Temperature Effects on Electrospray Performance
Abstract
Electrospray thrusters have been considered for the past 50 years. However, the low conductivity and high volatility of liquids that were available in the past resulted in thrusters that required too much power for them to be a viable propulsion option. The lack of micro-fabrication techniques also resulted in electrospray thrusters with a large inert mass fraction. These constraints have changed in recent times with the formulation and development of new, higher conductivity ionic liquids. Also, manufacturing processes have improved for micromechanical systems and they now allow wafers to be etched with features compact enough to generate reasonable thrust density. These developments have opened the possibility of having electrospray thrusters moving spacecraft. Electrosprays lend themselves to electric propulsion in two primary ways: easily throttled thrust /specific impulse, and high efficiency without charge accumulation. Ionic liquids have several properties that make them ideal for electrospray. These properties are electrical conductivity, surface tension coefficient, density, and dielectric constant. All of these are affected by temperature changes in various magnitudes and need to be studied to determine the effects this can have on a propulsion system. In this paper, a model of an ionic liquid's properties vs. temperature is presented and predictions of the effects temperature will have on the performance of an electrospray thruster are calculated. Using literature on relevant ionic liquids, a file will be read into a MATLAB(Registered Trademark) script and a prediction will be generated to validate data collected in a laboratory experiment. This script can then be refined and used to design and optimize a thruster for space operation in which the propellant temperature is balanced by mission and energy requirements.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2011
- Accession Number
- ADA549435
Entities
People
- Nicholas A. Kreitinger
Organizations
- Air Force Research Laboratory