American Institute of Aeronautics and Astronautics1

Application of Active Electromagnetic Propulsion for SpaceExploration

Yung-Kang Sun1 and Rolando Castilleja2

Engineering Design and development Group, Arlington, Texas, 76013

Active electromagnetic propulsion is a creative innovation for future space exploration.During two years conceptual and experimental development, this innovation will changepropulsion history. Also, this innovation will bring the propellantless technology from fictionto reality in space exploration. NASA supported the Breakthrough Propulsion PhysicsProject from 1996 to 2002 in search of creative innovations in space transportation. Therequirements of this project are: (1) no propellant carried in the spacecraft; (2) themaximum transit speed created from this device during interplanetary flight; and (3) theenergy resource powered the propulsion system from the spacecraft system. At that time,engineers and scientists thought this project was not feasible, and violated basic principles ofspacecraft designs. However, young engineers and scientists continue to search the feasibilityand scientific potential in the new propulsion design for future space missions. In 2005, Ipresented the conceptual design of active electromagnetic propulsion using the Lorentz forcefrom the solenoid for interplanetary flight. In 2006, I presented the theory revised from myprevious presentation in detailed discussions of using electromagnetic force in the design ofdemonstration from the mathematical model. I also evaluated the sailing time of using thispropulsion system for space exploration from Earth to other planets in the solar system.Because engineers and scientists continuously share suggestions in this on-going research,active electromagnetic propulsion has been developed the mature mathematical model, andfulfilled the principles under the Newton’s Law in physics.

The theory of active electromagnetic propulsion is combined with the Lorentz force,impulse and linear moment from physics. When a charge is placed in an electric field, thatcharge experiences an electric force. The magnetic force will be generated when twoconditions are met: (1) the charge must move, for no magnetic force acts on a stationarycharge; and (2) the velocity of the moving charge must have a component that isperpendicular to the direction of the magnetic field. Based on those two conditions, themagnitude of the electromagnetic force is directly proportional to the magnitudes of thecharge and the component of the velocity perpendicular to the magnetic field. This is howthe electromagnetic force occurred, also known as the Lorentz force. The equation of the

Lorentz force is shown as )( BvqFrrr

×= or θsinqvBF = , where B is a vector thatrepresents the magnetic field, q is the total charge; v is a vector that presents the velocity ofthe charge, and F is a vector that shows the electromagnetic force. Next, the equation will be

substituted q and v to I and Lc because oft

qI = and vtLc = . The new equation will be

written as θsinBILF c= . In this innovation, the solenoid will be used in the design of

electromagnetic propulsion. Assume dnLc π= and IL

nB 0µ= , where Lc is the total

1 Director, Engineering Design and Development group, 701 West Mitchell Circle, Apt. #333, Arlington, Texas76013, AIAA Member.2 Student, Department of Mechanical and Aerospace Engineering, 9402 Lenel Place, Dallas, Texas 75220, AIAAStudent Member.

43rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit 8 - 11 July 2007, Cincinnati, OH

AIAA 2007-5127

Copyright © 2007 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

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length of the coil on the solenoid; d is the diameter of the solenoid; n is the total turns of thecoil; I is the current, 0µ is the permeability of free space (4π×10-7 T*m/A), and L is the

length of the solenoid. Now substituting Lc and B into the equation, and the formula of the

maximum electromagnetic force will beL

ndIF

220πµ

= as θ=90º. This equation shows

design factors of building this propulsion device, such as the current, the length of thesolenoid, the diameter of the solenoid, and turns of the coil. Figure 1 shows the relationshipbetween the propulsion force and turns of the coil. Figure 2 shows the relationships betweenthe propulsion force and current. Figure 3 shows the relationship between the propulsionforce and the diameter of the solenoid, and figure 4 shows the relationship between thepropulsion force and the length of the solenoid.

