Development of electrostatic accelerator for ice dust and the aggregates

我们研制了一台发射冰尘和冰团的静电加速器，发射速度从厘米/S到公里/S。发射的冰样是用凝聚法制备的：将液氮冷却的冷铜板置于-10℃饱和水蒸气中。凝聚的冰尘呈近球形，大小约为10μm，在高于100V/cm的高压电场下收集冰尘，形成冰粒聚集体。聚集体在电场下带电，因此它是通过静电吸引而发射的。对于500μm的聚集体，电场与速度的关系式为：V_i=0.25(V_t；o&gt；/d)^&lt；0.9&gt；(m/S)，V_i：速度，V_o：电压，d：电极间距(d=2.5 mm)。小集料的空气阻力对发射速度有很大影响，因此我们设置了真空室来消除加速过程中气体对集料的阻力。我们还使用了较长的加速管，以避免强大的吸引力破坏集合体。结果表明，在1KV/mm、1bar的电场下，500μm的总功率达到了20m/S。在真空为0.1bar的条件下，发射速度比相同电场强度下的1bar提高了约3~4倍。这意味着，在1KV/mm下，对于500μm的冰集料，有可能达到100m/S以上。

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.