Updating the Electrostatic Model for Dust Impact Detection with Antenna Instruments

Abstract Antenna instruments deployed in space are known to be sensitive to dust impacts, and the detected signals can be used to characterize the dust populations within the solar system. Recently, an electrostatic model describing how transient impact plasmas generate characteristic signals measured by antennas was presented. This first-principles model considers the capacitive coupling between the elements of the spacecraft (SC)–antenna system and calculates the collected and induced charging from the expanding impact plasma. Here, the model is updated to include the angular and velocity distributions of the ions in the impact plasma. The relevant parameters of the impact plasma are obtained from laboratory measurements using a dust accelerator. These parameters are further refined by matching the updated electrostatic model to antenna signals collected in the laboratory using a simple model SC. The angular distribution of ion expansion is best described by a cosine distribution, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msup> <mml:mrow> <mml:mi>cos</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>β</mml:mi> </mml:mrow> </mml:msup> <mml:mi>θ</mml:mi> </mml:math> , with β = 1. The velocity distribution considers heavy-, medium-, and low-mass ions present in the impact plasma with corresponding velocities of 3.8, 14, and 36.7 km s −1 for high speed dust impacts. The updated electrostatic model provides excellent agreement with antenna measurements collected in the laboratory and can be used as a basis for analysis and precise interpretation of dust impact data collected by antenna instruments on various space missions.