To provide the velocity for the spacecraft in the space exploration, the principles ofimpulse and linear moment are applied in this innovation. The electromagnetic force attractsthe moving iron bar on the middle of the solenoid, where the moving bar is floating in thespace due to no gravity. The moving iron bar will hit the device’s hull and stick together asthe one system when the spacecraft is not moving on the orbit. This technique provides theinitial velocity for the spacecraft in interplanetary flight. The mathematical model of the

spacecraft velocity provided from this innovation is shown asLmM

tndIV

s )(

220

+=πµ

, where Ms

is the mass of the spacecraft; m is the mass of the moving iron bar inside the propulsionsystem; V is the velocity of the spacecraft, and t is the time of inputting direct current in thedevice. This innovation provides the high velocity for interplanetary flight in the spaceexploration. For example, this device will provide 394.74 m/s to the 10 kilo ton spacecraftwith only 10 ampere, and 1 meter diameter, 1 meter length and 100,000 turns of coil on thesolenoid in one second. Figure 5 shows the illustration of this innovation based on themathematical model.

This innovation is a breakthrough in space propulsion technology, and will thus be ofvalue in developing scientific exploration goals for NASA’s Crew Exploration Vehicle. Thisinnovation has three significant advantages in the application of space propulsion. First, thisdevice does not need any propellant. It only uses the electricity in the spacecraft to producevelocities for the spacecraft in the exploration. Astronauts only need to operate this device tocontrol the direction and magnitude of the direct current. This device can accelerate anddecelerate the speed during the space flight. This innovation will make the space explorationsafer and reliable because of no dangerous chemical propellant carried on the spacecraft.Next, this innovation does not have complicated moving components. This significantadvantage reduces 50% of the weight in the spacecraft based on the Apollo spacecraftdeveloped in the 1960s. Also, this innovation will help contractors reduce the budget indeveloping new powerful, but conventional engines. According to the simple calculation, thisdevice will propel 10 kilo ton spacecraft in the space flight. It will help engineers developgiant spacecrafts for future’s space missions. Finally, this device produces the high velocityto the spacecraft in a short time during interplanetary flight. In my previous discussion ofthe paper, this system produces around 395 m/s in the space travel in one second based onthe demonstration. This significant contribution will only take astounds less than 24 hoursflight from Earth to the Moon, and less than 30 days to Mars using the fast orbit transfertechnique. It will change the traditional concept of planning space travel, and more touristswill be able afford the price. This paper introduces the theory and mathematical model ofthis innovation in space propulsion and the significant contributions of this innovation forfuture space exploration.

American Institute of Aeronautics and Astronautics3

Fig1. The relationship between the magnetic force and turns of coil.

Fig. 2 The relationship between magnetic force and current in amp.

Fig. 3 The relationship between the magnetic force and the diameter of the pole in meter.

American Institute of Aeronautics and Astronautics4

Fig. 4 The relationship between the magnetic force and the length of the pole in meter.

Fig. 5 The illustration of the Device of the Active Electromagnetic Propulsion System.

References

1 “NASA Breakthrough Propulsion Physics (BPP) Project,” URL: http://www.grc.nasa.gov/WWW/bpp/ [cited 25August 2004].

2Lyons, V., Gilland, J., and Fiehler, D., “Electric Propulsion Concepts Enabled by High Power Systems for SpaceExploration,” 2nd International Energy Conversion Engineering Conference, Providence, Rhode Island, 2004.

3Sun, Y., “Design Concept of Electromagnetic Propulsion for Interplanetary Flight,” 41st AIAA/ASME/SAE/ASEE JointPropulsion Conference, Tucson, Arizona, 2005.

4Sun, Y., “Design Theory of Active Electromagnetic Propulsion for Interplanetary Flight,” AIAA student Conference,College Station, Texas, 2006.

NomenclatureB = magnetic fieldd = diameter of solenoidF = magnetic forceI = currentL = length of the solenoidLc = length of the coil on the solenoid

Iron Bar

Solenoid coil with the direct current from the power generator

Propulsion Device Hull

Hollow Tube

Moving direction of the iron bar

Moving direction of the propulsion system and the spacecraft after hit the iron bar on the hull and stick together

d

American Institute of Aeronautics and Astronautics5

n = turns of coilq = total charget = timev = velocity of the iron moving component inside the deviceθ = degreeµ0 = permeability of free space (4π×10-7 T*m/A)m = mass of the iron moving component inside the deviceM = mass of the spacecraftV = velocity of the spacecraft

I. IntroductionASA supported the Breakthrough Propulsion Physics Project from 1996 to 2002 in search of creativeinnovations in space transportation. The requirements of Breakthrough Propulsion are:

1. The breakthrough propulsion system does not carry any propellant mass.2. The breakthrough propulsion system reaches the maximum possible transit speeds during interplanetary

flight.3. The breakthrough propulsion uses the power provided from the spacecraft during interplanetary flight.

