The invention relates to an electron impact gas ion with high brightness and low energy spread. This high brightness is achieved by injecting electrons in a small ionization volume (from less than 1 μm to several tens of micrometers in size) from one side and extracting ions from the other. The electrons...http://www.google.de/patents/US7772564?utm_source=gb-gplus-sharePatent US7772564 - Particle-optical apparatus equipped with a gas ion source
