An induction plasma torch comprises a tubular torch body, a tubular insert, a plasma confinement tube and an annular channel. The tubular torch body has upstream and downstream sections defining respective inner surfaces. The tubular insert is mounted to the inner surface of the downstream section of the tubular torch body. The plasma confinement tube is disposed in the tubular torch body, coaxial therewith. The plasma confinement tube has a tubular wall having a thickness tapering off in an axial direction of plasma flow. The annular channel is defined between, on one hand, the inner surface of the upstream section of the tubular torch body and an inner surface of the insert and, on the other hand, an outer surface of the tubular wall of the plasma confinement tube. The cooling channel carries a fluid for cooling the plasma confinement tube.