Some of you may know this experiment (Grape + Microwave oven = Plasma video link):
- take a grape that you almost split in two parts, letting just a tiny piece of skin making a link between each half-part.
- put that in a microwave oven, and few seconds later, a light ball which seems to be a plasma appears upon that grape
Looking through google to understand why this phenomenon happens, I have found either laconic or partial answers to that question.
In broad strokes, this what I understand :
Microwaves seem to create an electric current in the grape because of ions.
- Why do grapes contain ions ?
Suddenly the tiny link between the two half-parts is broken which creates an electric arc
- How is that link broken ?
In parallel, the grape is warmed up and a gas is released from the grape
- What is this gas made of? Water? Sugar?
The combination of the electric arc in that gas creates a plasma
- What is the necessary condition for a gas crossed by an electric arc to create plasma?
Is that correct?
Are there any relevant parameters (microwave frequency, grape size, grape orientation) that make it work?
Any idea of the order of magnitude for the intensity involved, the voltage of such an arc, the temperature reached (I've read 3000 degrees!)?
Has someone a complete explanation to provide (reference to physical principle would be appreciated!)?