2019-12-10
RF Gun for ELI-NP Gamma Beam System, delivered

The RF GUN of the ELI LINAC is a 1.6 cell gun of the BNL/SLAC/UCLA type. Based on an innovative technology, the gun cells are clamped together with no brazing cycles required. A fully clamped structure reduces the RF break-down probability since the copper is kept hard and not annealed.

The ELI GUN has the following improvements:

1) the iris profile has an elliptical shape and a larger aperture to simultaneously reduce the peak surface electric field, to increase the frequency separation between the two RF gun modes (the working π mode and the so called 0-mode) and to increase the pumping speed on the half-cell;

2) the tuners realized by an hole in the full cell and a movable metallic cylinder have been substituted by two deformation tuners on the outer wall of the full cell;

3) the coupling window between the rectangular waveguide and the full cell have been strongly rounded to reduce the peak surface electric field and, therefore, the pulsed heating;

4) the cooling pipes have been improved and increased in number to guarantee a better gun temperature uniformity;

5) the structure have been realized without brazing but using special gaskets in order to maintain hard copper (instead of soft copper resulting from brazing process at high temperature) to reach higher accelerating field with lower break-down rate (BDR).