Diagnosis and cure of a transverse instability in the NSLS VUV ring

In the National Synchrotron Light Source (NSLS) Vacuum Ultraviolet (VUV) ring, a beam instability occurred as a function of cavity tuner position, restricting the operating range of the tuner and requiring the cavity to operate at an elevated temperature to compensate. The cavity mode responsible for the instability was diagnosed and subsequently damped with a tuned probe terminated in 50 Omega . The instability was cured, and has not been observed up to the design current of 1-A stored beam.<
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