Editing Compact Linear Collider (section)

=== Main beam ===
The electrons needed for the main beam are produced by illuminating a [[gallium arsenide|GaAs]]-type [[cathode]] with a Q-switched polarised [[laser]], and are longitudinally polarised at the level of 80%.<ref name="2018_proj_imp">
{{cite journal |last1=Aicheler |first1=M. |last2=Burrows |first2=P.N. |last3=Catalan |first3=N. |last4=Corsini |first4=R. |last5=Draper |first5=M. |last6=Osborne |first6=J. |last7=Schulte |first7=D. |last8=Stapnes |first8=S. |last9=Stuart |first9=M.J. |title=The Compact Linear Collider (CLIC) – Project Implementation Plan |date=20 December 2018 |journal=CERN Yellow Reports: Monographs |volume=4 |doi=10.23731/CYRM-2018-004|arxiv=1903.08655 |doi-access=free
}}</ref> The [[positron]]''s'' for the main beam are produced by sending a 5&nbsp;GeV electron beam on a [[tungsten]] target. After an initial acceleration up to 2.86&nbsp;GeV, both electrons and positrons enter damping rings for [[Beam emittance|emittance]] reduction by [[radiation damping]]. Both beams are then further accelerated to 9&nbsp;GeV in a common booster linac. Long transfer lines transport the two beams to the beginning of the main [[CERN Hadron LINACs|linacs]] where they are accelerated up to 1.5&nbsp;TeV before going into the Beam Delivery System (BDS), which squeezes and brings the beams into collision. The two beams collide at the IP with 20&nbsp;m[[radian|rad]] crossing [[angle]] in the horizontal plane.<ref name=2018_proj_imp/>