I. Introduction
The Quad Confinement Thruster (QCT) is a new concept in electric propulsion (EP) with a key benefit of being able to vector the direction of thrust without the use of moving components. The principle of operation is similar to a Hall effect thruster (HET). A magnetic field is imposed between an anode and an external hollow cathode neutralizer. An electric field is sustained across the magnetic barrier, which acts to accelerate a beam of ions from the device. Thrust vectoring is accomplished by manipulating the topology of the imposed magnetic field barrier, which is formed by a quadrupole arrangement of eight electromagnets spaced around the periphery of the thruster. The magnetic topology for a symmetrically imposed field is shown in Fig. 1. Previous experiments have shown a thrust vectoring capability of approximately 11° off of the thruster axis (22° total angular range) [1]. This level of thrust vector control is comparable with a typical electric thruster gimbal mechanism, such as the SMART-1 gimbal platform that provided a 10° cone, in which the thrust vector could be pointed [2]. By alleviating the need for a gimbal mechanism, the savings in terms of mass and complexity could be significant. The mass of the QCT electromagnets and supporting structure is 2.3 kg, which accounts for roughly 50% of the overall mass of the thruster (4.4 kg).
Magnetic field topology for the Quad Confinement Thruster.