US3304717A - Electrical propulsion unit for use in rarefied atmospheres - Google Patents

Description

Feb. 21, 1967 H. GUTTON ETAL ELECTRICAL PROPULSION UNIT FOR USE IN RAREFIED ATMOSPHERES 2 Sheets-Sheet 1 Filed June 24, 1964 24 /rcuit-breaker Central Peat/Pier Pans/armer P- oscl /atar Source of cums/16L T Feb. 21, 1967 H. GUTTON ETAL 3,304,717

ELECTRICAL PROPULSION UNIT FOR USE IN RAREFIED ATMOSPHERES Filed June 24, 1964 2 Sheets-Sheet 2 United States Patent Office 3,304,717 Patented Feb. 21, 1967 3,304,717 ELECTRICAL PROPULSION UNIT FOR USE IN RAREFIED ATMOSPHERES Henri Guttou, Neuilly-sur-Seine, and Maurice Pierre Joseph Fournet, Vincennes, France, assignors to Sud- Aviation Societe Nationale de Constructions Aeronautiques. Paris, France Filed June 24, 1964, Ser. No. 377.745 Claims prioritv, application France, July 2, 1963, 940,046, Patent 1,369,470 9 Claims. (Cl. 60-202) This invention relates to a device for imparting orientated (hereinafter referred to as vectored) impulses to an object moving through a rarefied atmosphere, and is more particularly though not exclusively applicable for correcting the velocity or attitude of a space vehicle such as an artificial satellite.

By reason of the very small gravitational force acting on such moving objects, a very small force will suflice to move a relatively large mass under such conditions.

Chemical rockets have been used to this end but entail the need to carry a large quantity of fuel, thus making them unduly heavy.

Recourse has also been had to electric propulsion units in which the thrust is obtained by ejecting a small mass of elementary particles possessed of very high velocity.

Among the latter-mentioned types of propulsion units may be mentioned arc or resistance type electrothermal engines, ion engines, magnetohydrodynamic engines, and plasma engines with heated wire electrodes. All these propulsion units must be equipped either with means for generating the heat required for particle emission, or with a dual electric power supply system, and in either case it is mandatory to provide a source capable of supplying the power required, and such a source is liable to be too heavy.

All the foregoing systems referred to have the disadvantage of their large weight or their complexity, or else of the short life of their particle emitter as the result of heat losses due to vaporization, thus necessitating replacement of the emitter for space flights of long duration. Moreover, in certain cases, the positive or negative charge of the particles emitted and their attraction by the vehicle itself immediately subsequent to ejection implies the use of a particle neutralization system.

It is the object of the present invention to provide a simple, lightweight electric propulsion unit operating under cold conditions, from which all the particles emitted are neutral, which has satisfactory energy efficiency and which can therefore be used with advantage on space vehicles.

The invention is based on the following successive observations made by the applicants:

If one takes a straight conductive element initially assumed to be exposed to the surrounding air and if one causes direct current of increasing intensity to flow through this conductor, then the temperature of the latter will gradually rise until the current is cut off by a local melting process.

If instead of flowing direct current through the con ductor the latter is subjected to current pulses of short duration with steep leading edges, for instance by causing the current discharged by a capacitor to flow through the conductor, while at the same time gradually increasing the amplitude of the current, then the temperature of the conductor at the end of the pulse gradually increases until a break takes place through melting.

Repeating the same experiments in a rarefied atmosphere with an ambient pressure below 133.10 pascals, 10* Torr, or 136.10* leg/c11 say if the conductor is caused to be the seat of direct current or low-frequency current, it will begin to redden and will then initiate an evaporation process which is progressively accelerated until the circuit is broken.

When the conductor is subjected to brief pulses with steep leading edges under such rarefied environmental conditions, the phenomenon is completely transformed. The conductor apparently remains cold and, above a certain threshold, a brief flash occurs around the conductor. Sensors positioned remote from the conductor indicate the flight of neutral or electrified particles through the surrounding space at very high velocities of the order of several tens of kilometres per second. Indeed, everything suggests that the flow of the current with the steep leading edge no longer takes place through the entire body of the conductor but is confined toan extremely thin surface layer thereof which is destroyed by the current, after which the latter no longer flows through the conductor itself but through the plasma surrounding it.

