A new design

I tried rotating the probe above the lower electrode to position it directly above the cloud, but now with the greater distance between probe and cloud I was unable to see any movement of the cloud at all. If we were able to generate a pulse of more than 210V we would probably be able to induce a strong wave in the cloud, and maybe even a shock, but it would be hard to find a stronger waveform generator or put together a system for pulsing our standard power supply in the time I have left.

So, I'm done with the probe for now. I decided on a design for the nozzle that will let me control its height without opening the vacuum chamber. I made a little mock-up of it for my mentor:

It's pretty simple: the plate hangs by a few pieces of wire from a rod, which can be rotated to wind the plate up or down. The rod sticks through two openings of the chamber and is sealed by a Wilson seal that allows the rod to rotate while remaining sealed. In the actual design, the wire will be replaced by nylon line (fishing line), the metal tube replaced by a plastic rod (so as to be electrically isolated), and the plate will be a 1mm-thick steel disc. My mentor was skeptical of the design, saying that it would be better to just start with a simple construction that would support the plate from the base of the chamber, but I still feel that I would spend too much time adjusting it and moving the plate after each test if I needed to open the chamber each time.

There are a few problems with positioning the rod, since the top openings that I'd wanted to use are too close to parts of the chamber to attach Wilson seals to them (I'll add a picture tomorrow). My plan now is to put it in level with the bottom electrode, since the cloud should always be below that level anyway. We ordered all of the materials, which should come tomorrow or the day after, and then we'll have to get them machined. Grooves will need to be cut into the rod for the fishing line to spool into, the disc will need to be cut out of the sheet of metal we bought, and holes will need to be drilled into the sheet for the line and nozzle. We should be able to put it into the chamber by the end of the week, though hopefully sooner.

In other news, my primary computer (at the lab) died today. First all of it's USB devices (mouse and keyboard) stopped working, and when we tried to reboot it, it gave us a blue screen of death. We've been unable to start it since; it doesn't even respond to the power button. My secondary computer is still functional (though it's not very comfortable to work at), and all of my videos and images were backed up on Dropbox, but most of my recent MATLAB code is only on that computer. We should (hopefully) be able to recover it even if the computer is dead, but it's good that I'm not going to be analyzing any data for a while until we get the new setup running.