A combustion mixture of a hydrocarbon and air is injected into the plasma chamber along the direction of the plasma vortex, causing the plasma arc attachment to the anode to be in the diffusion attachment mode, where the plasma arc attaches to the anode surface over a large area, thereby substantially reducing the anode erosion rate. By modulating the plasma arc current with very sharp plasma arc current pulses at a frequency related to the dwell time of the spray particles in the plasma, multiple sequential plasma shock waves which disintegrate the spray particles and accelerate them toward the target substrate. The increased velocity of the spray particles combined with their smaller size results in greatly increased cooling rates when they impact the target substrate, thereby resulting in amorphous spray-coatings as well, with improved characteristics, including decreased porosity, higher tensile bond strength, and increased hardness, as well as having a greatly increased deposition rate. The plasma arc current is precisely controlled to assure small time constant in the plasma so that rapid changes in the plasma arc current are forming the plasma shock waves that strongly impact the spray particles.

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