Plasma deflagration and the properties of a coaxial plasma deflagration gun

The concept of plasma deflagration is investigated theoretically and experimentally. Deflagration is a heating process which adds energy to a flowing stream under expansion. The equations governing the process are the same as the detonation "snowplough" process; therefore, deflagration is nothing more than the second solution of the set of conservation equations.The deflagration process is thoroughly studied in the field of chemical combustion. An analogy between combustion and magnetized plasma is made, and the second law of thermodynamics is invoked in the discussion on the limits of the existence of deflagration solutions. The deflagration process that occurs in a gaseous discharge can accelerate particles to very high velocities at relatively low thermal energy. The deflagration discharge wave always propagates towards the high gas pressure and the high magnetic field region. The wave can be made stationary by injecting neutral gas into the wave. The discharge zone is thick, which reduces the local current density with a given total current and the erosion of electrodes can thus be reduced.A coaxial plasma gun has been designed, based on the deflagration principle, which demonstrates the features predicted by the deflagration hypothesis. The energy of the plasma stream thus produced exceeds 10 keV (> 108 cm/sec with D2).The discharge wave is found to be thick and the wave is quasi-stationary inside the gun barrel. Besides the high velocity capabilities, the gun can focus the plasma to a very small area. This provides a unique opportunity to perform plasma injection experiments with strong magnetic fields (> 100 kG).