Editing Compact Linear Collider (section)

=== Drive beam ===
Each Drive Beam complex is composed of a 2.5&nbsp;km-long linac, followed by a Drive Beam Recombination Complex: a system of delay lines and combiner rings where the incoming beam pulses are interleaved to ultimately form a 12&nbsp;GHz sequence and a local beam [[electric current|current]] as high as 100[[ampere|A]].<ref name=2018_proj_imp/> Each 2.5&nbsp;km-long Drive Beam linac is powered by 1&nbsp;GHz [[klystron]]''s''. This produces a 148&nbsp;μs-long beam (for the 1.5&nbsp;TeV energy stage scenario) with a bunching [[frequency]] of 0.5&nbsp;GHz. Every 244&nbsp;ns the bunching phase is switched by 180 degrees, i.e. odd and even buckets at 1&nbsp;GHz are filled alternately. This phase-coding allows the first factor two recombination: the odd bunches are delayed in a Delay Loop (DL), while the even bunches bypass it. The [[time of flight]] of the DL is about 244&nbsp;ns and tuned at the picosecond level such that the two trains of bunches can merge, forming several 244&nbsp;ns-long trains with bunching frequency at 1&nbsp;GHz, separated by 244&nbsp;ns of empty space. This new time-structure allows for further factor 3 and factor 4 recombination in the following combiner rings with a similar mechanism as in the DL. The final [[time]] structure of the beam is made of several (up to 25) 244&nbsp;ns-long trains of bunches at 12&nbsp;GHz, spaced by gaps of about 5.5&nbsp;μs. The recombination is timed such that each combined train arrives in its own decelerator sector, synchronized with the arrival of the Main Beam. The use of low-frequency (1&nbsp;GHz), long-pulse-length (148&nbsp;μs) klystrons for accelerating the Drive Beam and the beam recombination makes it more convenient than using klystrons to directly accelerate the Main Beam.<ref name=2018_proj_imp />[[File:CLIC two beam module installed in the CLIC Test Facility at CERN (CTF3).jpg|thumb|Image of the CLIC Two Beam Module in the CLIC Test Facility, CERN ([[CTF3]]). The beam travels from left to right.|alt=|280x280px]]