L ext.

1. Original CLIC Module Easy way #1. L total=2xLactive+ 2xL ext. +Ld + Lm Ld Lm L active L ext. L total=2xLactive+ 2x55.6+ 11 + 8 L total (34 cells/PETS)= 556 mm Quad/BPM/flanges available = 407 mm CLIC Module in TBTS 1 PETS x Quad., direct scaling from existing one with increased (to be kept in layout) length: L total= L’ active+ L ext. + Lm Lm L’ active = 500.2 (80 cells)

2. Easy way #1. continued With longer active length (80 cells) and drive beam current 30 A and bunch length of 1 mm, the power produced with a single PETS is 63 MW! Practically enough (cf. 65 MW) to feed one single structure! However the 25 A is more reasonable value (Roberto’s) so if we can increase the length by 10 cm – up to 600 mm (97 cells)? This will be straightforward scenario, I think we can feet this new length, if the PETS BPM are not there, or rather short (or shorter quadrupole, or even single quadrupole). So the module 1 PETS x 1 AS structure (6 empty structures): Quad 34 cm 25 A 600 mm + Lext +Lm =664 mm 65 MW 65 MW Another way to keep the 500 mm/PETS, is to modify PETS design – PETS with reduced aperture: from 23 mm diameter to 20.8 mm diameter. This will require quite a design work: new matching cells (extractor can be kept as it is). BUT still possible (CIEMAT can do design modifications – good chance)!!! Note: PETS produces 0.5 power and only 2 structures accelerates

3. Not very Easy way. As a boundary we still can keep the module layout similar to CLIC, So that 4 PETS/module of original length 34 cell (213 mm). To feed now 4 structures: 1 PETS/structure, the PETS aperture must be reduced from 23 mm diameter down to 13.6 mm (beta=18%!) in order to recover factor 4 in current with 0.5 the power to be produced! 25 A 13.6 mm PETS 65 MW 65 MW 65 MW 65 MW Note: Completely new PETS design (not sure even if now octants could work), As well, compare it to the 50 MW klystron with aperture ~ 15.5 mm diameter.