Radial current-density distributions and sample charge uniformity in a corona triode

Abstract

Reports on the radial distribution of the current density produced by a corona triode using the metallic point placed in the axis of insulating tubing. The experimental results are fitted with a model, accounting for the space charge in the grid-to-plate gap, and the corona wind. For a small grid bias, the simulation yields a current-density distribution similar to that of the corona-wind velocity. Using a proper feedback control of the grid bias, the charging current can be kept constant, and the resulting charge distribution is almost uniform. The evolutions of the surface charge patterns obtained with and without feedback control of the grid bias are compared.

Chromofore Poling in Thin Films of Organic Glasses. 1. Overview of Corona Discharge Application

“…The constant-current triode corona charger for polymer films [29] does not contain any vibrating elements. In this case the corona triode method is used to control − by voltage-biased grid − the surface potential and ion flow to the sample [30]. When the grid voltage is controlled by means of a feedback current control circuit the charging current is maintained constant.…”

“…Temperature variations at poling affect the corona onset voltage, ion mobility, and, as a result, the V gap responsible for inaccuracies of the value of sample surface potential measured by this method. Versions of constant current corona triode poling setups [29][30][31][32][33][34][35][36][37] have been used in studies of polymer orientation, and their possible usage for poling NLO and HGP samples is still being examined [38,39]. As far as we know, the first system for measuring potential difference across a thin insulating film during the corona discharge has been reported by Weinberg [40].…”

Isothermal charge decay of Teflon-FEP electrets under a corona discharge

“…C -Surface Pote ntial and Centro' Id Measure ments The mean surface potential of the sample was measured by mechanically vibrating the sample and using the Kelvin's method [9]. A scanning capacitive probe was also used to draw the surface potential profile of the sample [lo].…”

Electric measurements with constant current: A practical method for characterizing dielectric films

“…In the 1980's, a corona triode was built which allowed dielectric samples to be charged with a CC, under an open circuit. [6][7][8] In addition to charging control, this corona triode permitted the investigation of electrical properties of polymers 9,10 and even to obtain hysteresis curves for ferroelectric polymers. 11 In this work, the CC method is applied in measurements under the closed circuit condition, i.e., with electroded samples.…”