Experiments on Contact Charging for an Electrostatic Microparticle Thruster IEPC-2009-010 Presented at the 31st International Electric Propulsion Conference, University of Michigan • Ann Arbor, Michigan • USA September 20 - 24, 2009 Thomas Trottenberg ∗ , Viktor Schneider † and Holger Kersten ‡ IEAP, Christian-Albrechts-Universit¨ at zu Kiel, D-24118 Kiel, Germany Abstract: This paper reports on first experiments aiming at an efficient technique for contact charging of microparticles, which could be applied for space propulsion. Fine electrode structures create high electric field strengths at the particle surface when a con- ductive microparticle comes in contact with the high voltage electrode. Besides propulsion of space vehicles, terrestrial applications for surface treatment and as a new particle source for hypervelocity experiments like simulation of micrometeorites appear possible. Nomenclature C = capacitance d 1 ,d 2 = width and separation of conductive lines D i = surface charge density at the particle surface element i E i = electric field strength at the particle surface element i E p = electric field strength at the particle surface e = elementary charge ǫ 0 = permittivity of free space F = electrical field force acting on a charged microparticle P acc = acceleration power φ p = surface potential of a particle m p = particle mass ˙ N p = particle ejection rate q p = particle charge r n = radius of curvature of a needle tip r p = particle radius R = resistance ρ = mass density of a microparticle T = thrust U HV = high voltage potential ΔU = amplitude of the particle detector signal v p0 = velocity of a particle after acceleration ∗ Research Associate, Plasma Technology, trottenberg@physik.uni-kiel.de † Research Associate, Plasma Technology, schneider@physik.uni-kiel.de ‡ Professor, Plasma Technology, kersten@physik.uni-kiel.de 1 The 31st International Electric Propulsion Conference, University of Michigan, USA September 20 - 24, 2009