Performance Characterization of the Low-Power Halo Electric Propulsion System

Performance measurements have been obtained of a novel propulsion concept called the Halo thruster under development within the University of Surrey. The Halo thruster, a type of cusped-field thruster with close similarity to the cylindrical Hall thruster, is motivated by the need for low-power and low-cost electric propulsion for the small satellite sector. Two versions of the device are investigated in this study: a design using permanent magnets at high magnetic-field strength and a design using electromagnets with moderate field strength. While operating at 200 W discharge power, which is of particular interest to power-limited small satellite platforms, the permanent-magnet design achieved a maximum thrust efficiency of 8% at a specific impulse of approximately 900 s using a krypton propellant. By comparison, the electromagnet design achieved a maximum thrust efficiency of 28% at a specific impulse of approximately 1500 s at 200 W using a xenon propellant. For higher levels of power (tested up to 800 W), the performance of the electromagnetic design saturated at approximately 25% thrust efficiency using krypton and 30% using xenon. The thrust efficiency of the permanent-magnet design appeared to increase monotonically up to 600 W reaching a maximum value of 14%

Measurement of plasma parameters within the discharge channel of a Halo thruster

The Halo thruster is a cusped field thruster currently under investigation at the Surrey Space Centre, University of Surrey. The concept concerns the addition of a novel toroidal cusp layer, the “halo”, to a magnetic field topology closely resembling that of the Cylindrical Hall Thruster. Preliminary low resolution maps are presented of plasma potential, electron temperature and plasma density within an electromagnet Halo thruster discharge channel, produced using a 2-axis translating Langmuir probe arrangement. Potential drops are observed in both the annular and cylindrical parts of the discharge channel, and a region of high plasma density is revealed on the central axis in the cylindrical part, suggesting performance may be improved by adopting a purely cylindrical geometry

Plasma Generation

A plasma torch having an open end from which a plasma plume is emitted in use is disclosed. The plasma torch includes a central cathode rod, a grounded conductive tube having an open end and being arranged around the cathode and spaced therefrom to form a first cylindrical cavity open at one end; and a high voltage electrode having a dielectric barrier material at a radially inward-facing surface thereof and being arranged around the grounded conductive tube and spaced apart therefrom to form a second annular cylindrical cavity open at one end. A constant direct current (DC) electrical power plus a high voltage pulsed electrical power is provided to the cathode producing an arc discharge in the first cavity between the cathode and grounded tube to generate a central thermal plasma emitted at an open end of the first cylindrical cavity. A high voltage alternating current electrical power or pulsed electrical power is provided to the high voltage electrode producing a dielectric barrier discharge in the second annular cylindrical cavity to generate a non-thermal plasma emitted from an open end of the second cavity as a halo around the central thermal plasma

Plasma Generation

A plasma torch having an open end from which a plasma plume is emitted in use is disclosed. The plasma torch includes a central cathode rod, a grounded conductive tube having an open end and being arranged around the cathode and spaced therefrom to form a first cylindrical cavity open at one end; and a high voltage electrode having a dielectric barrier material at a radially inward-facing surface thereof and being arranged around the grounded conductive tube and spaced apart therefrom to form a second annular cylindrical cavity open at one end. A constant direct current (DC) electrical power plus a high voltage pulsed electrical power is provided to the cathode producing an arc discharge in the first cavity between the cathode and grounded tube to generate a central thermal plasma emitted at an open end of the first cylindrical cavity. A high voltage alternating current electrical power or pulsed electrical power is provided to the high voltage electrode producing a dielectric barrier discharge in the second annular cylindrical cavity to generate a non-thermal plasma emitted from an open end of the second cavity as a halo around the central thermal plasma

Plasma generation

A plasma torch having an open end from which a plasma plume is emitted in use is disclosed. The plasma torch includes a central cathode rod, a grounded conductive tube having an open end and being arranged around the cathode and spaced therefrom to form a first cylindrical cavity open at one end; and a high voltage electrode having a dielectric barrier material at a radially inward-facing surface thereof and being arranged around the grounded conductive tube and spaced apart therefrom to form a second annular cylindrical cavity open at one end. A constant direct current (DC) electrical power plus a high voltage pulsed electrical power is provided to the cathode producing an arc discharge in the first cavity between the cathode and grounded tube to generate a central thermal plasma emitted at an open end of the first cylindrical cavity. A high voltage alternating current electrical power or pulsed electrical power is provided to the high voltage electrode producing a dielectric barrier discharge in the second annular cylindrical cavity to generate a non-thermal plasma emitted from an open end of the second cavity as a halo around the central thermal plasma

Performance characterization of the low-power halo electric propulsion system

Performance measurements have been obtained of a novel propulsion concept called the Halo thruster under development within the University of Surrey. The Halo thruster, a type of cusped-field thruster with close similarity to the cylindrical Hall thruster, is motivated by the need for low-power and low-cost electric propulsion for the small satellite sector. Two versions of the device are investigated in this study: a design using permanent magnets at high magnetic-field strength and a design using electromagnets with moderate field strength. While operating at 200 W discharge power, which is of particular interest to power-limited small satellite platforms, the permanent-magnet design achieved a maximum thrust efficiency of 8% at a specific impulse of approximately 900 s using a krypton propellant. By comparison, the electromagnet design achieved a maximum thrust efficiency of 28% at a specific impulse of approximately 1500 s at 200 W using a xenon propellant. For higher levels of power (tested up to 800 W), the performance of the electromagnetic design saturated at approximately 25% thrust efficiency using krypton and 30% using xenon. The thrust efficiency of the permanent-magnet design appeared to increase monotonically up to 600 W reaching a maximum value of 14%.Read More: https://arc.aiaa.org/doi/abs/10.2514/1.B3609

Overview of Halo thruster research and development activities

The Halo thruster is a low-power plasma propulsion concept, currently under investigation and development within the Surrey Space Centre at the University of Surrey in collaboration with Surrey Satellite Technology Ltd, Airbus DS and Imperial College London. The device is based on the electrostatic acceleration of propellant ions produced in a DC-powered magnetized plasma discharge characterized by a closed-loop electron drift sustained by the combination of electric and magnetic fields. Current research and development activities include: (i) experimental testing of different laboratory models to optimize the thruster performance in the 100 – 200 W power range; (ii) detailed plasma measurements to determine the underlying plasma physics; (iii) implementation of a plasma model for hollow cathode design; (iv) design and manufacturing of an optimized Halo thruster Engineering Model, including a tailored hollow cathode. This paper presents an overview of the aforementioned activities

Overview of Halo thruster research and development activities

The Halo thruster is a low-power plasma propulsion concept, currently under investigation and development within the Surrey Space Centre at the University of Surrey in collaboration with Surrey Satellite Technology Ltd, Airbus DS and Imperial College London. The device is based on the electrostatic acceleration of propellant ions produced in a DC-powered magnetized plasma discharge characterized by a closed-loop electron drift sustained by the combination of electric and magnetic fields. Current research and development activities include: (i) experimental testing of different laboratory models to optimize the thruster performance in the 100 – 200 W power range; (ii) detailed plasma measurements to determine the underlying plasma physics; (iii) implementation of a plasma model for hollow cathode design; (iv) design and manufacturing of an optimized Halo thruster Engineering Model, including a tailored hollow cathode. This paper presents an overview of the aforementioned activities