Characteristics of a dust trajectory sensor.

Trajectories of cosmic dust particles are determined by the measurement of the electrical signals that are induced when a charged grain flies through a position-sensitive electrode system. A typical dust trajectory sensor has four sensor planes consisting of about 16 wire electrodes each. Two adjacent planes have orthogonal wire directions. The sensor is highly transparent and mechanically robust, provides a large sensitive area, large field of view, and can, at least in principle, achieve unlimited precision. While a sensor model had already undergone limited testing in the dust laboratory, its response as a function of position and angle of incidence of the trajectory and as a function of sensor dimensions was generally unknown. To better understand its characteristics, the operation of a sensor model consisting of three planes and seven wires per plane was simulated using the COULOMB computer program. We show that the response of the reduced model can be applied to a model with more planes and more wires per plane. The effect of a trajectory's position and angle on the signal strength is discussed as well as the influence of geometrical parameters such as wire diameter, distance between wire planes, and wire length. We found a greater effect of the wire diameter on the signal strength, and a lesser effect of the plane distance, than expected. A set of similarity rules is provided for the design of a larger sensor. Finally, we discuss the optimization of the sensor for different applications.