Visualization of Micro-Electric Thrusters

Virginia Polytechnic Institute and State University

Scientific Visual Data Analysis and Multimedia

Project Contract

Principle Investigator:

Ryan Stillwater


Conventional spacecraft propulsion uses chemicals to propel itself. The most common types are mono-propellant and bi-propellant. Mono-propellant systems are very simple, and can me likened to a bottle of soda. When you open a bottle of soda some carbon dioxide escapes out of the top of the bottle. The releasing of gas by opening a nozzle will create enough thrust to move a spacecraft. Bi-propellant uses 2 different chemicals to create higher pressures/temperatures, which forces the gas out of the nozzle faster than mono-propellant thereby creating more thrust. This type of propellant is the one most people are familiar with, especially if you have ever seen a space shuttle launch. The orbiter's main engine produces thrust by mixing liquid hydrogen and liquid oxygen. All chemical propulsion systems produce relatively large amounts of thrust, but can only operate for a short period of time before burning out and are typically about <60 percent efficient.

The other main type of spacecraft propulsion are electric engines which, as their name suggests, use electricity to produce thrust for a spacecraft. The most well known electric thruster is the ion engine, which was "field" tested on the Deep Space 1 spacecraft. This type of engine works is by accelerating the gas it expels to many times the speed of a bi-propellant system. The noble gas, such as Xenon, are ionized by bombarding them with electrons. Then the ionized gas is pulled towards an electrified grid at the back of the engine. The ions pass through the grid and out into space. Since the gas from an ion engine is traveling much faster rate than the gas chemical rocket you get more energy per molecule or "more bang for your buck." 

The problem come in with the fact that considerably fewer molecules per second are released. Ion engines can be about 80 percent efficient, but they will produce only a fraction of the thrust per second that a chemical rocket will produce. Luckily there is the snowball effect. A small snowball starting to roll at the top of a large hill can result in a large snowball at the bottom of that hill, this is the same thing that results with electric thrusters. A small amount of force produced over a long period of time results in the same or larger impulse that a chemical rocket gives. So if you can spare the time you can get where you want to go using far less fuel. At around $10,000 per kilogram in launch costs alone the money saved can often out way the extra time spent.

The standard design procedure for engines is design, build, test, and repeat. Electric spacecraft engines are tested using vacuum tanks. Vacuum tanks, especially very low pressure vacuum tanks are expensive to maintain and operate. In the case of the engine lifetime test the engine and the tank are running nearly constantly for months. The price of testing alone makes the designing of electric spacecraft engines prohibitively expensive, especially on a university budget. A computer can be used to simulate the engine and its testing at a much lower cost. The simulation can also be evaluated at a level of detail that is impossible in conventional testing. This project involves the visualization of the simulation of a micro electric thruster known as a hollow cathode thruster or HCT.



The main objective of this project is to learn how to use the visualization tools available to aid in the understanding to the simulated HCT.

The methodology involved will be:

  1. Develop a desktop model HCT and vacuum tank
    a. Create a meshed CAD image of the HCT and the vacuum tank.
    b. Merge the simulation data with the meshed geometry. 
  2. Convert the desktop model into an immersive model capable of being displayed in the CAVE.
  3. Summarize the project into a multimedia/web presentation and a CAVE presentation in order to effectively communicate the results to the class and future classes.



Hardware:  Sun workstation, IBM Desktop, Macintosh Desktop

Software: Diverse, 3D Studio Max, Macromedia Flash, Matlab, C++, CAPVte, and Microsoft Frontpage