Abstract

The dynamics and transformations of defects in chiral nematic droplets P in the electric field are studied experimentally, as function of the ratio of the droplet radius R to the helix pitch P. It is shown that, depending on the R/P ratio and the applied voltage, various orientation-structural transformations can be realized. In particular, for the ratio R/P<1 only droplets with one destroyed boojum are observed. The application of an a.c. electric voltage causes the latter to rotate. In the case of R/P~1, the dynamics of the rotation of the disclination line is transform into a periodic decay of the boojum (with a topological index S=1) into two surface defects. In the case R/P>1, a process of merging two surface defects with a topological index 1/2 into a bulk defect of the ”hedgehog“ type with S=1 is observed. The mechanisms of the observed processes are discussed.