  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.
