As part of the ongoing developments being undertaken by the International Design Team, to achieve an appropriate stage of technology production readiness for the International Linear Collider, a coordinated activity tasked to develop suitable solutions for the critical crab cavity technology has been initiated since November 2020, a record for which can be found here: https://agenda.linearcollider.org/category/256/
The progress for these developments has been driven by the requirement to match ILC performance expectations and principally to achieve the associated operational and implementation specifications for both a 250 GeV and 1 TeV centre of mass capability. There are currently 5 different technology solutions being designed from groups in Europe and USA, who are each progressing to be able to perform a suitable down-selection process (for 2 cavity options), in order to then facilitate a next stage prototyping validation.
