What are the characteristics you would look for to identify plasma substance

Plasma has similar physical characteristics to gas, in that it flows freely and drifts and separates to fill the container it's in. Plasma occurs at super high temperatures, this strips apart the molecules. It can also occur at relatively cool temperatures, this plasma has very charged particles. They are electrically neutral, as they often contain equal numbers of protons and neutrons. But they are still affected by electric and magnetic fields, because they are so free flowing.

plasma - state of matter made up of electrically charged particles