2019-12-11
Production of C-Band structures continues

Comeb is currently manufacturing  C-Band linac structures for the ELI-NP project. Each structure is composed of 102 brazed copper cells with four waveguides that allow the excited HOMs to propagate and dissipate into silicon-carbide (SiC, EKASIC-P) RF loads. The cells have four tuners and eight cooling pipes to sustain a 100 Hz operation.

Dimensions of each cell have been optimized to simultaneously obtain:

a) the lowest peak surface electric field on the irises;

b) an average accelerating field of 33 MV/m with an available power from the klystron of 40 MW (conservative assumption);

c) the largest iris aperture compatible with the previous points in order to better pump the structure and reduce both the wakefields contribution and the filling time of the structure itself. This last point is also related to the needed input pulse length to fill the structure and, therefore, to the breakdown rate probability (at least from X Band) in the sense that a reduction of the pulse length strongly reduces the breakdown rate.

The structures' main parameters are listed below.

Structure type:  Quasi CG

Length:  1.8 m

Number of cells:  102 (including in/output couplers)

Working frequency:  5.712 GHz

Working mode:  2 pi/3 TW

Average acc. field:  33 MV/m

Repetition rate:  100 Hz

RF input power:  40 MW

RF pulse length:  0.8 μs

Filling time:  0.3 μs