ETA-II beam brightness measurement

ETA-II resumed operation in the Fall of 1990 with the injector and first two ten-cell accelerating blocks and nominal electron beam parameters of 1500 A, 2.5 MeV, and 70-ns pulse width at 1 Hz PRF. The beam brightness diagnostics consisted of a Cerenkov foil view port and a pepper-pot emittance diagnostic. The Cerenkov foil experiment was used to determine the beam energy at the accelerator exit. The pepper-pot emittance diagnostic was used to determine the whole beam brightness. The brightness as a function of beam radius and time within the beam pulse was also measured. The brightness is defined as the ratio of the beam current within a given radius to the normalized four-dimensional volume occupied by particles within that radius.<>