(a) Schematic of an RF induction thermal plasma system developed for the largescale synthesis of high quality small-diameter BNNTs using the atmospheric pressure HABS process. Pure h-BN powder is continuously transformed into BNNTs by passing through a high temperature N2-H2 plasma (~8000 K). (b) Calculated temperature distribution inside the reactor. The right-hand side shows the hot temperature zone above 4000 K. (c) Calculated velocity distribution (left) and streamlines (right). Net plasma power: 35 kW; pressure: 93 kPa; central gas: Ar (30 slpm); sheath gas: a ternary mixture of Ar (45 slpm), N2 (55 slpm),