Weak Double Layers in a Current Carrying Plasma

The existence of weak electric double layers in a current carrying low density plasma is investigated theoretically for an electron distribution function that is of interest in triple plasma devices and Q-machines in double ended operation. In these devices the electron distribution function in the central plasma may be discontinuous since it is made up of contributions from two independent plasma sources. A time evolution equation for a weak double layer is derived for the case of cold ions and a discontinuous electron distribution function. The existence of stationary solutions describing a propagating double layer is demonstrated, and the amplitude of the double layer is found to be proportional to the jump in the electron distribution function at the point of discontinuity. Other properties of this new type of double layer are also discussed.