100 keV vacuum sealed field emission gun for high resolution electron microscopy

A standalone 100 kV field emission gun (FEG) has been developed that can be installed and operated on a standard transmission electron microscopy optical column or custom designed high voltage columns. The FEG comprises thermally assisted cathode an asymmetric electrostatic lens operate from 20 to in ultrahigh vacuum (UHV) chamber. In its current configuration, the spherical chromatic aberration coefficients (Cs Cc, respectively) range of Cs = 607–670 mm Cc 60–87 at keV over working distances 50–206 exit plane unit. dedicated supply unit with ripples less than 1 ppm also developed. is transported under UHV does not require use SF6 gas during operation, as customary TEMs. Preliminary results operating Philips Tecnai 12 JEOL JEM-1400HR TEM show resolution gold (111) crystal planes 0.235 nm (200) 0.202 nm.