Three methods for high density and high current electron beam brightness measurement

This paper presents the principle and methods for measuring brightness of high-density and high-current electron beam. Measurement were performed on a 4 MeV LIA injector with a time-resolved measurement system using three methods: the emittance measurement method, beam collimator without magnetic field method, and beam collimator with magnetic field method. This paper describes the concept of the high current beam brightness and typical theoretic analysis of beam measurement. A time-resolved framing photography has been set up for triple-pulsed beam emittance measuring, which can capture beam divergence image and obtain electron beam root mean square emittance. A series of beam emittance data has been obtained in the 4 MeV LIA injector, the normalized beam emittance is about 114 mmmrad and the double pulse normalized emittance is 456 mmmrad. According to the electron beams Gaussian distribution, a primary analysis is carried out, which gives the numerical relations between beam root mean square emittance, measured emittance and edge emittance.