Anomalous viscosity in partially ionized gases

Summary form only given. The plasma window is a novel apparatus that utilizes a stabilized plasma arc as an interface between vacuum and atmosphere or pressurized targets without solid material. Three effects can enable a plasma to provide a rather effective vacuum separation, and hence act as a window. 1) Ideal Gas Pressure Effect, p=nkT that facilitate pressure equalization between a discharge and atmosphere or a high temperature gas channel and atmosphere. Since plasmas have high temperature, their pressure can be matched with a lower density. 2) Dynamic Viscosity Effect: viscosity increases with temperature. Consequently, gas flow through a hot plasma filled channel is greatly reduced. 3) Ionization Effect: atoms and molecules are ionized and trapped in the plasma. Experimentally, the plasma window has performed better than theoretically predicted by these effects, and choked flow conditions occur at pressures lower than expected. Quantitative analysis of the three effects suggested that an anomalous viscosity can explain the discrepancy. Some experimental verification of the anomalous viscosity is presented.