08/21/2014 at 05:44 •
For my engine prototypes I have decided to use a mixture of Argon and carbon since I have permission to use it. I am unsure of the effects carbon dioxide will have on the prototypes since carbon and oxygen may clog up the system by either forming solids or by reacting with electrodes.
For the final model (providing the Argon gas works as expected) I will see if I can get any other gas samples to use.
08/21/2014 at 05:42 •
alot of space companies don't really like volatile materials as ballast next to their primary payload for a number of reasons. one of them is that it isn't good to have news reports saying that their multi-million/billion dollar rocket or sattelite was proudly taken down by something the size of a stack of post-it notes. This means that that developers have a number of hoops to jump through in terms of flight readiness. One restriction is usually that there is a ban on all propellants but this can be overcome by proving that you cannot hurt/damage/disrupt/annoy the primary payload. One specific type of fuel that is typically involved is an inert propellant. This basically means that it doesn't react much with other elements or molecules under normal circumstances, which makes it a good candidate for use in my engine since it is likely that launch providers will not be upset over its chemical potential. The first place to look to find suitable fuel is the periodic table of elements.
All elements on the far right column are inert (helium, argon, neon etc) most of these (to my knowledge) are used industrially which means that they may be commercially availible for purchase. Helium is used in MRI machines and as a temporary fun, floating gas which is used to entertain children. Argon is (can be mixed with carbon dioxide) used in welding to ensure that the inside of the join isn't oxidised. Also neon is used in fancy signs outside some shops. Because of their commercial uses it will make it eaiser to obtain.
Many other elements either need to gain or lose electrons in order to be stable which leads on to the second place to look for inert fuel; molecules. these have an advantage since they sometimes take less room as a product than as individual reactants. For example, pure water will take up a much larger volume in its gaseous state than its liquid state since the vibrations of individual molecules is very fast. however one downside with using water is that the oxygen by itself may interfere with the electrodes and end up binding with the metal causing it to rust. If this was to be used, there may have to be expiriments to determine what mixture/coating of metal will be necessary to stop the oxidisation from occuring since it may hinder the conductivity of the electrodes. If a molecule based propellant is to be used, the effects of lone elements has to be considered.
probably the most important part about the fuel is that it has to have a low breakdown voltage. this refers to how strong the electrc field has to be in order to break the atom into an Ion. the componds with the lowest breakdown voltage will be favoured over those with higher values since it will take more power to split them up.
08/21/2014 at 01:26 •
I am going to split up this project into a number of phases to help make it easier to manage while also giving a narrow and clear focus for each phase.
1st phase: propellant research. Because of the processes needed with the engine, I will need to find a propellant that will split apart easily but will also remain stable in an un-altered state. I'm going to look into readily available inert gases such as helium and argon for easier reproduction. Containers will also be researched
2nd phase: electrode research. due to the high speed nature of the engine, spluttering may become an issue. this occurs when an electron approaches the electrode at high speeds and 'knocks off' part of the electrode, sending it into the exhaust flow. I will need to research and test the different types of conductive materials with different coatings to make sure the anode will still function while gas is still present. If a long lasting anode material is found, the engine can be re-purposed to function as a plasma engine.
3rd phase: power calculations/research. I will find out what load the typical small size battery can handle for my engine. producing a strong electric field will mean that the power supplied will have to be transformed into a high voltage supply to generate a large enough electric field to move the charged particles. other considerations include reducing electrical noise which may be generated by the movement within the electric field. This could also effect radio communications although I'll have to prove this.
4th phase: communications development; mapping out the PQ60 pinout to see which pins I can use to control the engine. I'll also have to either modify or create a new protocol which will be used to talk between the computer and engine.
5th phase: initial prototypes; I will make a vacuum chamber which will be used to simulate outer space. although I don't have the resources or knowledge to heat and cool the chamber, it will give a good indication as to how the engine will work in a airless environment. I will experiment with a variety of different electrode configurations to try and get an optimum thrust output. prototype engine enclosures may be made out of plastic since it is more accessible than other high strength materials. This is subject to change since I may find something better to work with. If I can find a 3d printer I'll manufacture the prototypes that way and publish .stl files online instead of publishing raw instrument drawings.
6th phase: enclosure research; this consists of finding materials that will work in the vacuum enviroment and will be tolerant to very large and fast changes in temperature. the chosen material will be used to create the semi-final prototype.
7th phase: final design of the engine itself. this marks the beginning of integration between the communications system, power inverters and the engine. small modifications can still be made at this point.
8th phase: evaluation of development and publication of Ion engine v1.0 this will still be developed beyond this point to ensure that any bugs and malfunctions are cleaned out.
features to add after first functioning model: thrust vectoring, addition of reaction wheels
08/18/2014 at 23:25 •
the method I will use to move propellant away from the engine is by accelerating charged particles from the area on and around a cathode to an electrode which attracts the negatively charged particles. the idea is that they maintain a portion of their momentum to move past the anode and continue their path without disrupting the engine