arXiv subjects
Publications and source records attributed to O. Marghitu.
We present Cluster measurements of large electric fields correlated with intense downward field-aligned currents, and show that the data can be reproduced by a simple model of ionospheric plasma depletion caused by the currents. This type of magnetosphere-ionosphere interaction may be important when considering the mapping between these two regions of space.
Results from the Modified Three Gradient Method (MTGM), applied to a pulsed high intensity electron source, are presented. The MTGM makes possible the non-destructive determination of beam emittance in the space charge presence [1]. We apply the MTGM to an experimental system equipped with a Pierce convergent diode, working in pulse mode, and having a directly heated cathode as electron source. This choice was mainly motivated by the availability of an analytical characterization of this source type [2], as well as the extended use of the Pierce type sources in linear accelerators. The experimental data are processed with a numerical matching program, based on the K-V equation for an axially symmetric configuration [3], to determine the emittance and object cross-over position and diameter. The variation of these parameters is further investigated with respect to both electrical and constructive characteristics of the source: cathode heating current, extraction voltage, and cathode-anode distance.