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S-band Linac

Some experiments at the ATF require higher energies than what is available from the photoinjector. We use two traveling wave linac structures, known as 'SLAC sections' (from the famous 2-mile SLAC linac). Each section provides an acceleration given by:

Energy gain (in MeV) = 10.8*SQRT(Power in MW)-39.5*Current(in amps)

The current to be used is an equivalent steady state current. The microwave drive power, at a frequency of 2856 MHz, is provided by a single XK5 klystron tube (the old SLAC klystron). This tube can provide up to 25 MW. The ATF modulator can provide the XK5 klystron with high voltage for about 3 microseconds. This 3 microsecond pulse is called the macropulse. The repetition rate for the macropulses is from 1 to 6 per second. Within each of these macrobunches we accelerate from 1 to about 200 electron bunches (depending on the photoinjector's laser setting). These current bunches are called micropulses. The micropulse repetition rate is up to 81 MHz. 

Linac Schematic

Schematic layout of the ATF linac emphasizing the laser and rf loops, timing and frequencies.