Most of the electrical energy supplied to the conductor, instead of appearing in the form of heat within the conductor itself, is converted into kinetic energy imparted to elementary particles.

It is noteworthy that the total mass ejected at each impulse is extremely low, that this ejected mass appears only in the form of elementary particles and, lastly, that the velocities imparted to the particles are very considerable. It was also observed that a given conductor could withstand a considerable number of impulses.

With a view to utilizing this property in devices designed to impart to a moving object, in a rarefied atmospherc, vectored impulses for modifying its velocity and/or its attitude, the present invention provides an electric propulsion unit characterized in that it comprises a conductor inserted into a circuit which supp-lies current pulses of short duration but steep leading edge, which conductor is associated to means for vectoring the elementary particles possessed of very high velocity which are generated by said conductor, the latter remaining apparently cold, and in the plasma surrounding it, the complete unit being disposed within an ambient atmosphere in which the prevailing pressure is below a few thousandths of a Torr or tenths of a gram per square centimetre. As a result, the elementary particles ejected in the direction predetermined by said vectoring means produce a likewise vectored propelling reaction force which is transmitted to the vehicle equipped with such a propulsion unit.

In one preferred form of embodiment, said vectoring means acts upon the conduct-or having a polydirectional emission environment in such manner that the joint action of the various ejected particles after reflection upon a mirror, for example, produce a vectored resultant impulse.

In an alternative form of embodiment, the vectoring system is a structural part of the conductor itself whereby the current is caused to flow preferentially over one of the conductor faces to the detriment of the others thereby furnishing an emission which is selectively directed.

This invention consequently contemplates industrial applications of such an electrical generator which may be, for example, correction of the velocity or attitude of a space vehicle such as an artificial satellite, or correction of the motion of a rotary engine by mounting such a generator at an extremity of a lever arm, said generator being used as a single unit forming one element of a group of generators.

The description which follows with reference to the accompanying non-limitative exemplary drawings will give a clear understanding of how the invention can be carried into practice and will disclose yet further features thereof.

In the drawings:

FIG. 1 is a block diagram of an electric power supply for a propulsion unit according to the invention;

FIG. 2 schematically illustrates a first constructional form of a propulsion unit according to the invention;

FIGS. 3 and 4 are respectively a plan view with partial cut-away and a sectional view through the line IV-IV of FIG. 3 of a possible form of embodiment of a propulsion unit of the kind schematically illustrated in FIG. 2;

FIG. 5 is a schematic sectional view of the propulsive force generating element in an alternative form of embodiment of a propulsion unit according to the invention;

FIG. 6 is a perspective view with partial cut-away of a form of embodiment of the propulsion unit schematically illustrated in FIG. 5

FIG. 7 is a schematic sectional view of an alternative constructional form of the propulsive force generating element of FIG. 5;

FIG. 8 is a block diagram of another electric power supply for a propulsion unit according to the invention;

FIG. 9 is a sectional view similar to that of FIG. 4 for another form of embodiment of a propulsion unit of the kind schematically illustrated in FIG. 2;

FIG. 10 is a schematic sectional view of another alternative constructional form of the propulsive force generating element of FIG. 5;

FIG. 11 is a block diagram of the electric power supply for a group of propulsion units which act simultaneously; and

FIG. 12 is a block diagram of the electric power supply for a group of propulsion units which do not act simultaneously.

Referring first to FIG. 1, it will be seen that a source of low-voltage current 1 such as a solar battery is utilized to feed a self-oscillator 2 which transforms this direct current into alternating current. A transformer 3 steps up the voltage of this current which then passes through the rectifier 4. The system 1, 2, 3, 4 behaves in the manner of a high voltage D.C. source supplying current at several thousand volts. This source is used to charge a capacitor 5 of several microfarads through impedance coil 6. Reference numeral 7 designates a switch which may be either a mechanical switch, an electronic switch, an ion switch, or lastly either a natural electric arc or an electric are driven for instance by the pilot spark generating unit 24. The propulsive conductor to be energized is denoted by reference numeral 8. The capacitor may be charged directly by a source of high voltage direct current such as the source 1a of FIG. 8.

