Micro Mass Spectrometer Using Triode Electron Emitters with a Planar Carbon-Nanoparticle Cathode as Ion Source

Using micromachining techniques, a miniature time-of-flight mass spectrometer (TOF-MS) was fabricated which consisted of ion-source and ion-separator plates. The dimension of the assembled device was 11 mm times 11 mm times1.1 mm. The key part of the ion source was a triode electron emitter with a planar carbon-nanoparticle (CNP) cathode. CNP was one of the best cathode materials to build triode electron emitters because of the smooth surface morphology of CNP films in addition to their excellent emission characteristics which allowed low turn-on gate voltage and stable operation. The operation of each plate was confirmed successfully through separate tests. In particular, ion generation was verified via electron bombardment for ambient air and acetone molecules.