Based on the requirements, topics of interest include experiments and theories regarding the coupling of gravity andelectromagnetism, the quantum vacuum, hyper power fast travel, and super luminal effect. Because the propulsiongoals are presumably far from fruition, a special emphasis is to identify affordable, near-term, and credible researchthat could make measurable progress toward these propulsion goals.1

In the year of 1998, Mick T. French proposed a new idea of applying non-zero momentum to propel thespacecraft. This is the first conceptual design for non-propellant propulsion technology. In the year of 2004, Gilland,Fiehler and Lyons introduce Magnetoplasmadynamic (MPD) Thrusters and Pulsed Inductive Thruster (PIT) at the2nd International Energy Conversion Engineering Conference.2 Using the electromagnetic force to accelerateneutrally charged plasma to high velocities is the basic concept for two thruster designs. In the paper, authorsannounced that the specific impulses of these thrusters could reach 1000 to 10, 0000 seconds. However, thistechnology needs the propellant to accelerate the spacecraft. In the description, the spacecraft needs to carry thepropellant, and this does not meet the requirement.

In the technological classification, two types of electromagnetic propulsion system will be applied in futureinterplanetary flights. One is passive electromagnetic propulsion and the second is active electromagneticpropulsion. In the year of 2005, I presented the basic concept of the active electromagnetic propulsion type at the41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference.3 This paper concentrates on the active electromagneticpropulsion type. The purpose of this paper is to introduce another method that is based on the Lorentz force, impulseand momentum in physics. This design concept of electromagnetic propulsion is different from other methodspresented in previous conferences. The main difference is that this design does not require any propellant massduring interplanetary flight. This is the best candidate to sail in space that has little gravitational effect. Thefollowing sections discuss the design theory, the relations among factors of the electromagnetic propulsion design,and advantages to the design. At the end of this paper, some technical suggestions of this electromagnetic propulsiondesign will be discussed.

II. Theory of Active Electromagnetic propulsionWhen a charge is placed in an electric field, that charge experiences an electric force. The magnetic force will be

generated when two conditions are met:1. The charge must be moving, for no magnetic force acts on a stationary charge.2. The velocity of the moving charge must have a component that is perpendicular to the direction of the

magnetic field.Based on those two conditions, the magnitude of the electromagnetic force is directly proportional to the magnitudesof (1) the charge and (2) the component of the velocity perpendicular to the magnetic field. This is how theelectromagnetic fore occurred, also known as the Lorenz force. Because of these factors, the relationship betweenthe magnitude of the magnetic field and the velocity of the moving charge is formulated as:

)( BvqFrrr

×= or θsinqvBF = (1)

In equation (1), B is a vector, and its direction can be determined by using a small compass needle to find themagnetic force direction.

N

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From the experiment of the physics of the magnetic field in the electric field, a charge moving through amagnetic field can experience a magnetic force. Since an electric current is a collection of moving charges, a currentin the presence of a magnetic field can also experience a magnetic force. In the laboratory experiment, the directionof a current affects the direction of the magnetic force. This phenomenon helps propulsion engineers to apply in theelectromagnetic propulsion design to control the flight directions in interplanetary flight. Support the time required

for the charge to travel the length of the wire, equation (1) will be substituted I and v as

θsin))(( Bvtt

qF = (2)

Becauset

qI = and Lc=vt, equation (2) is formulated as

θsinBILF c= (3)

Equation (3) shows that the maximum electromagnetic force occurs if the wire is oriented perpendicular to the field

( °= 90θ ). The new equation from equation (3) will be presented as

BILF c= (4)

