US3341720A - Apparatus for producing a beam of accelerated liquid metal droplets - Google Patents

Apparatus for producing a beam of accelerated liquid metal droplets Download PDF

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Publication number
US3341720A
US3341720A US446136A US44613665A US3341720A US 3341720 A US3341720 A US 3341720A US 446136 A US446136 A US 446136A US 44613665 A US44613665 A US 44613665A US 3341720 A US3341720 A US 3341720A
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droplets
liquid metal
electrodes
electrode
charge
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US446136A
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Edmund S Sowa
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Priority to US446136A priority Critical patent/US3341720A/en
Priority to GB12249/66A priority patent/GB1085485A/en
Priority to DE19661564965 priority patent/DE1564965B1/de
Priority to FR56316A priority patent/FR1474541A/fr
Priority to BE679106D priority patent/BE679106A/xx
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03H—PRODUCING A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03H1/00—Using plasma to produce a reactive propulsive thrust
    • F03H1/0087—Electro-dynamic thrusters, e.g. pulsed plasma thrusters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02K—JET-PROPULSION PLANTS
    • F02K5/00—Plants including an engine, other than a gas turbine, driving a compressor or a ducted fan
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03H—PRODUCING A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03H1/00—Using plasma to produce a reactive propulsive thrust
    • F03H1/0006—Details applicable to different types of plasma thrusters
    • F03H1/0025—Neutralisers, i.e. means for keeping electrical neutrality
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
    • H02N3/00—Generators in which thermal or kinetic energy is converted into electrical energy by ionisation of a fluid and removal of the charge therefrom
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T50/00—Aeronautics or air transport
    • Y02T50/60—Efficient propulsion technologies, e.g. for aircraft