FIGS. 2 through 4 show a propulsion unit in which the conductor environment is operated upon whereby to cause the action of the various ejected particles to jointly produce a vectored or directed resultant impulse.

In this first form of embodiment of the propulsive con ductor, recourse is had to a linear conductor as desig nated in sectional form by the reference numeral 9 in FIG. 2, and this conductor is surrounded by a mirror 10, whereby only the particles ejected in the direction E give rise to a propulsive reaction force.

In this first constructional form of such a propulsion unit, shown in FIGS. 3 and 4, the propulsive conductor proper is a graphite rod 11. The current lead-in conductors 12 and 13 are two metal strips separated by an intermediate strip of insulating material 14 made, for instance, of laminated fiberglass. The two strips 12 and 13 are very closely spaced from each other in order to minimize the inductance of the circuit and facilitate the establishment of the current peak.

The mirror 15 is of cuplike shape, being made of glass or ceramic for instance, and being of substantially parallelopiped form with one face F missing.

Preferably, the conductive strips 12 and 13 are extended either by two bent parallel portions 12a and 13a as shown in FIG. 3, or by two parallel conductive strips respectively connected to the ends of the propulsive con- 4 ductor 11, whereby to director vector the ejection of the plasma which appears after ejection of the particles.

By reason of the small weight of its component parts, the propulsion unit of FIGS. 3 and 4 can be secured directly through the medium of the conductive strips 12 and 13, in view of the small thrusts generated by the unit and the low inertia loads set up during the acceleration period and due to the low weight of said propulsion unit. The latter may alternatively be used without the glass or ceramic cup 15, the insulating strip 14b then serving as a reflector as illustrated in FIG. 9 wherein the elements similar to those. of FIG. 4 have the same reference numerals followed by the letter b. Alternatively, also, the propulsion unit could be secured to the space vehicle through the insulating cup.

Reference is next had to FIGS. 5 through 7 for an illustration of a second type of propulsion unit according to the invention, in which the structure of the conductor itself is operated on in order to obtain preferential flow of the current over one of the conductor faces to the detriment of the others.

FIG. 5 schematically illustrates the propulsion force generating element of such a propulsion unit of the second type referred to. This element is a two-part element, of which one part 16 is made of a material such that a current with a steep leading edge remains concentrated on its outer surface with only very shallow penetration into its body, while the other part 17 is made of a material into which a current with a steep leading edge can penetrate more deeply.

A conductor of this type can be obtained, for instance,

by juxtaposing and bonding together two rods made of materials having different electrical conductivities, that of the part 17 being 50 to times lower than that of the part 16. As an example said rods are made of two sintered materials of different graphites, the more highly conductive rod being located at 16, i.e. on the same side as the emission E. The binding agent may be made conductive either by polymerization or by treating it with a conductive dopant. Alternatively, such a propulsion unit of the second type can be obtained by directly pressing two suitable powder preparations, i.e. having different conductivities within the aforementioned range, and these preparations are then solidified and rigidly united by polymerization, as in the fabrication of resistors utilized in the radio and electrical engineering art. In a resistor of this type, when an impulse occurs, the lines of current concentrate in the region of the surface e of the element 16 and the particles are ejected only through this face e and about a line at right angles thereto.

In the specific constructional form of a propulsion unit of the second type shown in FIG. 6, the two conductor elements 16a and 17a, the properties of which are similar to those of the elements 16 and 17 of FIG. 5, are embedded into supports 18 mounted on conductor strips 19 and 20 which are bent into Z-shape and themselves embedded into an insulating block 21 serving to secure the propulsion unit. These Z-shaped strips 19 and 20 are reversed between each other with their wings parallel. Their more distant wings which are connected to the conductor elements 16a and 17a can be extended in mutual parallelism, as at 1911 and 20a in FIG. 6, whereby to expel the plasma which appears after the particles have been ejected.

In order to cause the current lines to concentrate in the region of the face e of the propulsion element of FIG. 5, the three other faces of said element have disposed thereon a U-shaped channel section made of magnetic material. Alternatively, such concentration can be obtained in the manner shown in FIG. 7, the conductor 22 being then obtained by concretion into a U-shaped channel-section 23 in magnetic material, or by charging the zone 23a with magnetic powder over all sides of the conductor 22a other than its emitting face e. (FIG. 10).

