Charge deposition, redistribution, and decay properties of insulating surfaces obtained from guiding of low-energy ions through capillaries

Abstract

We present a combined experimental and theoretical study of the transmission of single charged 1-keV Ar ions through a cylindrical glass capillary of macroscopic dimensions. From quantitative measurements of the incoming and transmitted ion currents, combined with a detailed analysis, the amount of beam entering the capillary was determined. This, combined with the measured transmitted currents, was used to determine the amount of charge deposited on the inner wall of the capillary which produces the guiding electric field. We show experimental results for fully, and partially, discharged conditions of the time evolution of the guided beam intensity following a wide range of times during which the capillary was allowed to discharge in order to provide information about the insulating surface charging and discharging rates. Combining our recent theoretical model describing the charge patch dynamics with these data, it is shown that the model is consistent with the experimental transmission curve data measured after the capillary was allowed to discharge for times ranging from 5 to 1000 s or longer and for injected currents that differed by a factor of 50. In contrast, models which do not include a dynamic rearrangement of charge along the surface prior to decay were found to be inconsistent with our experimental measurements. Additional data about the time dependences of the fraction of the injected beam which is transmitted as a function of injected beam current when transmission through the capillary is inhibited due to blocking are also presented. These data have a temporal dependence consistent with our model predictions that blocking occurs when the total capillary charge, i.e., the capillary potential, reaches a certain value.

Stabilizing the ion-beam transmission through tapered glass capillaries

“…Details about the theoretical model, on which the numerical code is based, can be found in Refs. [2,16,17].…”

Low-Energy Ion Transport Between Two Insulating Parallel Plates

“…To provide additional information for testing theoretical models and simulations of the guiding process we previously reported quantitative data where low-energy argon ions were injected into and transported though a macroscopic glass capillary [18]. For the geometry used, namely where the entrance surface and the outer cylinder surface were grounded, the charging and discharging data were shown to be compatible with a theoretical model where two discharge paths were identified.…”

“…Recently, however, Stolterfoht placed some of the early data on an absolute scale [5]. Such studies have been performed using both microscopic diameter capillaries in insulating foils like polyethylene-terephthalate (PET) [6,7] or in solids such as silicon dioxide (SiO2) [8] and aluminum oxide (Al2O3) [9,10] and using macroscopic diameter glass capillaries [11][12][13][14][15][16][17][18].…”

“…equations 7a and 5 in ref. 18) show the temporal behavior of the deposited charge (Q) for these two scenarios. Here, s and b are decay times for charge flowing along the surface and through the bulk, leak is the combination of these via leak -1 = ks -1 + b -1 , k is a number associated with the electric field produced by the deposited charge, f is the fraction of the deposited charge that flows along the surface, and Q(0) is any residual charge left over from a previous beam injection.…”

Simulations of Ion-Guiding Through Insulating Nanocapillaries of Varying Diameter: Interpretation of Experimental Results

“…Also, electrons were used as projectiles transmitted through capillaries in Al 2 O 3 [17] and PET [18,19]. Moreover, guiding of charged particles have been studied in single-glass capillaries in a tapered geometry [20][21][22][23][24][25][26], a straight geometry [27][28][29][30][31][32], soft curved material [33,34], and between parallel glass plates [35,36]. Further work is discussed in comprehensive articles reviewing the investigations of capillary guiding [37,38].…”