Bunch lengthening control using the fourth harmonic cavity in the VUV ring

It is suggested that a harmonic cavity in a synchrotron storage ring can be used to change the shape of the bucket potential. Adjustment of the amplitude and phase of the harmonic component to flatten the slope of the waveform of the synchronous voltage will lengthen a stored bunch, thus extending the Touschek lifetime that is limiting the performance of the VUV ring. Beam-induced 211-MHz power in a fourth-harmonic cavity was used to check the feasibility of this concept. The data obtained during UV studies at the NSLS (National Synchrotron Light Source) are summarized.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>