Patent ID: 8242674

Claim:
Apparatus for producing a beam of charged particles by field emission, comprising: a field emitter arranged in or pointing into a vacuum space and comprising at least one field emitter tip for an emission of particles, a magnetic field generator attributed to the particle emitter for bunching or focusing of the particle beam emitted, wherein the particle emitter with its emitter tip is built by electrically conductive structures positioned on the substrate surface turned away from the magnetic field generator, the substrate being electrically insulating at least at this surface, and the substrate serving as separating wall between said vacuum space and the atmospheric space situated outside the vacuum space, and the magnetic field generator being arranged outside the vacuum space at the side of the substrate turned away from the emitter structures side; wherein at least a part of conductive layers of said electrically conductive structures arranged on or in the surface of the substrate turned to the side of said magnetic field generator extending through an area including the vacuum space and the insulating substrates and to an area turned to atmosphere, wherein said conductive layers of said electrically conductive structures represent electrical conductive pads, wherein said magnetic field generator consists of a permanent magnet having small dimensions of at maximum some few mm, and the magnetic field generated by said magnetic field generator extends at maximum some few mm into said vacuum space.