Definitions

  • a source of alternating voltage having output terminals in phase opposition and symmetrical with respect to electrical ground.
  • a plurality of accelerating electrodes fixed in increasing spatial relationship are mounted along a line which includes the exit orifice of the nozzle.
  • the first of the electrodes is connected to one output terminal of the voltage source and is located adjacent the exit orifice of the nozzle to induce a charge in the liquid metal droplets as they are formed and accelerate the charged droplets away from the exit orifice of the nozzle toward the first electrode.
  • the remaining electrodes are successively connected to alternate terminals of the voltage source and the spacing between the electrodes is related to the frequency and amplitude of the voltage source and to the charge-to-mass ratio of the liquid metal droplets so as to cause the droplets to experience a unidirectional accelerating force.
  • This invention relates to apparatus and method for producing a beam of alternately charged groups of accelerated liquid metal droplets, and more particularly, to apparatus and method for producing alternately charged groups of accelerated liquid metal droplets using an oscillating electric field to induce a charge in the droplets as they form and accelerate them through the field as determined by the spacing and geometry of fixed electrodes.
  • the kinetic energy of the droplets may be used for various purposes.
  • One such purpose is to develop a very high DC potential by dividing the beam of alternately charged group of droplets into separate homogeneously charged beams and collecting the separated beams in electrically isolated containers. Separation is accomplished by passing the original beam through an electrostatic or magnetic field. The kinetic energy of the droplets is used to overcome the repulsive force exerted by the similarly charged containers. As the droplets are collected in the containers, charge of opposite polarity accumulates in the respective containers, and a substantial voltage differential builds up between the two containers.
  • Accelerating electrodes are mounted along a line with an increasing interval between electrodes as one proceeds from the first to the last.
  • Alternate electrodes are connected in common and an alternating voltage power source is used to energize the electrodes by connecting one polarity of the source to one commonly grouped set of electrodes and the other polarity of the power source to the second set of commonly grouped electrodes.
  • alternate polarity electric fields travel along the line determined by the electrodes. The field is similar to the electric fields produced in linear accelerators, see generally, Particle Accelerators, Livingston and Bleweet, McGraw-Hill (1962) chapter 10.
  • Liquid metal droplets of uniform diameter are formed at a nozzle adjacent to the first electrode.
  • the electrode As the electrode is energized by the power source, it induces a charge of opposite polarity in the droplets being formed. The droplets are then accelerated toward the inducing electrode and thence by the traveling electric field. As the first group of droplets passes the first electrode, the polarity of the source changes, reversing the field between electrodes. This group is then attracted to the second electrode while the first electrode acts both to repel this group and to induce a charge of opposite polarity in a second group of droplets forming at the nozzle. The second group of droplets is then accelerated toward the first reversing polarity.
  • This beam of alternately charged groups of accelerated liquid metal droplets may be used in a variety of ways. For example, in order to generate a very high DC potential, an electrostatic field is formed perpendicular to the line of travel of the beam to separate droplets of positive charge from droplets of negative charge. The positively charged droplets are then allowed to collect in one container and the negatively charged droplets to collect in a second container which is electrically isolated from the first container. A DC potential thus builds up between these two containers as charge accumulates, limited only by the kinetic energy of the accelerated droplets.
  • the present invention may also be put to use as a propulsion device or thrust producer. Obviously there is a force on the accelerating apparatus as a whole which is equal in magnitude and opposite in direction to the force exerted thereby on the droplets. This equal and opposite force may be used to accelerate the accelerating apparatus as a Whole relative to the droplets, similar to the ion and plasma engines described in Advanced Propulsion Concepts, supra. 7
  • electrodes 8, 9, 10 and 11 are constructed of metal tubing bent in a circle forming a to'rroid.
  • the electrodes 8, 9, 10 and 11 are held in place by electrode positioning brackets 12 and 13.
  • the metal brackets 12 and 13 are mounted on electrode supporting rods 14 and 15, respectively, which are also metal.
  • the brackets 12 and 13 are adjusted so that the centers of the torroidal electrodes 8, 9, 10 and 11 lie in a straight line which is perpendicular to the plate of the torroid.
  • the electrodes 8, 9, 10 and 11 are spaced at increasing intervals for reasons and in a manner explained below.
  • the straight line passing through the centers of the torroidal electrodes 8, 9, 10 and 11 includes an orifice 16 of a nozzle 18 at which liquid metal droplets are formed
  • the liquid metal which in the present device is the eutectic alloy of sodium and potassium'commonly known as NaK, is stored in container 30.
  • the NaK is fed into the nozzle 18 at an opening 28 through flexible tubing 32.
  • a transducer 33 for converting ultrasonic electrical power supplied at excitation terminals 36 of the transducer 33 into mechanical vibrations. Ultrasonic vibration thus supplied to the nozzle 18 helps to produce droplets of more uniform diameter at orifice 16.
  • the electrical energy needed to induce a charge and accelerate the droplets is supplied at terminals 22 of step-up transformer 20.
  • the secondary winding of transformer has a center tap 25 which is grounded.
  • the output terminals 24 of transformer 20 are connected through current-limiting resistors 26 to the electrode supporting rods 14 and 15, respectively.
  • the nozzle 18 is also grounded, keeping it and the mass of NaKrat a constant potential.
  • the electrode 8 adjacent to the orifice 16 induces a charge in the liquid metal droplets forming at the orifice 16.
  • the polarity of this induced charge is the reverse of the polarity on the inducing electrode 8.
  • electrode support rod 14 is positive as excited by transformer 20
  • the electrodes 8 and 10 are also positive with respect to ground.
  • electrodes 9 and 11 are negative with respect to ground.
  • the electrode 8 which is nearest the orifice 16 acts during droplet formation to repel positive charges from and to attract electrons to the orifice 16. While electrode 8 is positive, droplets are formed with a net negative charge. This charge then acts to repel the formed droplet from the negatively-charged orifice 16 and to attract the droplet toward electrode 8 by the force of attraction of opposite charges. A number of such droplets will be formed during one-half cycle of the alternating voltage supplied at the input terminals 22. These negativelycharged droplets will be attracted as a group to the electrode 8.
  • Electrode 9 is positive at this time and acts to attract the first group of droplets traveling between'electrode 8 and electrode 9. As the droplets are accelerated between electrodes there is an increase in the velocity of the droplets.
  • the spacing of the electrodes 8, 9, 10 and 11 is such that the electrical fieldgenerated thereby exerts a unidirectional accelerating force on the charged droplets in flight between electrodes.
  • the field is negligible as the polarity of the electrodes 8, 9, 10 and 11 changes and the droplets pass through the center of the electrodes 8, 9, 10 and 11.
