Top panel: C⁺ relative abundance as a function of the distance from the vortex axis during the active stage of the TDR model. Bottom panel: cooling rate associated with the transition of C⁺ as a function of time during the relaxation stage of the TDR model. The model is computed for n_H = 100 cm^-3, a = 10^-11 s^-1, and several values of the visible extinction A_V: 0.1 (red), 0.2 (magenta), 0.4 (cyan), and 1.0 (blue) mag.