This one and-a-half cell gun typically runs with 12 MW of input power, which generates an 80 MV/m electric field on its Magnesium photocathode surface. A 1.3GHz standing-wave accelerating cavity increases the electron beam energy, from the 8 MeV produced by the RF gun, to 15 MeV.  The cavity operates in π/2 mode, with an average accelerating gradient of 7 MV/m.  It has large diameter irises to minimize the undesirable wakefields generated by the passage of high charge electron bunches. The charge of the electron bunches can be varied ranging from 1 pC to 100 nC.