Project
| # | Title | Team Members | TA | Documents | Sponsor |
|---|---|---|---|---|---|
| 10 | Device for Producing and Dropping Metal Particles with Consistent Charge Area Award: Courage |
David Rubrecht Logan Marlow |
Sam Sagan | design_document0.pdf final_paper0.pdf presentation0.pptx proposal0.pdf |
|
| The task here is the first half of a larger project, the electro-dynamic levitation of charged metal particles. The goal is a single unit that both holds a moderate amount of metal powder, charges some of the metal powder inside, and reliably drops metal particles with consistent charge. The container shape will be cylindrical, with a conical base pointing towards the floor. The tip of the cone will be cut away, and replaced by a horizontally placed cylinder that seals the base yet can be rotated reliably (most likely with a servo or stepper motor). The rotating cylinder will have small notches in it to catch powder and allow the captured particles to be dropped from the overall container. Note, the container is plastic, or otherwise electrically insulated. In terms of charging, 2 methods particularly come to mind. My current favorite is charging by induction. A electrically insulated lead with a negative voltage applied to it (relative to some ground) will be inserted into the center of the container (either as a flat circle with the normal vector pointing downwards or a sphere). From there, the overall charge that is naturally present in the metal powder is separated, with the positive charge moving towards the lead and the negative charge spread throughout the edges of the container (most notably, the tip of the cone). Once a particle is removed via the rotating cylinder, the net charge on the removed particle will be negative. This method allows for minimal controls, but comes with the caveat of a lower maximum charge per particle. Along the lines of the a method Sam and I discussed, by wrapping the container on a layer of foil (or the rotating cylinder is metal and coated in some type of plastic) and holding that foil as the ground, the whole container can act as a capacitor. A non-insulated lead is inserted into the container (in contact with the metal powder) and has a negative voltage applied to it (relative to the exterior foil, at least). This method is the easiest to examine theoretically and allows for a higher maximum charge per particle (as charge is not dependent on the natural charge of the metal powder). However, my suspicion is a small amount of controls will be needed here, as I suspect the electric fields from the exterior foil or otherwise fringes will interfere will the second component to the larger project. This can be easily overcome by simply switching off the capacitive charging circuit during the time of dropping. Overall, this project encompasses a power, charging, driver and controls circuit. Microcontroller programming will be necessary for controlling the status of the charging circuit and the driving of the servo/stepper motor. Once this project is completed, we will move on to the larger goal. PS: To measure the charge on a dropped particle, my current idea is to pinch a particle into a ammeter that is tied to ground. By taking the integral over the ammeter, the total charge can be calculated. There are probably other ways of measuring absolute charge, but this method seems simple. |
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