The present disclosure relates to a plasma reactor for plasma-based gas conversion comprising a pin electrode extending along a longitudinal axis from a first end to a second end, an opposing electrode opposing a discharge tip of the 10 pin electrode, a plasma chamber for confining a glow discharge plasma, and an electrically-insulating body that comprises an inner bore extending along the longitudinal axis from a bore entrance to a bore exit. The second end of the pin electrode comprises a discharge tip. The pin electrode penetrates the inner bore from the bore entrance and extends at least partly through the inner bore and a15 radial wall of a portion of the inner bore located between the second end of the pin electrode and the opposing electrode, is radially delimiting the plasma chamber. The plasma reactor is further configured for varying an electrode separation distance between the discharge tip of the pin electrode and the opposing electrode.

A heater for heating a gas or gas mixture by electric arc includes a containment structure that defines a heating chamber with gas input and output openings. One or more electrodes are disposed through corresponding holes in the containment structure, with sealing features disposed between respective holes and electrodes. At least one electrically conductive element is disposed at least partially within the heating chamber. An electric arc is supported between the electrode(s) and the electrically conductive element(s).