Potential formation and thermal insulation between different temperature plasmas

Potential formation and associated electron heat flow between different temperature plasmas are studied by means of a particle simulation. It is found that the amplitude and even the polarity of the potential difference can be controlled by the ion to electron thermal velocity ratio. When the ion thermal speed is smaller than the electron thermal speed, the positive potential jump from the cold region to the hot region is created and a negative potential dip is created on its low potential side (cold side). When the ion thermal speed is greater than the electron thermal speed, however, the polarity of the potential structure is completely reversed. With this result in mind, the influence of the potential difference on the heat flow between different temperature plasmas is examined to demonstrate that potential difference can largely contribute to thermal insulation.