In the design of the electromagnetic propulsion system, the solenoid is the best choice to manufacture for thisdevice of the electromagnetic propulsion. The solenoid can gain much electromagnetic force for the propulsion inthe interplanetary flight. A solenoid is a long coil of the wire in the shape of a helix. The field inside the solenoidand away from its end is nearly constant in magnitude and directed parallel to the axis. The magnitude of themagnetic field in the interior of long solenoid is

IL

nB 0µ= (5)

Assume the length of the solenoid is

dnLc π= (6)

When substituting B and cL into equation (4), the new equation of the electromagnetic force in the solenoid type

design will be presented as

L

ndIF

220πµ= (7)

To provide the velocity for the spacecraft in the space exploration, the principles of impulse and linearmomentum are applied in this innovation. The electromagnetic force attracts the moving iron bar on the middle ofthe solenoid, where the moving bar floats in the space. The moving iron bar will hit the device’s hull and sticktogether as the one system when the spacecraft is not moving in orbit. This technique provides the initial velocity forthe spacecraft in interplanetary flight. The relationships among the electromagnetic force, the moving iron part andthe spacecraft are shown as:

VmMmvFt )( +== (8)

The mathematical model of the spacecraft velocity provided from this propellantless propulsion system is shown as

LmM

tndIV

s )(

220

+=πµ

(9)

This innovation provides the high initial velocity for interplanetary flight in a short time in the space exploration.For example, this propulsion will provide 394.74 m/s to propel the 10 kilo ton spacecraft with only 10 ampere, onemeter diameter, one meter length and 100,000 turns of the coil on the solenoid in one second.

Equation (7) will be applied to design the device of the electromagnetic propulsion system with the solenoidtype, and discuss the relationships among the electromagnetic force, the length, the diameter, the turns of the coil ofthe solenoid pole, and the current with figures in the following session.

III. Discussions of Conceptual Designs of Active Electromagnetic PropulsionEquation (7) shows that the length and the diameter of the solenoid, the current and the turns of the wire are

important factors to affect the force scale of electromagnetic propulsion. The following sections discuss the

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relationship between the electromagnetic force and the turns of the coil, the current, the diameter of the solenoid andthe length of the solenoid. Assume the material of the wire and the solenoid does not generate any heat from thecurrent and the resistance is approached to zero in this propulsion.

A. The Relationship between the Electromagnetic Force and Turns of the Wire on the CoilEquation (7) shows that the relationship

between the electromagnetic force and turns

of the wire on the coil is 2nF ∝ . This is avery important factor to design the device ofthe electromagnetic propulsion system,because the electromagnetic force will beincreased by the square of the turns of thewire on the coil. To generate the largerelectromagnetic force to propel thespacecraft in the interplanetary flight,engineers can increase the turns of the wirein the limited length of the solenoid coil.This technique is the simplest way toincrease the electromagnetic force based onrecent technology. Figure 1 shows therelationship between the electromagneticforce and the turns of the wire in thesolenoid coil.

B. The Relationship between the Electromagnetic Force and CurrentEquation (7) shows that the relationship

between the electromagnetic force and turns of

the wire on the coil is 2IF ∝ . That meansthe electromagnetic force will be increased bythe square of the current. This is also a veryimportant design factor for the device of theelectromagnetic propulsion system, becauseengineers can increase the current that isgenerated from the power plant in thespacecraft. Engineers can apply thisrelationship to design the device more simplyin the electromagnetic propulsion system. Togenerate the larger electromagnetic force topropel the spacecraft in the interplanetaryflight, engineers can increase more current onthe solenoid. This technique is another simplemethod to increase the electromagnetic force,because the current can be generated from thepower plant of the spacecraft. Figure 2 showsthe relationship between the electromagneticforce and the current in the solenoid coil.

C. The Relationship between the Electromagnetic Force and the Diameter of the SolenoidEquation (7) shows that the relationship between the electromagnetic force and the diameter of the solenoid

is dF ∝ . That means the larger diameter of the solenoid produces the more power of the electromagnetic force.

Figure 1.The relationship between the magnetic force and turnsof coil.

Figure 2. The relationship between magnetic force and current inamp.

