Capabilities of International Linear Collider and the Tesla Cavities

[pulsemaster]

I was just wondering about the International Linear Collider and the Tesla Cavities.
okay as i see it they run a 9 cell cavity with a field strength of 222kW RF at 1.3 ghz and a beam current of 8.5 ma.
my question is if they doubled the cavities to 18, what rf field strength would they need to obtain the same energy of electron on the output?
thanks

 

[pulsemaster]

okay you did not laugh at the mistake in my question.

so question is :
if they double the cells in each cavity section from 9 to 18. what rf field strength would they need to obtain the same energy of electron on the output? (power remains constant)
thanks