argon over the pressure range of 0.010 to 1.00 mm Hg are reported. Specifically, kinetic characteristics (radial and axial motion, momentum and energy) and internal structure (current and charge) of the accelerating ionized gas are studied. The measurements are correlated whenever possible with each other and with the theory. Axial velocity of the gas as it emerges from the coil is typically 0.5 to 10 cm per microsecond. Approximately 10 to 50 joules is transferred from the circuit to the gas; this represents up to 10 percent of the energy available in the magnetic field of the coil, and about half this transferred energy goes into directed motion of the gas. Ion temperatures, calculated from observations of the radial compression and axial shock, are in the 25,000 to 100,000 deg K range; electron temperature, measured for one pressure by an electric probe, is about one-third the concurrent ion temperature. Characteristics of a propulsion motor using the induction principle are estimated. (Dissertation Abstr., 22: No. 7, 1962.)« less

Authors:
Publication Date:
Research Org.:
Originating Research Org. not identified
OSTI Identifier:
4790894
NSA Number:
NSA-17-000989
Resource Type:
Thesis/Dissertation
Resource Relation:
Other Information: Thesis. Orig. Receipt Date: 31-DEC-63
Country of Publication:
Country unknown/Code not available
Language:
English
Subject:
PHYSICS; ABSORPTION; ACCELERATORS; ANALOG SYSTEMS; ANGULAR DISTRIBUTION; ARGON; BESSEL FUNCTIONS; CAPACITORS; CHARGED PARTICLES; CIRCUITS; COILS; CONFIGURATION; CURRENTS; CYLINDERS; DENSITY; DIFFERENTIAL EQUATIONS; ELECTRIC CHARGES; ELECTRIC FIELDS; ELECTRIC POTENTIAL; ELECTROMAGNETIC FIELDS; ELECTRONS; EMISSION; ENERGY; FREQUENCY; GAS FLOW; GASES; HELIUM; INDUCTION; INTERACTIONS; IONIZATION; IONS; MAGNETIC FIELDS; MAGNETS; MATHEMATICS; MEASURED VALUES; MECHANICS; MOMENTUM; MOTION; NOZZLES; NUMERICALS; PLANNING; PLASMA; PRESSURE; PROPULSION; SEPARATION PROCESSES; SHOCK WAVES; SURFACES; TEMPERATURE; TESTING; TRANSPORT; VELOCITY

Citation Formats

Miller, D B. ACCELERATION OF PLASMAS BY INDUCTIVELY GENERATED ELECTROMAGNETIC FIELDS. Country unknown/Code not available: N. p., 1961. Web.
Miller, D B. ACCELERATION OF PLASMAS BY INDUCTIVELY GENERATED ELECTROMAGNETIC FIELDS. Country unknown/Code not available.
Miller, D B. Sun . "ACCELERATION OF PLASMAS BY INDUCTIVELY GENERATED ELECTROMAGNETIC FIELDS". Country unknown/Code not available.
@article{osti_4790894,
title = {ACCELERATION OF PLASMAS BY INDUCTIVELY GENERATED ELECTROMAGNETIC FIELDS},
author = {Miller, D B},
abstractNote = {Some aspects of the induction accelerator that can be derived theoretically are brought out. Isolated particle behavior within a cylindrical coil is studied. Charges gain energy from the azimuthally directed electric field; their paths are turned in the radial and axial directions by the magnetic field, and they eventually are ejected out the end of the coil. The exact paths of electrons and helium and argon ions under various field conditions are calculated by analog computer techniques, and from these calculations are obtained the velocity and angle that the ejected particles ultimately obtain. The quantitative dependence of ejection characteristics on initial position of the particle is found. The difference in behavior when the field period is much less than and much more than the time taken for the particle to be ejected from the accelerator is also noted. Induction acceleration of plasmas is theoretically considered, at first under the simplifying assumption that the coil is very long. This assumption eliminates radial magnetic field components and thrust in the axial direction, but it realistically treats the radial motion, which is an important energy-transferring process in the experimental device. The effect of self-fields (electric, from charge separation, and magnetic, from the gas current) on the radial motion is studied; even at quite low densities the particles are found to be bound to one another by these fields. The radial motion of such low-density plasmas is calculated. The radial dependences of magnetic field and current density within the ionized gas are shown to be approximated by Bessel functions. At high densities a skin current is shown to form, and to prevent penetration of the magnetic field into the interior of the plasma. For these high densities a snowplow'' analysis is used to calculate the radial motion of the plasma. The axial motion of plasma within a finite sized coil is considered. Qualitatively, it is argued that the majority of energy in axial motion arises from energy transmitted to the plasma by radial compression, and then converted to axial motion in the diverging magnetic nozzle. Characteristics of the flowing gas that can be obtained from observation of the advancing shock wave are brought out. Experiments using an induction accelerator are described. The accelerator is a 10 cm long by 10 cm in diameter, single-turn cylindrical coil driven by a 57.5 mu fd capacitor bank. Capacitor voltages in the 5 to 10 kilovolt range are used. Ionization of the gas within the coi1 is accomplished partly by a high frequency preionization circuit and partly by the accelerator field itseif. Data on helium and argon over the pressure range of 0.010 to 1.00 mm Hg are reported. Specifically, kinetic characteristics (radial and axial motion, momentum and energy) and internal structure (current and charge) of the accelerating ionized gas are studied. The measurements are correlated whenever possible with each other and with the theory. Axial velocity of the gas as it emerges from the coil is typically 0.5 to 10 cm per microsecond. Approximately 10 to 50 joules is transferred from the circuit to the gas; this represents up to 10 percent of the energy available in the magnetic field of the coil, and about half this transferred energy goes into directed motion of the gas. Ion temperatures, calculated from observations of the radial compression and axial shock, are in the 25,000 to 100,000 deg K range; electron temperature, measured for one pressure by an electric probe, is about one-third the concurrent ion temperature. Characteristics of a propulsion motor using the induction principle are estimated. (Dissertation Abstr., 22: No. 7, 1962.)},
doi = {},
journal = {},
number = ,
volume = ,
place = {Country unknown/Code not available},
year = {1961},
month = {1}
}

Thesis/Dissertation:
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