It goes without saying that the current pulses may be repeated several times, whereby the cumulative successive impulses resulting therefrom produce a true propulsion effect. Indeed, such an experiment has been conducted by the applicants with complete success.

In its various applications, the subject electric propulsion unit of this invention may comprise, not one, but a plurality of propulsive elements of the type hereinbefore described, in order to increase the thrust otherwise than by merely increasing the size of each unit element or in order to obtain different effects at different times.

Thus, for increasing the thrust, a plurality of propulsive conductors 8a, 8b, by a common rectifier 4b, each one of said propulsive elements being associated with its capacitor 5a, 5b, its impedance coil 6a, 6b, and its switch 7a, 7b, controlled by the respective circu-it-breaker controlling unit 24a, 24b, as illustrated in FIG. 11.

In case it is desired to obtain different propulsive effects at different times,. the propulsion unit, as illustrated in FIG. 11, comprises a plurality of propulsion conductors 8c, 8d, 8e, which are energized by a common capacitor 50 through a selecting switch 25 remotely controlled by any known means.

Each one of conductors 8a, 8b, 8c, 8d, 8e the type illustrated in FIGS. 4 to 7, 9 and 10.

A propulsion unit according to this invention may be utilized in order to exert a direct thrust on an object moving through a rarefied atmosphere or through space. It may likewise be mounted on the end of a lever arm and act as a rotary engine usable for driving equipment in a vacuum.

The fact that the conductor apparently remains cold in operation indicates that the energy efficiency of the system is high. Indeed, the energy supply can be made virtually limitless by the use of solar batteries. In addition, in its specific application to space vehicles, the system permits flexible, inertia-free transmission of the commands received from the ground, from a programmed system, or from a pilot.

It will of course be understood that many modifications or substitutions of parts may be made to the specific embodiments as hereinbefore described without departing from the scope of the present invention as specified in the appended claims.

What We claim is:

1. An electric propulsion unit for use in rarefied atmospheres comprising, in combination, means for generating current pulses of short duration with a steep leading edge and, within an ambient atmosphere in which the prevailing pressure is below a few tenths of a gram per square centimetre, a conductor made of a graphite rod, two very closely spaced metal strips substantially parallel to said rod and respectively connected to the ends thereof, a strip of insulating material disposed between said metal strips, means for connecting said metal strips to said pulse generating means, whereby when said rod is fed by said pulse generating means it ejects elementary particles at very high velocities, while remaining cold and is surrounded by a plasma, and a mirror of reflecting material surrounding said rod and the parts of said metal strips connected thereto.

2. A propulsion unit according to claim 1, wherein said metal strips are etxended in mutual parallelism beyond the ends of said rod in a direction perpendicular to the latter toward the open end of the mirror.

3. A propulsion unit according to claim 1, wherein the mirror consists of a cup having a parallelopiped shape with an open face located on the same side of the metal strips as the graphite rod.

4. A propulsion unit according to claim 1, wherein the mirror consists of the strip of insulating material.

5. An electric propulsion unit for use in rarefied atmospheres comprising, in combination, means for generating is of are simultaneously energized current pulses of short duration with a steep leading edge and, within an ambient atmosphere in which the prevailing pressure is below a few tenths of a gram per square centimetre, a conductor consisting of a rectangular rod, means for connecting said conductor to said current pulse generating means, whereby when said conductor is energized by said pulse generating means it ejects elementary particles at very high velocities, while remaining cold and is surrounded by a plasma, and a U-shaped channel-section of magnetic material surrounding three faces of said rectangular rod the fourth face of which acts as an emission face for the elementary particles and the plasma.

6. An electric propulsion unit for use in rarefied atmospheres comprising, in combination, means for generating current pulses of short duration with a steep leading edge and, within an ambient atmosphere in which the prevailing pressure is below a few tenths of a gram per square centimetre, a conductor consisting of a rectangular rod, means for connecting said conductor to said current pulse generating means, whereby when said conductor is energized by said pulse generating means it ejects elementary particles at very high velocities, while remaining cold and is surrounded by a plasma, and a magnetic powder covering three faces of said rectangular rod the fourth face of which acts as an emission face for the elementary particles and the plasma.

