The 29th International Electric Propulsion Conference, Princeton University, October 31 – November 4, 2005 1 Hall Thruster Scaling Methodology IEPC-2005-187 Presented at the 29 th International Electric Propulsion Conference, Princeton University, October 31 – November 4, 2005 Mariano Andrenucci * Alta S.p.A., 56121 Ospedaletto, Pisa, Italy Francesco Battista^ and Pietro Piliero^ Centrospazio, 56121 Ospedaletto, Pisa, Italy Abstract: This paper is a part of a continuing study on the scaling of Hall effect thrusters, aimed at providing guidelines for the extension of design criteria for this type of thruster to a broader application range. The study has been further developed through a more refined modeling of the physical processes involved. A general description of the methodology is first provided. The theoretical model serving as a basis for the analysis is shortly reviewed. The model is based on a number of scaling relations between the relevant system parameters. These can be translated into a consistent set of scaling modes enabling us to size a thruster of larger or smaller power and/or modified performance with respect to the thruster chosen as a reference. Results of the method are in excellent agreement with the available data on the behavior of real devices. Nomenclature A  scaling vector b channel width B magnetic induction field B  scaling vector d channel average diameter e electron charge E electric field G  scaling vector h ins insulator thickness I D discharge current I j ion current I e electron current i electron loss parameter I sp specific impulse k rI exponent for i-th parameter in scaling relation r K matrix of of k rI , Boltzmann constant L length, channel length L a acceleration length L i ionization length L d diffusion length M i ion mass  m total mass flow rate  m j ion mass flow rate  m * ideal mass flow rate n number density n e electron number density n i ion number density N particle flux P D discharge power P w total wall power loss Q w energy flow to the wall per unit surface R ion ion production rate S channel cross section ____________________________________________________ * Professor, Department of Aerospace Engineering, University of Pisa, Italy. Chairman, Alta S.p.A, Pisa, Italy. Senior Member AIAA. E-mail: m.andrenucci@alta-space.com ^ Graduate student