Search

In this paper, the relationship between the morphology of the cathode crater and plasma ionization between thrusters is studied by adjusting the input energy of the micro-cathode arc thruster (μ CAT). We monitor the morphology of the cathode crater of the μ CAT using scanning electron microscopy and explore the relationship between the crater morphology and the internal energy loss of the cathode crater. This relationship, combined with the numerical simulation results, is used to monitor the ionization between the electrodes of the μ CAT using an enhanced intensified charge coupled device spectrum detector. The effect of cathode crater morphology on the ionization of the propellant during the operation of the μ CAT is determined. The results show that with a change in the input power processing unit voltage, the external profile and depth-to-diameter ratio of the cathode crater change, resulting in a change in the internal energy loss of the thruster cathode crater and then affecting the ionization efficiency of the cathode working fluid in the μ CAT. Under the condition of basically unchanged cathode feed energy flow density, reasonable adjustment of the depth-to-diameter ratio of the cathode crater can effectively improve the ionization efficiency of the cathode working fluid in the μ CAT. [ABSTRACT FROM AUTHOR]

A magnetically shielded Hall thruster (MSHT) has a significantly longer service life than a conventional unshielded Hall thruster (USHT) as it shifts the magnetic field of maximum strength from the channel interior to the exterior. In this study, it was experimentally determined that the influence of the radial position of an externally mounted hollow cathode on the performance of an MSHT is quite different from that of a USHT. The measured plasma parameters demonstrate that in addition to the coupling voltage loss and plume divergence loss, the electron cross-field transport loss (not considered previously and introduced by the outward shifting of the magnetic field) is also important to explaining the performance variation in the MSHT. This study refines the coupling theory between the cathode and Hall thruster and provides a valuable reference for determining the radial position of an externally mounted hollow cathode in an MSHT. [ABSTRACT FROM AUTHOR]

This study proposes a newly designed ignition circuit that does not change the ignition starting parameters of a Hall thruster, reduces the critical ignition voltage, and improves ignition reliability. The complexity and weight of the Hall thruster power supply system are reduced by multiplexing the ignition and discharge power supplies. Under the condition that the design parameters are satisfied, that is, R 3 + R E C 2 is much larger than RCC1, the residual energy in the circuit after the cathode breakdown can be fed into the thruster discharge channel to improve the ignition energy supply. The experimental results show that when the anode voltage is 98 V, only nine of the 100 ignition tests are successful using the traditional ignition circuit, whereas the number of successes using the newly designed ignition circuit is as high as 99, which provides a simple solution method for improving the ignition reliability. [ABSTRACT FROM AUTHOR]

In this paper, a new “convex” external magnetic pole structure is proposed. With this structure, two different configurations of the cathode inside and outside the magnetic separatrix can be realized by changing the position of the magnetic separatrix instead of changing the position of the cathode in the radial direction. Furthermore, the discharge plume, coupling voltage, and performance of the thruster under different configuration conditions are studied experimentally. The experimental results indicate that, when the cathode is located inside the magnetic separatrix, the effective acceleration voltage is higher, the coupling voltage between the cathode and the thruster is lower, and the thruster performance (including thrust, specific impulse, and efficiency) is higher. When the cathode is located outside the magnetic separatrix, the effective acceleration voltage is lower, the coupling voltage between the cathode and the thruster is higher, and the thruster performance is degraded. When the cathode is located inside the magnetic separatrix, the thrust and specific impulse can be increased up to 2.3%, and the efficiency—up to 4.6%. This study provides a new method for the design of the magnetic separatrix and is of great importance for the coupling-matching design of the cathode and thruster. [ABSTRACT FROM AUTHOR]

A time-resolved optical measurement method is applied to examine the gas discharge process inside the discharge channel during a Hall thruster ignition. The results show that the excitation and ionization processes in the working gas begin near the exit of the channel and then propagate upstream along the channel. The change in energy of electrons moving toward the anode leads to the alternating dominance of ionization and excitation processes, which is the main reason for the changes in light intensity in different regions of the channel during the thruster startup. [ABSTRACT FROM AUTHOR]

Abstract The reliability of cathode is critical to electric propulsion systems. Although researchers have carried out many life tests on hollow cathode, the discharge current is almost steady when the cathode is independently tested for life. Actually, when it is coupled with the thruster, the discharge current is with large amplitude low-frequency oscillation. Therefore, we suggest a new external circuit for a cathode-independent life test, which could simulate the characteristics of discharge current oscillation when the cathode is coupled with Hall thruster. We carried out 160 h of life test using the normal external circuit and the new external circuit, and the variation characteristics of the cathode orifice area are also studied during the life test. The results show that under the normal external circuit, the growth rate of the cathode orifice area initially increases and then decreases gradually with the increase of the time of life test, whilst the cathode orifice area in the new external circuit linearly increases. The new external circuit can provide a new method to simulate the discharge current oscillation when the cathode is coupled with Hall thruster during the independent life test of the cathode. [ABSTRACT FROM AUTHOR]

In this study, the material loss relationship between the electrodes of a micro-cathodic arc thruster was investigated by adjusting the input voltage. The crater morphology of the micro-cathodic arc thruster was observed with a scanning electron microscope. The internal crater material was analyzed with an energy spectrum analyzer. On this basis, the arc path is obtained and the material loss of the structure between the electrodes of the micro-cathodic arc thruster was studied through further numerical simulation. The experimental and simulation results show that with a change in the Power processing unit (PPU) input voltage of the micro-cathodic arc thruster, the material distribution in the cathode crater and the discharge channel between the electrodes changed, affecting the bombardment of ions between the electrodes of the thruster on the insulating structure and conductive coating. In engineering applications, regulation of the arc breakdown path can effectively reduce the total energy of ion bombardment on the wall. • Study on micro-morphology and composition distribution characteristics of arc crater of micro-cathode arc thruster. • Study on the distribution characteristics of PPU input voltage and discharge channel between thrusters. • The ion bombardment on the wall under different discharge channels is simulated. • With the increase of PPU input voltage, the dominant factor of inter-electrode structure loss changes. [ABSTRACT FROM AUTHOR]