Current-Voltage Characteristic and Potential Oscillations of a Double Layer in a Triple Plasma Device

摘要

The properties of a strong double layer in a current circuit with a capacitance and an inductance were investigated in a triple plasma device. The double layer produces a region of negative differential resistance in the current-voltage characteristic of the device, and this gives nonlinear oscillations in the current and the potential drop over the double layer (DL). For a sufficiently large circuit inductance DL reaches an amplitude given by the induced voltage which is much larger than the circuit EMF due to the rapid current decrease when DL increases. A variable potential minimum exists in the plasma on the low potential side of the double layer, and the depth of the minimum increases when DL increases. An increasing fraction of the electrons incident at the double layer are then reflected. This is the main process giving rise to the negative differential resistance. A qualitative model for the variation of the minimum potential with DL is proposed.