Performance of an electron gun for a high‐brightness X‐ray generator

A prototype thermionic electron gun for a high‐brightness X‐ray generator has been developed. Its extraction voltage and design current are 60 kV and 100 mA (DC), respectively. The X‐ray generator aims towards a maximum brilliance of 60 kW mm −2 . The beam sizes at the rotating anticathode must therefore be within 1.0 mm × 0.1 mm and a small beam emittance is required. The fabricated electron gun optimizes an aperture grid and a Whenelt electrode. The performance of the prototype electron gun measured using pulsed‐beam tests is as follows: maximum beam current, 85.7 mA; beam focus size at the rotating anticathode, 0.79 mm × 0.13 mm. In DC beam tests, FWHM beam sizes were measured to be 0.65 mm × 0.08 mm at the rotating anticathode with a beam current of 45 mA. The beam current recently reached ∼60 mA with some thermal problems.