Emittance measurement of space charge dominated electron beam confined by a longitudinal magnetic field

We propose a method for emittance measurement of a space charge dominated axisymmetric electron beam confined by a longitudinal magnetic field. In this method, the beam current is measured by a multi-layer Faraday cup to obtain the radial beam current profile through Able inversion. Based on the theory of the beam in a uniform focusing channel, the transverse electron temperature is uniquely defined by the shape of the current density profile. Measuring the current density profile allows a determination of the beam emittance. Because the method does not require using slits, the measurement has been remarkably simplified. The method has been adopted for a test beam. The emittance is found to be 20.2/spl pi/ mm/spl middot/mrad, which basically agrees with that from the slit-slit method.