Power plants – Reaction motor – Electric – nuclear – or radiated energy fluid heating means
Patent
1995-02-15
1996-04-23
Casaregola, Louis J.
Power plants
Reaction motor
Electric, nuclear, or radiated energy fluid heating means
31511141, F03H 100
Patent
active
055092667
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a device for measuring variations in the thrust of a plasma accelerator with closed electron drift comprising a main annular channel for ionization and acceleration, at least one hollow cathode disposed outside the main channel and downstream therefrom, an anode, ionizable gas feed means associated respectively with the hollow cathode and with the anode, and magnetic field creation means.
PRIOR ART
Electrical accelerators are intended essentially for space propulsion applications. As sources of ions or of plasma they are used in terrestrial applications, in particular for ion machining. Because of their high specific impulse (1500 s to 6000 s) they make considerable mass savings possible on satellites compared with accelerators that provide thrust chemically.
Ion thrusters can be divided into several categories. Most ion thrusters have in common the fact that their ionization function is clearly separated from their ion acceleration function.
Plasma accelerators of the "closed electron drift" type, also known as "stationary plasma accelerators", or in the United States of America as "Hall current accelerators" differ from the other categories by the fact that ionization and acceleration are not kept separate and that the acceleration zone includes equal numbers of ions and of electrons, thereby making it possible to eliminate any space charge phenomenon.
Conventional ion thrusters produce thrust F which can be derived analytically from the acceleration voltage V and the ion beam current I using the following equation:
Stationary plasma accelerators present an ion energy distribution that also depends on operating conditions, so it is therefore not possible to use an identical analytic equation to determine their thrust.
Stationary plasma accelerators are described in an article by L. H. ARTSIMOVITCH, et. al, published in 1974.
An improved plasma accelerator of the closed electron drift type is described in French patent application 92 08744, filed Jul. 15, 1992 and described briefly with reference to FIG. 1.
FIG. 1 shows an example of a plasma accelerator 20 with closed electron drift which comprises a set of parts 22 made of insulating material defining an annular channel 21 formed upstream from a first part constituted by a buffer chamber 23 and downstream from a second part constituted by an acceleration channel 24.
The radial size of the annular chamber 23 is preferably about twice the radial size of the acceleration annular channel.
An anode 25 is connected by an electrical line 43 to a DC source 44 (which for example, may be at about 200 V to 400 V) and is disposed on the insulating parts 22 defining the annular channel 21, in a zone situated immediately downstream from the buffer chamber 23, at the inlet to the acceleration channel 24. The line 43 for powering the anode 25 is disposed in an insulating tube 45 that passes through the end of the accelerator as constituted by a plate 36 forming a magnetic yoke and through parts 223 and 224 made of insulating material that define the buffer chamber 23.
A tube 26 for feeding ionizable gas, such as xenon, also passes through both the yoke 36 and the end wall 223 of the buffer chamber 23 to open out into an annular gas manifold 27 placed in the end wall of the buffer chamber 23.
The channel 21 defined by the set of insulating parts 22 is placed in a magnetic circuit essentially made up of three coils 31, 32, and 33 and of pole pieces 34 and 35.
External and internal plane pole pieces 34 and 35 are placed in the outlet plane of the accelerator outside the acceleration channel 24, and they define magnetic field lines which are substantially parallel to the outlet plane 59 of the accelerator 20 in the open downstream portion of the acceleration channel 24.
The magnetic circuit constituted by the pole pieces 34 and 35 is closed by an axial central core 38 and by connection bars 37 disposed at the periphery of the accelerator in an essentially cylindrical configuration, with the central core 38 that is
REFERENCES:
patent: 4821508 (1989-04-01), Burton et al.
patent: 5051659 (1991-09-01), Uhm et al.
patent: 5241244 (1993-08-01), Cirri
"Experimental Study of the Azimuthal Electron Drift Current in Hall Accelerators," Barkalov, et al, vol. 35, No. 2, Feb. 1990, New York, pp. 238-239, Soviet Phys. Tech. Phys.
"Determination of the Radial Center of Gravity of an Azimuthal Drift Current In Accelerators with Closed Electron Drift", A. I. Bugrova, et al, vol. 25, No. 10, Oct. 1980, New York, Soviet Phys. Tech. Phys., pp. 1307-1309.
"Non-Contaminating Electron Density Monitor for RF Induction Plasmas", vol. 34, No. 11, Apr. 1992, New York, pp. 424-XP303314, IBM Technical Disclosure Bulletin.
"Induction Method for Measuring the Azimuthal Drift Current in a Hall-Current Accelerator", V. N. Dem'yanenko, et al, vol. 23, No. 3, Mar. 1978, New York, pp. 376-377, Soviet Phys. Tech. Phys.
"Initial Operating of A 10 ms, Quasi-Steady, Multi--Megawatt, Coaxial Plasma Thruster", J. T. Scheuer, et al, vol. 271/3, Albuquerque, N.M., pp. 1327-1334, Proceedings of th 10th Symposium of Space Nuclear Power and Propulsion, Jan. 10-14, 1993.
Bougrova Antonina
Kharchevnikov Vadim
Morozov Alexei
Valentian Dominique
Casaregola Louis J.
Societe Europeenne de Propulsion
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