Abstract
A low-emittance electron gun has been developed for the x-ray free electron laser facility at SPring-8 that was named as SACLA. The gun uses a single-crystal cerium hexaboride (CeB6) cathode as a thermionic emitter to produce a low-emittance electron beam. A pulsed high-voltage of 500 kV is applied on the cathode to obtain more than 1 A peak current without emittance degradation. A normalized emittance of the beam was measured to be 0.6 mm mrad. This value is satisfied with a requirement of SACLA. The CeB6 electron gun is briefly reviewed in this paper.
