Design and operation of a bunched-beam, phase-spread measurement

A bunch-length monitor system has measured the relative changes in the temporal beam-bunch length of an H{sup {minus}}, 2.5 MeV beam. This system includes a non interceptive electromagnetic probe, associated RF processing electronics, and an software algorithm. The probe is an axial symmetric capacitive pickup whose output signal is proportional to the bunched beam image currents traveling through its bore. The RF electronics processes the beam-induced signal into a ratio of its fundamental and fifth-harmonic Fourier components and provides a time-varying output voltage proportional to the phase length of the beam-bunch. This paper reviews the measurement hardware, software algorithm, and operational experience.