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Contemporary Machining Processes
to a two-cycle scheme, some with counter flows of plasma, still others are combinations of two HFI-discharges burning in one discharge chamber or combined HFI/
HFC plasmatrons supplied with the same two-cycle scheme. Ultrashort-wave (USW)
plasmatrons operate at frequencies from above 50 to 150 MHz. They are characterized by large volumes of plasmas, ca. 1–2 liters, and low densities of energy, less
than 1 W/cm 3 . This is achievable for the atmospheric pressure and low specific power
(Toumanov, 2003).
FIGURE 1.14 Direct current plasmatrons: (a) free-burning arc (transferred arc), and
(b) plasma torch (non-transferred arc). 1 – Nozzle, 2 – Tungsten electrode, 3 – Coolant,
4 – Workpiece, 5 – Injection of plasma-forming gas, 6 – Channel for the introduction of a
processing powder.
FIGURE 1.15 High-frequency plasmatrons: a) High-frequency inductive (HFI) plasmatron; b) High-frequency capacitive (HFC) plasmatron; c) Ultrashort-wave (USW) plasmatron. 1 – Power supply, 2 – Discharge, 3 – Plasma stream, 4 – Coil, 5 – Discharge chamber,
6 – Electrode, 7 – Waveguide.