Potential double layers in double plasma device

Results of the investigation on the formation of double layers in double plasma device are presented. By appropriate modifications in the biasing conditions, we have been able to obtain both weak (eΔφ<10KT _e ) and strong double layers (eΔφ>10kT _e ) in the device. Unlike previous experiments, we have not been limited to potential jumps equal to ionisation potential of the neutral gas. A detailed investigation has been carried out to find out why earlier experiments in similar devices were limited to only weak double layers. We have also investigated the phenomenon of the so-called psuedo-double layers and have shown that they are potential jumps over the thickness of the order of Debye length and precede plasma expanding with velocity many times the ion-acoustic velocity. They do not represent metastable states of the plasma as suggested by earlier investigators.