Ion production cost of a gridded helicon ion thruster

Abstract

Helicon plasma sources are capable of efficiently ionizing propellants and have been considered for application in electric propulsion. However, studies that estimate the ion production cost of the helicon plasma source are limited and rely on estimates of the extracted ion current. The ion production cost of a helicon plasma source is determined using a gridded ion thruster configuration that allows accurate measurement of the ion beam current. These measurements are used in conjunction with previous characterization of the helicon plasma to create a model of the discharge plasma within the gridded thruster. The device is tested across a range of operating conditions: 343-600 W radio frequency power at 13.56 MHz, 50-250 G and 1.5 mg s −1 of argon at a pressure of 1.6 × 10 −5 Torr-Ar. The ion production cost is 132-212 ± 28-46 eV/ion, driven primarily by ion loss to the walls and anode, as well as energy loss in the anode and grid sheaths.

Helicon high-density plasma sources: physics and applications

“…Gridded helicon ion thrusters were investigated, although the electrodeless condition is not satisfied in the acceleration process and an additional neutralizer is necessary. The gridded helicon ion thruster (GHIT) [210], with screen and accelerator grids, was investigated in the case of D = 14 cm by measuring the ion beam current. It was found that the estimated cost of E i was 132-212 eV/ion with P rf < 600 W and B < 250 G (EMs).…”

A Directional Microplasma Thruster Exhibiting a Switchable Intense Plasma Coupling

“…5 (a), the single bundle of seven fibers produced a plasma-only thrust 70% greater than the array of seven single fibers at the same gas flow rate and velocity, as a result of jet-to-jet coupling in the bundle array. The increase in the thrust was achieved with an input electrical power of less than 30 W, whereas comparable electric propulsion systems require above 1 kW [8]- [10]. The single bundle with seven fibers under glow discharge generated maximum plasma-only thrusts of 7.8 mN with He and 11.2 mN with Ar, and the combined gas-plasma totals were 61.9 mN and 70.9 mN with He and Ar respectively.…”

“…Plasma-based thrusters have been extensively researched for this specific role in nanosatellites over conventional thrusters as they have reduced propellant consumption and exhibit higher specific impulse [8]- [22]. They are small enough for use on many cubesats and other similar nanosatellite platforms with typical dimensions less than 20 cm × 20 cm × 30 cm, simply designed and require neither explicit neutralizers nor biased electrodes [10]- [22]. However, these systems exhibit relatively low thrust output (< 0.3 mN), and even Hall thrusters of this size generate less than 7 mN thrust (7).…”

Initial Performance Evaluation of a Gridded Radio Frequency Ion Thruster

“…In this particular instance, the comparison is between the cathode or RF discharges in state-of-the-art ion engines and the RF discharge in the GHIT. The benefit of using a nominal helicon discharge to generate ions is that it has the capability for a lower ion production cost than in state-of-theart ion engine discharges, which increases efficiency [45]. One of the key improvements is the axial magnetic field, which provides radial confinement of the ions and reduces wall losses.…”