Electrothermics

2.3. Modeling a plasma installation

Modeling a plasma installation (as described in this chapter) is done in two phases: a simulation of the torch (which requires solving coupled electromagnetic, thermal, and flow problems) and a generator model (which requires solving the circuit’s equations). The coupling algorithm in Figure 2.11 is then used to link the two previous simulations. The generator is supplied at constant voltage U and delivers a voltage V_i at frequency for a given load. The torch supplied at these values is equivalent (for the operating conditions and plasmagene gas flow rate conditions) to an electric charge R_i, L_i. This new impedance is reintroduced in the model of the generator, which calculates a new frequency and a new voltage V_i. These values are then plugged back in the torch’s simulation and the calculation continues until a stable operating point is reached.

Figure 2.11. Coupling algorithm

The necessity of simulating the thermal plasma and the generator separately arises from the disparity of the environments to simulate.

The generator poses many electrical problems, impedance matching problems, and problems of convergence of the numerical models.

The plasma ...