Abstract: Provided is a Schottky emitter having the conical end with a radius of curvature of 2.0 ?m on the emission side of an electron beam. Since a radius of curvature is 1 ?m or more, a focal length of an electron gun can be longer than in a conventional practice wherein a radius of curvature is in the range of from 0.5 ?m to not more than 0.6 ?m. The focal length was found to be roughly proportional to the radius of the curvature. Since the angular current intensity (the beam current per unit solid angle) is proportional to square of the electron gun focal length, the former can be improved by an order of magnitude within a practicable increase in the emitter radius. A higher angular current intensity means a larger beam current available from the electron gun and the invention enables the Schottky emitters to be used in applications which require relatively high beam current of microampere regime such as microfocus X-ray tube, electron probe micro-analyzer, and electron beam lithography system.

Abstract: Provided is a Schottky emitter having the conical end with a radius of curvature of 2.0 ?m on the emission side of an electron beam. Since a radius of curvature is 1 ?m or more, a focal length of an electron gun can be longer than in a conventional practice wherein a radius of curvature is in the range of from 0.5 ?m to not more than 0.6 ?m. The focal length was found to be roughly proportional to the radius of the curvature. Since the angular current intensity (the beam current per unit solid angle) is proportional to square of the electron gun focal length, the former can be improved by an order of magnitude within a practicable increase in the emitter radius. A higher angular current intensity means a larger beam current available from the electron gun and the invention enables the Schottky emitters to be used in applications which require relatively high beam current of microampere regime such as microfocus X-ray tube, electron probe micro-analyzer, and electron beam lithography system.

Abstract: This invention relates to heating apparatus and methods with particular applications for growing a nanofibre, and to nanotips fabricated by such methods and apparatus. Embodiments of the invention can be implemented to provide nanotips for electron gun sources and scanning probe microscopy. A nanotip fabrication apparatus includes a heater for heating an object in the presence of an electric field. The heater comprises: a substantially planar electrically conductive heating element configured to define at least one aperture; a support to mount the heated object such that it protrudes through said aperture; and at least one electrical connection to said heating element. In use, the heating element can be biased by said at least one electrical connection such that the electric field in the vicinity of the object is substantially perpendicular to the plane of the element.