Very nice acoustic waves

With the nice vacuum I got, I was able to form some really large and stable clouds, and was able to pretty quickly produce some consistent dust acoustic waves! Here are some pictures and video of the inside of the chamber:

This is what the inside of the chamber looks like, illuminated by the green laser. The primary electric field is generated by the two ring electrodes, while the dust (silica) sits on the grounded plate below. The plasma charges the dust on the plate, and it is lifted up by the electric field to form the cone-shaped cloud. You can see a small dust acoustic wave in this picture by the light and dark bands of high and low density within the cloud. You can also see the faint purple plasma near upper electrode and in a few spots on the lower one.

By bringing up the pressure and increasing the voltage, we can clearly see the plasma around the top electrode and the grounded plate. The purple spots on the lower electrode are places where the plasma is burning off something.

A spontaneous, stable, dust acoustic wave in the dust cloud. This video was shot by the Phantom camera at 100 fps.

This short video shows a few seconds of the plasma arcing to the sides of the chamber. By significantly raising the voltage, we can get the plasma to arc like this; arcing burns off contaminants in the chamber and gives us a more stable plasma when we decrease the voltage again. Doing this also charges up many dust particles and pulls them up into the field; the longer we arc the plasma, the larger the dust cloud that settles when we bring down the voltage.