Guiding of highly charged ions through insulating nanocapillaries

Abstract: This thesis contains experimental work on guiding of highly charged ions through insulating nanocapillaries. We have studied the time evolution of angular distributions of transmitted ions under well defined initial conditions: already charged, as well as fully discharged nanocapillaries, by using a two-dimensional position sensitive Micro Channel Plate detector with a data acquisition system working in event mode. Time-dependent features in the ion-guiding properties have been found. For the initially discharged capillaries, a shift and broadening of transmitted angular distribution have been observed in the charge-up process. This is interpreted by the formation of charged patches downstream of the entrance patch. We have, with the help of a model calculation, quantitatively derived distinct charge patterns, resulting in the time evolution of the transmitted angular distributions. We show that all charge patches are maintained in the stationary state of transmission by the followed discharging and recharging measurements. For already charged nanocapillaries, a double peak structure in the angular distribution has been found, which is attributed to a memory effect and the re-arrangement of charge patches. When the tilt angle of the capillaries is changed, the existing charge patches from the previous tilt angle can affect the ion trajectories and the formation of new patches.The preliminary results of highly charged ions transmitted through muscovite mica capillaries of rhombic cross section are also presented in this thesis. We have shown the transmission profiles for various orientations of the rhombi. A rectangular shape of the transmission profile has been found. We have performed a simulation by considering the image force from the four sides of the rhombus. To our surprise, this effect gives an angular distribution that agrees well with the transmission profile obtained by the experiment.