Fig. 1. Model sketch of external SGEMP of cylinder

Fig. 2. Distribution of electrons in different fluence of X-ray at 24 ns

Fig. 3. Waveform of emitting current and absorbing current by cylinder in fluence of 0.4 J/cm²

Fig. 4. Distribution of electric field on central line of emitting surface (y=0，x=10.2 cm) in different fluence of X-ray (t=24 ns)

Fig. 5. Distribution of magnetic field on boundary line of emitting surface (x=0, y=10.2 cm) in different fluence of X-ray (t=24 ns)

Fig. 6. Physical model of external SGEMP in background plasma

Fig. 7. Distribution of electric field on central line of emitting surface (y=0, x=10.2 cm) and magnetic field on boundary line of emitting surface (x=0, y=10.2 cm) with fluence of 4×10⁻² J/cm² respectively in different density plasma (1×10⁸ cm⁻³, 5×10⁹ cm⁻³) at 24 ns

Fig. 8. Peak electromagnetic field versus X-ray fluence respectively in vacuum, background plasma of low density (1×10⁸ cm⁻³) or dense density (1×10⁸ cm⁻³)

Fig. 9. Waveform of emitting current and absorbing current by cylinder in plasma density of 5×10⁹ cm⁻³ with fluence of 0.4 J/cm²

Fig. 10. Physical model of external SGEMP in low pressure air

Fig. 11. Distribution of electric field on central line of emitting surface (y=0, x=10.2 cm) and magnetic field on boundary line of emitting surface (x=0, y=10.2 cm) with fluence of 4×10⁻² J/cm² excitated by both photocurrent emitting from surface and secondary electrons at 50 ns

Fig. 12. Energy spectra and angular distribution of photoelectrons produced in air

Fig. 13. Distribution of electric field on central line of emitting surface (y=0, x=10.2 cm) and magnetic field on boundary line of emitting surface (x=0, y=10.2 cm) with fluence of 4×10⁻² J/cm² excitated by photocurrent emitting from both surface and air、secondary electrons together at 50 ns

Fig. 14. Peak electromagnetic field versus X-ray fluence respectively in vacuum, ionization or both ionization and air photoelectrons environment