First electron pulses for ALBA

Last week the first electrons were seen out of the electron gun of the ALBA Linac.

This was during the Factory Acceptance Test of the e-gun that took place the 15.11.07 at the premises of EuroMev, a subcontractor of THALES Communications, who’s providing the 100 MeV linac as a turn-key system to ALBA.

The electron gun has been tested both in single bunch and multi bunch mode. The beam went through the first Linac elements up to the Faraday cup placed after the subharmonic prebuncher (see picture above).

The beam pulse has been measured using the Fast Current Transformer placed just after the electron gun and the Faraday cup which was used also as beam stopper.

At this stage only the electron gun has been tested, with the other components switched off.

The response of the e-gun was as specified. The pulse width is 0.8ns for a single pulse which is better than 1ns specified.

The timing board of the electron gun provides a wide range of configurations increasing the flexibility of the SR filing pattern in the future.

In single bunch mode the electron gun can provide up to 16 pulses with a minimum time interval of 6ns. In multi bunch mode the pulse consists of a train modulated at 500MHz. The pulse length is variable and it can range from 4 ns up to 1μs.

Further tests with the subharmonic prebuncher powered will allow a finer setting of the parameters for the optimization of the pulse compression in the bunching section.