Computer simulation of bunch lengthening effects caused by a third harmonic cavity in conjunction with deflecting cavities in 3 GeV Taiwan Photon Source

The effects of utilizing a third harmonic RF cavity in the lengthening mode have been investigated by computer simulation on quality of the electron beam as well as the emitted photons in the deflecting RF structures for TPS. For the obtained optimum synchronous and relative harmonic phases with a harmonic voltage of 0.472 MV the Touschek lifetime increases by around 8 hours. For the extreme operation mode of deflectors (h=8 and 6 MV deflecting voltage) the eventual horizontal and vertical emittances dramatically blows up to 3.07 nm-rad and 85 pm-rad, respectively. In addition, no significant difference in duration of the radiated pulses between operation of the main and the third harmonic RF cavities is observed. The results show that the intensity of the emitted X-ray pulses with a 0.5 ps FWHM reduces by 10% for the double RF operation in TPS.