Fig. 1. Radial beam current density profiles of 30 cm dual-mode ion thruster.

Fig. 2. The power and discharge loss of 30 cm dual-mode ion thruster with same aperture diameter grid optical system during 300 h operation: (a) Low thrust-high specific impulse mode; (b) large thrust-high power mode.

Fig. 3. The power and discharge loss of 30 cm dual-mode ion thruster with small aperture diameter grid optical system during 300 h operation: (a) Low thrust-high specific impulse mode; (b) large thrust-high power mode.

Fig. 4. Photography of decelerate grid: (a) and (b) are the same aperture diameter grid optical system after 300 h and 600 h operation respectively; (c) and (d) are the small aperture diameter grid optical system after 300 h and 600 h opera-tion respectively.

Fig. 5. Relative variation of decelerate grid apertures diameter at the different radial position after 300 h and 600 h operation: (a) The same aperture diameter grid optical system; (b) the small aperture diameter grid optical system.