Electron-induced vibrational excitation of ${\mathrm{CO}}_2$ in dc electric and magnetic fields

In the present study rate coefficients for vibrational excitation of ${\mathrm{CO}}_2$ gas molecules by electrons in the presence of uniform electric and magnetic fields are investigated. Calculations are performed for transition from the ground state to each of the symmetric, asymmetric, and bending vibrational states. A Monte Carlo simulation is used to produce nonequilibrium electron energy distribution functions. Results are obtained for the electric field over gas number density ratio, E/N, ranging from 20 to 1000 Td, and for the magnetic field over gas number density ratio, B/N, with values of 0, 1000, 2000, and 3000 Hx.

Figure 1

Cross sections for electron collisions with ${\mathrm{CO}}_2$. The inset shows integral cross sections for excitation of symmetric modes in the range of the resonance from earlier measurements by our group [11].

Figure 2

Electron drift velocity vs reduced electric field.

Figure 3

Longitudinal (a) and transverse (b) diffusion coefficient to mobility vs reduced electric field.

Figure 4

Density normalized effective ionization coefficients vs reduced electric field: open circle, present results; solid square, Hernández-Ávila et al. [49]; open square, Lakshminarasimha et al. [52]; solid line, Deng and Xiao [53]; open diamond, Vass et al. [51]; left-facing triangle, Townsend [54]; right-facing triangle, Bhalla and Craggs [55]; and solid diamond, Schlumbohm [56]. The inset shows comparison in the low E/N range: open circle, present results; solid circle, Hernández-Ávila et al. [49]; open triangle, Yousfi et al. [57]; star, Chatterton and Craggs [58]; and solid line, Vass et al. [51].

Figure 5

Electron energy distribution function obtained by simulation at E/N = 120 Td and B/N = 0 Hx, which corresponds to a mean electron energy of 4.1 eV, compared to the Maxwell-Boltzmann distribution.

Figure 6

Partial rate coefficients for symmetric vibrational mode excitation vs reduced electric field for various B/N values.

Figure 7

Total rate coefficients for symmetric vibrational mode excitation vs reduced electric field for different reduced magnetic field values.

Figure 8

Rate coefficients for bending vibrational mode excitation vs reduced electric field for different reduced magnetic field values.

Figure 9

Rate coefficients for the (120) vibrational mode excitation vs reduced electric field for different reduced magnetic field values.

Figure 10

Rate coefficients for the (001) vibrational mode excitation vs reduced electric field for different reduced magnetic field values.