Fast electrostatic diagnostic of an electron beam in a Penning-Malmberg trap

The experimental characterization of free running, small (5-20 cm length, 0.5-1 cm radius) electron bunches in the keV energy range has a great importance for free electron laser (FEL) development. A fast electrostatic diagnostic on a pulsed beam produced with a photocathode source has been developed in the Penning-Malmberg trap ELTRAP, in which electron bunches move along the axis of the trap, from the source towards a charge collector. Low noise electronics has been used in order to measure small induced current signals on the device electrodes for the mentioned diagnostic purposes. Data post processing has been performed using the discrete wavelet transform tool. The development of an effective electrostatic diagnostic, together with proper data analysis techniques, is of general interest for obtaining the beam properties through the comparison of the post-processed data with the theoretically computed signal shape, which contains the beam radius, length and average density as fit parameters. This kind of diagnostic is also of general interest for trapped non-neutral plasmas investigations.