Using transient waveform recorders to measure and store beam parameters

Transient waveform digitizers are used to measure the tunes in the Stanford Linear Collider (SLC) damping rings. Since the beam injection and extraction from these rings occurs at a high rate (120 Hz) and because of the stringent extracted beam stability requirements, simpler asynchronous resonant excitation spectrum analyzer measurements are not possible. The beam position monitor signals are processed, digitized, and a Fast Fourier Transform (FFT) is applied to find the tunes. The coherent beam motion at injection, even though it damps quickly, is large enough to provide a strong tune signal. Recently, this technique has also been applied to several longitudinal signals. The results from these monitors are recorded at six-minute intervals in the SLC control system history buffers. This paper will describe the hardware setup and the software used to process the data, and will present some of the results