DC arc plasma torch, for obtaining a chemical substance by decomposition of a plasma-generating gas

A DC arc plasma torch, in particular intended for obtaining a chemical substance from a plasma-generating gas (P) which includes said substance, said torch comprising,

• a first electrode and a second electrode, said electrodes being tubular, coaxial and arranged in extension of each other, on either side of a chamber (3) for injection of said plasma-generating gas, said electrodes being open at their ends which face said injection chamber, and
• means (34) for injecting a stream of the plasma-generating gas into said injection chamber, the arc (10) between said electrodes passing through said injection chamber and being anchored by end feet (10c, 10a) respectively to the internal surface of said electrodes, while said first electrode (2) is open at its end remote from said injection chamber in order to allow the plasma (13) generated by said are to flow out of the torch, wherein:
• said first electrode (2A) is in communication with said injection chamber (3) via a first tubular piece (2B) through which said arc (10) passes and which constitutes a first reaction chamber in which said plasma-generating gas (P) gives rise to the plasma (13) under the action of said electric arc (10);
• and
• first means (7, 8, S) are provided to form a fluid barrier (14) between said first electrode (2A) and said plasma (13), wherein said first means consist of first blowing means (7, 8, S) which generate, on the internal wall of said first electrode (2A), a first tubular flow (14) of a gas at a pressure at least approximately equal to that of the plasma and at a temperature very much lower than that of said plasma (13), said first tubular fluid flow (14) surrounding said flow of the plasma (13) and flowing in the same direction as the latter.