Electrostatic Propulsion Explained

Electrostatic Propulsion System

The electrostatic propulsion system uses static electric fields to guide and accelerate ions to provide thrust. Like before with my electromagnetic propulsion page, I will try to explain the system in a Simple way to a more advanced way.


Simple Conceptual Explanation:


First, I have listed the main components for operation above in the diagram:


1. Ionizer - A device that applies large electric fields to gases and breaks them down into a plasma.
2. Accelerating grid/grids -  A system of grids that hold a charge and provide an electric field to accelerate ions.
3. Electron emitter - A device that emits electrons in order to neutralize the system.


From just reading the description of what the components do we can get a good idea of what's going on. It, like the electromagnetic propulsion system, is not too complicated to understand. In order to have an electric field provide the system with an accelerator we need ions (positively charged particles) as our mass to be accelerated. It is the job of the ionizer to ionize gases before entering the chamber or nearing the accelerating grid. It does this, lets say for my particular system, by bombarding the gases with fast moving electrons that collide with the gas atoms giving them tremendous energy per unit mass. This energy density bumps the gas into its next state and creates a plasma. The plasma is positively charged because it has lost a valence electron or two or maybe even three. This loss of negative charge (electrons are negatively charged) gives the atoms a positive net charge. This net charge now will follow the electric field lines provided by the accelerating grid/grids and be expelled out the back of the propulsion system. But that's not the end of the story. We still need to make sure that all charges are accounted for. We have been exhausting plenty of ions (positive charges) and now have a propulsion system that has a net charge that is negative. This is where the electron emitter sometimes called an electron gun comes in. Its job is to neutralize the propulsion system by getting rid of excess negative charges. Let's say for my particular system it does this by passing a current through a tungsten wire generating high energy density and causing the metal to release some of its electrons (negative charges). So now we have propulsion and neutralization!


More Quick Explanation (for those that know about basic electric and magnetic principles):


The diagram drawn about shows a cross sectional view of the propulsion system. The main operating components are numbered:


1. Ionizer
2. Accelerating grid/grids
3. Electron emitter


An electrostatic propulsion system uses a charged accelerating grid to propel ions produced by the ionizer. It them neutralizes the now net negatively charged system by expelling electron out the electron emitter.


Design Notes:


1. When designing the system it is just as important to research the optimal gas that can be used for many reasons. The most important part of the gas properties would be the ionization energy of the first and probably the second electron. Some gases will release electrons when provided with less energy then other gases. This is obviously important for efficiency's sake.




I try my best to make the information provided as accurate as possible. If you spot a mistake or disagree with what I have wrote please let me know. Thank You.