Fig. 1. Schematic of the DC-RF hybrid plasma torch structure (a) and grid (b)

Fig. 2. Simulation results of the turbulent model (a) and laminar model (b)

Fig. 3. Spatial distribution contours of the temperature under different DC arc currents

Fig. 4. Spatial distributions of the flow field under different DC arc currents

Fig. 5. Distributions of the plasma velocity along the axis direction under different DC arc currents

Fig. 6. Calculated distributions of the temperature and flow field with plasma gas rate Q_R = 30 L·min^-1 (a) and 5 L·min^-1 (b)

Fig. 7. Distributions of axial temperature along the outer torch wall with different Q_R values

Fig. 8. Distributions of the plasma velocity along the axis direction with different Q_R values

Fig. 9. Calculated distributions of the temperature and flow field with cooling gas rate Q_C = 92 L·min^-1(a) and 23 L·min^-1 (b)

Fig. 10. Distributions of the temperature along the outer torch wall in the axis direction with different Q_C values

Fig. 11. Distributions of the plasma velocity along the axis direction with different Q_C values

Fig. 12. Calculated distributions of the temperature and flow field with coil current I_RF = 295 A (a) and 215 A (b)

Fig. 13. Distributions of axial temperature along the outer torch wall with different I_RF values

Fig. 14. Distributions of the plasma velocity along the axis direction with different I_RF values