To realize the shortest bunches possible, we check the bunch length as a function of two different bunching amplitudes. With the bucket fill set to 1.0 we observe the spectra compiled in attachment 1. The second attachment is recorded with a bucket fill 0f 0.2.

For an RF amplitude of 0.2 we do not observe bunches any more but a coasting beam. In the shottky spectrum we can resolve a shift of the signal and thereby adjust the electron cooler voltage to the bunching frequency to within 1 V.

U_e-cooler = -104410 V
I_e-cooler = 80 mA