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From this relationship, engineers canincrease the diameter on the solenoid. Togenerate the larger electromagnetic force topropel the spacecraft in the interplanetaryflight, engineers can increase the diameter ofthe solenoid. However, the result will not besatisfied because the relationship betweenthe electromagnetic force and the diameter islinear. This method is not efficient ifincreasing the diameter of the solenoid.Figure 3 shows the relationship between theelectromagnetic force and the diameter ofthe solenoid.

D. The Relationship between theMagnetic Force and the Length of theSolenoid

Equation (7) shows that the relationshipbetween the electromagnetic force and the

length of the solenoid isL

F1

∝ . That

means the longer solenoid produces lesspower from the electromagnetic force. Inorder to increase the electromagneticforce, engineers need to make the lengthof the solenoid short, so that theelectromagnetic force will be increased ininterplanetary flight. However, the shortlength of the solenoid is very difficult tomanufacture and the technique is not veryefficient. From figure 4, the plot showedthat the short length of the solenoid only

produces N5105.5 −× . Figure 4 shows

the relationship between theelectromagnetic force and the length ofthe solenoid.

E. The Conceptual Design of the ActiveElectromagnetic Propulsion System

From section (1) to (4), the authorconcludes that the electromagnetic force will depend upon the length, the diameter and the turns of the wire on thelimited length of the solenoid pole, and the current that applied on this device. This device uses the direct current toattract the moving iron bar to provide the initial velocity to the spacecraft. Space pilots can reverse the direction ofthe direct current to change speeds and directions in interplanetary flight. The direct current is from the powergenerator in the spacecraft. Figure 5 shows the design concept of the device of the electromagnetic propulsionsystem that is based on equation (7) and equation (9).

Figure 3. The relationship between the magnetic force and thediameter of the solenoid in meter.

Figure 4. The relationship between the magnetic force and thelength of the Solenoid in meter.

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Figure. 5 The Design Concept of the Device of the Electromagnetic Propulsion System.

IV. Advantages of Active Electromagnetic Propulsion for Interplanetary FlightIn the year of 2005, I discussed advantages and barriers to active electromagnetic propulsion at the 41st

AIAA/ASME/SAE/ASEE Joint Propulsion Conference. After the continuous research of active electromagneticpropulsion in the space environment, more advantages will be discussed when selecting active electromagneticpropulsion for interplanetary flight in future missions. Also, the barriers of active electromagnetic propulsion thatdiscussed at the 41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference can be solved because of the specialenvironment in space. Here are the reasons that choosing the electromagnetic propulsion is superior to other types ofpropulsion systems:

1. The active electromagnetic propulsion system has the simple structure based on the discussion of theconceptual design in the previous section. This significant advantage helps manufactures to reduce thebudget to build and maintain the propulsion system. Also, this innovation does not carry any propellantmass. Mission crews will have a safe interplanetary flight because of no dangerous chemical propellantinside the spacecraft.

2. The active electromagnetic propulsion system performs the high vaccum impulse specific and a widerange of thrust ranges compared to conventional and advanced propulsion technologies for space flight.The ideal space propulsion system should have a wide range of thrust and highest specific vacuumimpulse (Isp) for interplanetary flight. The hihest specific vacuum impulse can reach 6,000 secondsfrom the electrostatic ion propulsion system. However, the thrust from this system is too low to propelsmall unmanned space probes for planetary missions. The active electromagnetic propulsion system hashe infinite specific vacuum impulse because no weight rate of propellant flow occurs in this system.Also, this innovation provides various thrust range, because this system changes the range of the directcurrent to produce different thrusts. Table 1 shows the comparison of performances and operatingcharacteristics for space propulsion system from conventional technologies and this innovation.

Table 1. Comparison of Performances and Operating Characteristics

Type Energy Vacuum Impulse Specific(Isp)

Thrust Range (N)

Solid motor Chemical 280-300 610550 ×−Cold gas High pressure 50-75 0.05-200

Electro thermal resistojet Chemical 150-700 0.005-0.5Arc jet Resistive heating h~0.9 450-1500 0.05-5

Electrostatics ion Electro arc heating h~0.3 2000-6000 5.0105 6 −× −

Electromagnetic MPD Magnetic 2000 25-200

Iron Bar

Solenoid coil with the direct current from the power generator

Propulsion Device Hull

Hollow Tube

Moving direction of the iron bar

Moving direction of the propulsion system and the spacecraft after hit the iron bar on the hull and stick together

d

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Pulsed plasma Magnetic 1500 005.0105 6 −× −

