SC RF Accelerating Structures

Fig.: Photograph of a Cornell Booster cavity (top), draw of the bERLinPro Booster cavity with details of its optimized coupler tip (bottom) 

The concept pursued by HZB at the moment is to combine Cornell’s ERL main Linac cell design with a waveguide based HOM damping design mainly developed by JLab.

To allow for variable coupling and operation at high loaded quality factor (low coupling strength, QL=5e7), one waveguide is replaced by a TTF-III style fundamental power coupler.

At the moment end cell studies are performed to achieve a field flat design with highest damping of the HOMs. Following studies of the whole coupled structure of a three cavity string need to demonstrate, that propagating HOM are sufficiently damped to avoid further unwanted beam-cavity interaction.  

Fig.: Draft of the present linac cavity layout (top), field distribution of a localized quadrupole mode at 2.4 GHz (bottom): one of the cavity optimization goals is to minimize the amplitudes of dominant HOMs.

Fig.: Draft of the bERLinPro booster module

Linac Module

Detailing of the linac module starts as soon as the linac cavity design is fixed.