Ionic liquid electrospray beam target performance characterization.

Area of Science:

• Spacecraft propulsion
• Plasma physics
• Materials science

Background:

• Electrospray thrusters are vital for long-duration space missions, but ground testing is complicated by facility effects.
• Previous research focused on beam physics and plume dynamics, neglecting facility interactions.
• Facility effects, such as secondary particle generation, can significantly impact thruster performance and lifetime.

Purpose of the Study:

• To characterize the significance of secondary particles generated by ionic liquid electrospray impacts on a beam target.
• To investigate the influence of a novel beam target design and biasing on these secondary particles.
• To provide experimental and modeling data for mitigating facility effects in electrospray thruster testing.

Main Methods:

• Experimental measurements of secondary current and mass flux from a beam target.
• Initial time-of-flight measurements of secondary particles.
• Computational modeling to support experimental data interpretation.

Main Results:

• Identified secondary particles with charge-to-mass ratios as low as 31 C/kg.
• Demonstrated that improper beam target biasing or absence of a target can inflate emitted current by up to 20% due to electron backstreaming.
• Optimized beam target and screen voltage identified as -100 V and -200 V, respectively.

Conclusions:

• Facility effects, particularly secondary particle generation and electron backstreaming, must be considered for accurate electrospray thruster testing.
• Proper beam target design and biasing are essential to mitigate these effects and prevent artificial inflation of performance metrics.
• This research enhances the understanding and mitigation of facility effects, crucial for qualifying electrospray thrusters for spaceflight missions.