Abstract: An arc gas heater includes an injector unit having a chamber into which high pressure gas is introduced in a swirl and a constrictor passage leading from the chamber so that the swirling gas flows downstream through the constrictor passage. A rear tubular electrode opens into the chamber with its hollow interior axially aligned with the constrictor passage. The injector unit is separated from a tubular front electrode by interelectrode segments having axially aligned tubular inserts which define a continuation of the constrictor passage beyond the injector unit. Located downstream from the front electrode is a convergent-divergent nozzle. Air flowing subsonically through the constrictor passage assumes a relatively high constant pressure therein, and this high pressure demands a greater difference in electrical potential between the two electrodes to maintain an arc in the passage. This arc elevates the energy of the gas in the constrictor passage to extremely high values.

Abstract: An arc heater having dual toroidal rear electrodes is disclosed. In this configuration, the total arc current can be doubled without increasing the rear electrode erosion that would result with a single rear electrode. Alternatively, the total arc current can remain the same, and be divided over the two rear electrodes, and the rear electrode erosion is significantly reduced. In the first instance the gas enthalpy performance of the heater is significantly enhanced, and in the second instance the heated gas contamination is reduced and the rear electrode life is increased. The basic components of the arc heater are a forward electrode and dual rear electrodes, the forward and dual rear electrodes being separated from each other by cylindircal multi-segment non-axial conducting constrictor modules. Provision is made for gas injection throughout the device.