Pulsed inductive Magnetic 2500 2-200Active electromagnetic

non-propellant propulsionElectromagnet Infinite 0 and above

Liquid Chemical 300-450 61055 ×−

3. The active electromagnetic propulsion provides enough escape velocities for the fast orbital transfer toreduce the flight time. The fast orbital transfer method can reduce the traveling time in interplanetaryflight. However, the barrier of using this method is that the spacecraft must use much propellant toproduce the enough initial velocity to sail other planets. It is not benefit of using the fast orbital transfermethod with conventional propulsion systems. The active electromagnetic propulsion system producesenough thrust to propel the giant spacecraft, and space pilots can accelerate enough escape velocities ina short time. With this innovation, mission crews can reach to the moon within 24 hours, and withinthree days to Mars. Table 2 shows the flight time of using this innovation with two-meter diameter onemeter long, 1,000,000 turns of the coil and 20 ampere on the device in one second.

Table 2. Flight Time with Active Electromagnetic Propulsion

Planet Traveling TimeMoon 0.2 hourMars 3 days

Jupiter 14 daysSaturn 25 daysUranus 51 daysNeptune 79 days

Pluto 104 days

V. Conclusion and Future WorkThe active electromagnetic propulsion system is worth developing for future planetary flights. The previous

section discussed the outcomes in the developments of active electromagnetic propulsion. Here are somesuggestions for active electromagnetic propulsion in future space missions.

First, active electromagnetic propulsion provides high thrust and specific impulse in space. In the near-termspace mission, this innovation is the best candidate for unmanned space probes and robotic space missions. It savestime and budget for planetary explorations in the solar system, and fulfills NASA’s new requirements for spaceexploration plans. This innovation will thus be of value in developing scientific exploration goals for NASA’s CrewExploration Vehicle if on-board computers can modify the suitable thrust for astronauts in interplanetary flight.

Next, we found this innovation has a minor barrier because it produces the high impact. This will damage thehull of the device. In order to solve this problem, the new material or device will be developed to absorb high impactin the operation during interplanetary flight.

Finally, space pilots can control flight directions and speeds easily during interplanetary flight. Traditionally,space pilots needed to control rockets to keep correct flight paths and directions in conventional spacecrafts. Thisinnovation helps space pilots operate the spacecraft without controlling complicated equipments duringinterplanetary flights. Space pilots only reverse directions of the direct current to reduce speeds, or change flightpaths. This innovation is more convenient to use for space missions compared to current propulsion technologies.

AcknowledgmentsThe author would like to thank Mr. Kenneth Starcher, the director of Alternative Energy Institute at West Texas

A&M University, for his kind suggestions in my research during the discussions. Also, the author would like tothank Dr. Tachung Yih, Vice Provost and Professor of Engineering at Oakland University for his financial supportto build the small experimental prototype based on the theory of this paper. In addition, the author would like tothank Mr. Brandon Shippey, graduate student of Aerospace Engineering, Mr. Rolando Castilleja, Tarrant CountyCollege student and Mr. Kurata Hironari, undergraduate students of Mechanical and Aerospace Engineering at theUniversity of Texas at Arlington, for their variable technology advises and assistances in this creative research. At

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the end of this paper, the author would love to appreciate Mrs. Lisa Berry, my advisor and learning specialist atSOAR University Tutorial at the University of Texas at Arlington, for her positive suggestions in this paper.

References1 “NASA Breakthrough Propulsion Physics (BPP) Project,” URL: http://www.grc.nasa.gov/WWW/bpp/ [cited 25

August 2004].2Lyons, V., Gilland, J., and Fiehler, D., “Electric Propulsion Concepts Enabled by High Power Systems for Space

Exploration,” 2nd International Energy Conversion Engineering Conference, Providence, Rhode Island, 2004.3Sun, Y., “Design Concept of Electromagnetic Propulsion for Interplanetary Flight,” 41st AIAA/ASME/SAE/ASEE Joint

Propulsion Conference, Tucson, Arizona, 2005.