Abstract
A new balloon-borne instrument created by the authors and referred to as the q-d instrument that measures the charge q and size d of precipitation particles is discussed. The instrument measures charge with an induction cylinder size with an optical sensor, and fall speed by the time difference between the two. A second induction cylinder at the top serves as the entry point and detects precipitation that splashes off the entry. In this way, particles contaminated by splashing are removed from the data. It is capable of measuring particle sizes ranging from 0.8 to 8.0 mm in diameter and charges ranging from ±4 to ±400 pC. Since the size is measured optically, one can detect uncharged particles and measure their size. The q-d instrument does not show evidence of corona at its extremities until the electric field is as large as 100 kV m−1 at 700 mb.
