The Fellowship Application of Woodrow Wilson

Discovered in 1879 by Edwin Hall, the Hall effect is the production of a voltage difference across an electrical conductor transverse to an electric current in the conductor and to an applied magnetic field perpendicular to the current. This happens when the magnetic field exerts a transverse force on the moving charges(positive and negative) tending to push them to one side of the conductor. Simply put, the Hall effect is an extension of the Lorentz force which describes the force exerted on a particle moving through a magnetic field. The Hall effect refers to the situation created when the Lorentz force acts on moving electrons in a semiconductor, causing a difference in electric potential to develop between the two sides of the conductor; called the Hall Voltage. This comes to play in a Hall Effect Thruster when, on heating up gas to ionization to form plasma, the charges on the plasma are all accelerated by a strong magnetic field being directed outside to provide the needed thrust. Ionization is the process of charging an electron. Plasma is deemed to be the fourth state of matter, as it exists everywhere, and is electrically neutral which means all charges add up to zero. For any type of electronic propulsion to happen, the base has to be plasma as it conducts electricity and is affected by both electrical and magnetic fields. A hall effect thruster works by using electric fields to accelerate positively charged propellant ions to create thrust. The most commonly used propellant is Xenon as it has a high atomic weight and low ionization potential. Without magnetism, the electrons are not useful for thrust and thus the need to trap them with a magnetic field, hence the hall effect. In recent groundbreaking results from NASA on the X3 ion thruster, the hall effect is maximized in the creation of a three grid system that utilizes plasma moving at high velocities to provide thrust that will hopefully allow for manned expeditions to Mars. As part of NASA’s NextStep program, the X3 is a new rocket engine that is entirely electric. It has greater efficiency than the chemically propelled rockets but generates very low thrust which means slower acceleration.

To increase the thrust, scientists have come up with an engine for the X3 that, instead of one channel, has three channels which generate higher power, which means higher thrust and therefore higher acceleration. However, if a higher ratio of thrust produced to propellant used is needed, the ion thruster is much more effective compared to the Hall effect thruster. To this end, innovators at NASA’s Glenn Research Center have come up with a system that takes advantage of both the ion and hall effect thrusters to create what is known as a dual thruster propulsion system. This electric propulsion device offers the ability to switch a spacecraft’s propulsion system to either Ion thruster mode or hall effect mode depending on whether the principle need is efficiency or thrust power. This system has increased efficiency and increased power. Based on these remarkable findings, it is clear that there exists what it takes to move space exploration to the next level. In this line, I intend to use the same rationales and results from all these projects in developing a much more efficient system which will be lighter than the X3 version. Project and design The X3 engine weighs 500 pounds and this means, even though the acceleration of the rocket is higher than in other models, the engine is still not living to its full potential as a higher mass means lower acceleration. If we are to ever live on Mars, we need to be able to cover the distance to and from Mars in a short time. To this end, I propose a lighter system that magnetizes the path of the rocket using tiny magnets suspended in a liquid. This means that only concentrators are attached to the hull of the rockets and the system of permanent magnets is done away with.

Permanent magnets are disadvantageous in that the field cannot be shut down during the thruster start-up; when the electron density is low and with a strong field the initiation of the ionization cascade is difficult to establish (Warner, 2007). This disadvantage is overcome by the use of electromagnetic coils, which unfortunately have increased ohmic heat dissipation which adds to the thruster operational heat dissipation during the ionization process. The higher temperatures are an important problem for both permanent magnets and electromagnetic coils. In my system though, the heat problem is entirely eliminated as the magnetic field producers are entirely independent of the system. Academic and Scientific Background I have long been interested in Space Science and have had notable achievements to this end. Last year, I was the shadow to the lead scientist on the Kenya Space Agency, Dr. John Kimani, and learned so much about the benefits of a space agency. I have also written a research paper on how using wireless chargers in rockets can help scale large distances. However, my model utilized both wireless chargers and liquid propellants which would be turned on after crossing the magnetosphere. The project I have outlined today is one I intend to pursue under the expert tutelage of professors like Prof. Ibrahima Bah at John Hopkins. If I was to get the Woodrow Wilson Research Fellowship, it would help me obtain the necessary resources to develop both of my projects.