Development of electrostatic accelerator for ice dust and the aggregates

点击翻译按钮获取中文摘要

We have developed an electrostatic accelerator to launch a ice dust and ice aggregates at a wide range of velocities from cm/s to km/s. The ice sample launched was prepared by a condensation, method : a cold copper plate cooled by liquid nitrogen was subjected to an air saturated with water vapor at -10℃. The condensed icy dust is an almost spherical shape with the size of 10 μm, Ice aggregates were grown by collecting each ice dust under high electric field more than 100 V/cm. The aggregate was charged under the electric field, so that it was launched by the electrostatic attraction. The relationship between the electric field and the velocity is derived as follows for the aggregates of 500μm.: V_i=0.25(V_<o>/d)^<0.9> (m/s), V_i: velocity, V_o: Voltage, d: distance between electrodes (d=2.5mm). The launch velocity is strongly affected by the air drag for the small aggregates, so we have set a vacuum chamber to eliminate the gas drag to the aggregates in the acceleration. We also used a longer acceleration tube to avoid disruption of the aggregates by the strong attraction force. As a result we have achieved 20m/s for 500μm aggregate at the electric field of 1kV/mm and 1 bar. In the evacuated condition of 0.1 bar, the launched velocity increased about 3 to 4 times higher than that of 1 bar at the same electric field strength. This means that it could be possible to achieve more than 100 m/s for ice aggregate of 500 μm at 1kV/mm.