An experimental study of the nonlinear propagation of an electromagnetic pulse through the ionosphere

This report is concerned with the experimental investigation of EMP propagation through the D-region of the ionosphere. High and low amplitude EMP signals can propagate into space and pose a potential threat to satellites. The Air Force Weapons Laboratory (AFWL) has developed a theory which predicts that when an EMP propagates through the D-region of the ionosphere, considerable energy can be absorbed from this pulse, thus reducing its potential threat. We have built a plasma machine in which pulse propagation in the ionosphere can be simulated. A TEM waveguide is immersed in a nitrogen plasma. We apply a pulse simulating an EMP to the input and observe the received signal at the output. A probe, which can measure the electron distribution function, allows us to monitor the electron temperature. Thus, energy absorbed from the pulse and electron temperature can be monitored. Other diagnostic systems allow many other quantities to be monitored.