Effect of diverging variable-cross-section channel on performance of a cusped field thruster

The adaptability of cusped field thruster changes with different operating conditions, especially with different efficiencies, which changes a lot at different gas flow rates. To overcome this problem, a diverging variable-cross-section channel was proposed to improve the performance of cusped field thrusters at low and middle gas flow rate. Meanwhile, two constant-section channels with a big diameter and a small diameter respectively were introduced to be compared with the diverging channel. Although the diverging channel may cause a little decline in the atom density compared to the small constant-section channel, the diverging channel improves the efficiency at both low and middle gas flow rates on the premise of providing a considerable thrust, because it decreases the energy loss of ions at exit and promotes ionization by improving the magnetic mirror ratio. In comparison, both the big constant-section channel and the small constant-section channel have low performances due to a lower density of gas and a bigger wall loss. Therefore, a diverging channel is beneficial to improving the performance of a cusped field thruster at low and middle gas flow rate.