7. An electric propulsion unit for use in rarefied atmospheres comprising, in combination, means for generating electric current pulses of short duration with a steep leading edge, a thick solid electrical conductor situated within an ambient atmosphere the pressure of which is less than a few tenths of a gram per square centimeter, means for electrically connecting said conductor to said electrical current pulse generating means, whereby when said conductor is energized by said generating means, under the action of each electrical current pulse having a steep leading edge, there is ejected from said conductor in substantially cold condition and without apparent deterioration, a small quantity of its constitutive material in the form of elementary particles, said elementary particles immediately generating a plasma under the influence of the electric voltage prevailing in said conductor, said plasma surrounding said conductor, and means for accelerating and directing said ejected particles and generated plasma.

8. An electric propulsion unit as claimed in claim 7, wherein said thick solid electrical conductor is constituted of two juxtaposed elementary conductors having different resistivities, said elementary conductors being juxtaposed whereby a preferential electric current flow is obtained in the elementary conductor having the lesser resistivity and consequent ejection of elementary particles is produced from the free surface of said conductors having the lesser resistivity in greater quantity relative to the ejection of particles produced at the contact face between said elementary conductors.

9. An electric propulsion unit for use in rarefied atmospheres comprising, in combination, means for generating electric current pulses of short duration with a steep leading edge, a thick solid electrical conductor situated within an ambient atmosphere the pressure of which is less than a few tenths of a gram per square centimeter, an electrical conductor constituted of two thick solid rods of electrically conductive materials the electrical conductivities of which differ from each other from about fifty fold to about a hundred fold, said rods being juxtaposed with interposition of a binding agent, the rod having the higher conductivity being disposed on the side of desired ejection of elementary particles under the action of said pulses, two electrically conducting strips electrically connected to said rods, with said rods disposed between said strips, said strip having parallel first wings on said side of desired ejection of said elementary particles and of a plasma they generate under the action of electric voltage in said rods, said 7 8 strips having second wings closer to each other on a sec- References Cited by the Examiner 0nd side opposite said side of desired ejection, insulating UNITED STATES PATENTS material between said second wings and electrical connecting means between said second wings and said generating 2,764,707 9/1956 Crawford et 313-63 means, whereby when said conductor is energized by said 5 2,940,011 6/1960 Kolb' generating means, ejection of elementary particles is pfo- 237x332 3/1961 duced on said side of desired ejection and, by ionization of 3204389 9/1965 Schwmghamer 60-355 X said particles, between said wings, there is formed a plasma which is propelled in the direction of the extremities of CARLTON CROYLE Pnmary Exammer' said first wings. 10 MARK M. NEWMAN, Examiner.

Claims (1)

1. AN ELECTRIC PROPULSION UNIT FOR USE IN RAREFIED ATMOSPHERES COMPRISING, IN COMBINATION, MEANS FOR GENERATING CURRENT PULSES OF SHORT DURATION WITH A STEEP LEADING EDGE AND, WITHIN AN AMBIENT ATMOSPHERE IN WHICH THE PREVAILING PRESSURE IS BELOW A FEW TENTHS OF A GRAM PER SQUARE CENTIMETRE, A CONDUCTOR MADE OF A GRAPHITE ROD, TWO VERY CLOSELY SPACED METAL STRIPS SUBSTANTIALLY PARALLEL TO SAID ROD AND RESPECTIVELY CONNECTED TO THE ENDS THEREOF, A STRIP OF INSULATING MATERIAL DISPOSED BETWEEN SAID METAL STRIPS, MEANS FOR CONNECTING SAID METAL STRIPS TO SAID PULSE GEN ERATING MEANS, WHEREBY WHEN SAID ROD IS FED BY SAID PULSE GENERATING MEANS IT EJECTS ELEMENTARY PARTICLES AT VERY HIGH VELOCITIES, WHILE REMAINING COLD AND IS SURROUNDED BY A PLASMA, AND A MIRROR OF REFLECTING MATERIAL SURROUNDING SAID ROD AND THE PARTS OF SAID METAL STRIPS CONNECTED THERETO.

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