Potential Formation and Thermal Insulation between Different Temperature Plasmas

Abstract

Potential formation and reduction of electron heat flow between different temperature plasmas are studied by particle simulations. It is found that the amplitude and even the polarity of the potential difference is 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 with a negative potential dip 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 with respect to thermal insulation.