Sitael Hollow Cathodes for Low-Power Hall Effect Thrusters

Abstract

Low-power Hall effect thrusters (HETs) belong to a class of electric thrusters with an operating power lower than 500 W. The application of this class of HETs is suited for small satellites for telecommunications and Earth observation missions. Sitael is active in this field, through the development of two HETs, HT100, and HT400, belonging to a power class of 100 and 400 W, respectively. HT100 is a permanent-magnet thruster operating in the 100- to 250-W range, providing thrust between 4 and 13 mN, and specific impulse between 900 and 1400 s. HT400 operates in the 350- to 750-W range, providing thrust between 20 and 45 mN, and specific impulse between 1300 and 1700 s. Two cathodes have been developed and tested, referred to as HC1 and HC3, conceived for HT100 and HT400, respectively. Both cathodes are based on Sitael heritage in theoretical modeling and experimental activities for the development of such devices, and rely on lanthanum hexaboride emitters. HC1 is a cathode designed to provide a discharge current in the 0.3-1 A range, operating in steady-state conditions at mass flow rates between 0.08 and 0.5 mg/s of xenon. HC3 was designed for the range 1-3 A of discharge current, with 0.08-0.5 mg/s of mass flow rate. Both HC1 and HC3 have an expected lifetime higher than 10⁴ h, based on the rate of material evaporation from the emitter surface, computed with the aid of a theoretical model developed to guide the cathode design. Experiments were carried out, including preliminary characterization campaigns, of each of the two cathodes and HET-cathode coupling tests. The collected data are presented and discussed with reference to the model predictions, showing a good agreement between theoretical and experimental results

Research on the neutralization control of the RF ion micropropulsion system for the ‘Taiji-1’ satellite mission

“…Plasma cathodes also reduce the specific impulse of the propulsion system due to use of propellant to sustain plasma. Hollow cathodes have demonstrated a discharge current in the range of 0.3-1 A; these cathodes operate in steady-state conditions at mass flow rates between 0.08 and 0.5 mg s −1 of xenon [11]. These cathodes require additional power to heat the thermionic emitter.…”

Impact of exterior electron emission on the self-sustaining margin of hollow cathode discharge

“…Currently, the main approach of lowering the self-sustaining margin is to reduce thermal expense [10]. Adopting materials with lower work function, such as BaO, can reduce the working temperature from 1600 °C in LaB 6 cases to 1000 °C [11][12][13]. Meanwhile, more delicate optimization of thermal design can reduce the thermal loss [11,14].…”

3D‐Printed Multilayered Reinforced Material System for Gas Supply in CubeSats and Small Satellites

“…[19][20][21][22][23] However, novel materials are urgently needed to build the most advanced, miniaturized spacecraft. Electric propulsion is very attractive and could replace cold gas propulsion and chemical propulsion due to favorable parameters, such as high specific impulse, availability of miniaturized versions, and a wide range of applications.…”

“…While ion thrusters have their own advantages and disadvantages, miniaturized Hall thrusters are considered a more reliable technology for CubeSat propulsion because of their less complex design, high thrust to weight ratio, and lower power consumption. [19][20][21][22][23] However, novel materials are urgently needed to build the most advanced, miniaturized spacecraft. [7,11,[24][25][26] In this article, we describe a 3D-printed, reinforced multilayered material to be used for a gas supply system (high-pressure gas tank) for a CubeSat of 1U only, i.e., with standard dimensions 10 Â 10 Â 11 cm (Figure 1a,b).…”

“…Ion thrusters and Hall effect thrusters are the most studied, experimented, and commonly used electric propulsion thrusters. While ion thrusters have their own advantages and disadvantages, miniaturized Hall thrusters are considered a more reliable technology for CubeSat propulsion because of their less complex design, high thrust to weight ratio, and lower power consumption …”