Research on Beam-Focusing Characteristics of Krypton Hall Thruster

The reserves of krypton are abundant, and it has become an important high specific impulse substitute for Hall thrusters as its physical properties are closest to xenon. However, it has been found that the plasma beam of a Hall thruster has weak plume-focusing characteristics and the half-divergence angle is large when using krypton as a propellant. In this paper, the thrust, specific impulse, efficiency, and plume half-divergence angle of a Hall thruster under different propellant supply flow rates are measured. In addition, the influences of the magnetic field configuration and cathode heating power on the beam-focusing characteristics are researched. The results show that the magnetic field mainly affects the beam-focusing characteristics by the bending direction of the magnetic field lines, thus causing the divergence, focusing, and overfocusing phenomena of the plasma plume. Excessive cathode heating power changes the low-frequency discharge amplitude of the Hall thruster, affects the ionization distribution and the width of the main ionization region, and thereby changes the plume focusing state.