  • the effect is a unidirectional force on the droplets by simulating an electric field traveling from the orifice 16 along the electrodes 8, 9, 10 and 11 at the same velocity as the droplets, with the increased spacing between electrodes 8, 9, 10 and 11 along the flight path compensating for the increase in velocity of the droplets as they are accelerated.
  • the electric field generated by electrodes 8, 9, 10 and 11 is similar to the traveling field used in linear accelerators as mentioned above.
  • the field when excited by an AC source is periodically oscillatory with respect to time at any one point between electrodes.
  • the space between electrodes 8, 9, 10 and 11 is related to the frequency and amplitude of the excitation voltage supplied to transformer 20 and the charge-to-mass ratio of the liquid metal droplets so as to produce the unidirectional force on the droplets.
  • the orifice 16 at which the droplets are formed, the electrodes 8, 9, 10 and 11, the electrode positioning brackets 12 and 13, and the lower portion'of electrode supporting rods 14 and 15 are enclosed in a bell jar 39 evacuated by a vacuum pump 38. It has been found that a pressure of 10- to l0 torr is suitable for success ful operation of the apparatus. The purpose of the vacuum is to prevent arc discharging between electrodes and between droplets and electrodes.
  • Current limiting resistors 26 are placed in series with the output terminals 24 of transformer 20 in order to minimize current flow if arcing does occur.
  • the center of the torroid of the first electrode 8 is placed 0.5 inch directly below the orifice 16; the distance between electrode 8 and electrode 9 is 1.7 inches; the distance between electrode 9 and electrode 10 is 3.0 inches; the distance between electrode 10 and electrode 11 is 4.5 inches.
  • acceleration was measured by high speed photographic methods. The camera viewed only the electrode 8, the electrode 9, and the orifice 16.
  • the nozzle 18 is a hypodermic needle one-half inch long with inside diameter of 0.011 inch and having a square end at orifice 16.
  • former 20 has an RMS voltage of 3,000 volts with respect to ground, which results in a maximum peak-to-peak voltage of 8,460 volts between electrodes.
  • the frequency of the voltage supplied to transformer 20 was fifteen cycles per second for the above-mentioned electrode spacing and applied voltage. Droplet sizes were of the order of onehalf millimeter in diameter.
  • the ultrasonic excitation supplied by transducer 33 was set at a frequency of twenty thousand cycles per second. For these values of system parameters, groups of droplets in numbers of five to ten per half cycle were accelerated to a velocity which, measured at the second electrode 9 was approximately 19.4 feet per second. From this, it is estimated that the terminal velocity was approximately 60 ft./sec.
  • the force exerted on the droplets When used as a thrust producer, for example as a propulsion engine for a rocket in space, the force exerted on the droplets would also be experienced on the apparatus as a whole in the opposite direction.
  • the thrust per unit time is approximately 8X10- pounds per droplet per second, and each droplet would have a terminal kinetic energy of 7.0)(10 ft.-lb.
  • the bell jar could, of course, be opened up at the bottom or simply eliminated.
  • this beam may be separated into two beams of homogeneous charge by establishing an electrical field perpendicular to the direction of travel of the beam and intersecting the beam.
  • deflecting plates 40 and 41 are provided. Plate 40 is biased by a battery 42 as a potential positive with respect to ground; plate 41 is biased by a battery 43 at a potential negative with respect to ground. Emerging from the field between plates 40 and 41 will be two divergent beams of homogeneously charged liquid metal droplets. The beam containing positively charged droplets is collected in a container or collector 44. Likewise, the beam containing negatively charged droplets is collected in a container or collector 46. Feed-through leads 48 connect high voltage output terminals 50 through the bell jar to the collectors 44 and 46. Voltage is built up between the terminals 50 limited only by the kinetic energy of the droplets used to overcome the repulsive force of the respective collectors 44 and 46.
  • Apparatus for producing alternately charged groups of accelerated liquid metal droplets comprising: a contained mass of liquid metal; means for forming droplets of substantially uniform diameter at a location on a surface of said liquid metal; an alternating voltage power source having a first output terminal of one polarity connected to said liquid metal; and a plurality of accelerating electrodes fixed in increasing spatial relationship along a line which includes the location of droplet formation, the first of said electrodes being connected to an output terminal of opposite polarity than said first output terminal and being located adjacent the location of droplet formation to induce a charge in said droplets as they are formed and to accelerate said droplets away from said location of formation and toward said first electrode, the remaining electrodes being successively connected to alternate polarities of said power source, the spacing between successive electrode being related to the frequency and amplitude of said power source and the charge-tomass ratio of said droplets so as to cause said droplets to experience a unidirectional accelerating force.
  • the droplet formation means comprises at least one elongated tubular duct having an orifice, said liquid metal passing through said duct to form into droplet at said orifice.
  • the apparatus of claim 2 further including ultrasonic transducer means coupled to said droplet formation means to induce ultrasonic vibrations therein.
  • Apparatus for producing alternately charged groups of accelerated liquid metal droplet comprising: a contained mass of liquid metal at ground potential; means for forming droplets of substantially uniform diameter at a location on a surface of said liquid metal; a source of alternating voltage power having two output terminals in phase opposition and symmetrical with respect to ground potential; and a plurality of accelerating electrodes fixed in increasing spatial relationship along a line which includes the location of droplet formation, the first of said electrodes being connected to one output terminal of said power source and being located adjacent the location of droplet formation to induce a charge in said droplets as they are formed and to accelerate said charged droplets away from said location of formation and toward said first electrode, the remaining electrodes being successively connected to alternate terminals of said power source, the spacing between successive electrodes being related to the frequency and amplitude of said power source and to the charge-to-mass ratio of said droplets so as to cause said droplets to experience a unidirectional accelerating force.
  • Apparatus for converting low voltage AC energy to high voltage DC energy comprising: a contained mass of liquid metal; means for forming droplets of substantially uniform diameter at a location on a surface of said liquid metal; an alternating voltage power source having a first output terminal of one polarity connected to said liquid metal; a plurality of accelerating electrodes fixed in increasing spatial relationship along a line which includes the location of droplet formation, the first of said electrodes being connected to an output terminal of opposite polarity than said first output terminal and located adjacent the location of droplet formation to induce a charge in said droplets as they are formed and to accelerate said droplets away from said location of formation and toward said first electrode, the remaining electrodes being successively connected to alternate polarities of said power source, the spacing between successive electrodes being related to the frequency and amplitude of said power source and the charge-to-mass ratio of said droplets so as to cause said droplets to experience a unidirectional accelerating force; means for establishing an electrostatic DC field substantially perpendicular to and intersecting the alternately charged beam of

