Electrosprayed Heavy Ion and Nanodrop Beams for Surface Engineering and Electrical Propulsion

The goal of this project is to study the production and energetic impact of electrosprayed nanodroplets and molecular ions, covering continuously the projectile size range from 1 nm up to hundreds of nm. The 1-20 nm size range is of great interest to achieve variable specific impulse (Isp) from 100 s to approximately 1000 s in drop-based electrical propulsion, while pure molecular ion emission enables higher Isp. Electrosprayed nanodroplets are extraordinary sputtering projectiles (their sputtering rates exceed those of the state of the art ion beam technology by a factor between 100 and 600). Their impact on crystalline substrates produces new and unique phenomena such as surface amorphization and texturing of surfaces with controllable roughness. Electrosprayed molecular ions, many of which contain reactive species and display substantial etching, are equally useful for modifying surfaces. In addition, electrospray sources are ideal for focused beam applications. These findings lead to new opportunities in the fields of electric propulsion (achievement of improved and variable Isp, thrust and power density and propulsive efficiency, quantification of the lifetime of electrospray thrusters), MEMS and IC fabrication (broad-beam and focused-beam nanodroplet and ion sources for high speed beam milling and microrofabrication, reactive nanodroplet and ion etching, polishing of large and curved mirrors), surface processing (patterning of crystalline surfaces with amorphous layers, patterning of a textured surface with controllable roughness, strengthening of materials for increased thruster life, microscopy), and secondary ion mass spectrometry (SIMS) of organic surfaces. The goals of this project are to gain a detailed, first-principles understanding of the production of nanoprojectiles, their interaction with surfaces, and the investigation of the surface processing and propulsive applications outlined above.

This project is a collaboration between research groups of UCI, MIT and Yale University. The key investigators are Prof. Gamero (project lead, nanodroplet beams, UCI), Prof. Fernández de la Mora (electrospray atomization, Yale University), Prof. Paulo Lozano (molecular ion beams, MIT), Prof. Markus J. Buehler (molecular dynamics and multiscale modeling, MIT), Prof. Alessandro Gomez (colloid thrusters, Yale University), Prof Daniel Mumm (materials science, UCI), and Dr. Jian-Guo Zheng (surface spectrometry, UCI).

1. Project Overview
2. Recent Accomplishments
3. Transitions
4. Presentations
5. Reports
6. Publications
7. Miscellaneous