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Particle Accelerators (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)
US446136A 1965-04-06 1965-04-06 Apparatus for producing a beam of accelerated liquid metal droplets Expired - Lifetime US3341720A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US446136A US3341720A (en) 1965-04-06 1965-04-06 Apparatus for producing a beam of accelerated liquid metal droplets
GB12249/66A GB1085485A (en) 1965-04-06 1966-03-21 Apparatus and method for producing a beam of accelerated liquid metal droplets
DE19661564965 DE1564965B1 (de) 1965-04-06 1966-04-02 Vorrichtung zur Erzeugung eines Strahles von elektrisch geladenen mehrfach beschleunigten F-lüssigmetalltropfen
FR56316A FR1474541A (fr) 1965-04-06 1966-04-04 Procédé et appareil pour produire un faisceau de gouttelettes accélérées de métal liquide
BE679106D BE679106A (pm) 1965-04-06 1966-04-06

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US446136A US3341720A (en) 1965-04-06 1965-04-06 Apparatus for producing a beam of accelerated liquid metal droplets

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BE (1) BE679106A (pm)
DE (1) DE1564965B1 (pm)
GB (1) GB1085485A (pm)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4181894A (en) * 1977-05-05 1980-01-01 Commissariat A L'energie Atomique Heavy ion accelerating structure and its application to a heavy-ion linear accelerator

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110207947A (zh) * 2019-05-08 2019-09-06 南京航空航天大学 液滴加速装置及方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2896083A (en) * 1953-07-27 1959-07-21 Beckman Instruments Inc Radio frequency mass spectrometer
US3191077A (en) * 1962-04-27 1965-06-22 Marks Polarized Corp Power conversion device

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE705879C (de) * 1938-10-26 1941-05-13 Aeg Elektrisches Entladungsgefaess zur Vielfachbeschleunigung von Ladungstraegern
US3122882A (en) * 1960-11-23 1964-03-03 Aerojet General Co Propulsion means
US3173246A (en) * 1963-03-12 1965-03-16 Carl T Norgren Colloid propulsion method and apparatus

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2896083A (en) * 1953-07-27 1959-07-21 Beckman Instruments Inc Radio frequency mass spectrometer
US3191077A (en) * 1962-04-27 1965-06-22 Marks Polarized Corp Power conversion device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4181894A (en) * 1977-05-05 1980-01-01 Commissariat A L'energie Atomique Heavy ion accelerating structure and its application to a heavy-ion linear accelerator

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DE1564965B1 (de) 1969-09-11
BE679106A (pm) 1966-09-16
GB1085485A (en) 1967-10-04

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