Helium Detection via Field Ionization from Carbon Nanotubes

Abstract

A novel, high-efficiency detector for neutral atoms such as helium is described. The design uses multiwalled carbon nanotubes (MWNTs), grown by chemical vapor deposition on a steel support wire. Application of a positive bias to the MWNTs generates electric fields sufficient to field-ionize passing gas-phase atoms. Under ultrahigh vacuum conditions, the detector was demonstrated to be capable of ionising and detecting even helium gas, the element with the highest ionization potential.

A novel highly sensitive gas ionization sensor for ammonia detection

“…CNTs were usually utilized as electrode materials due to its large field enhancement factor that can efficiently converge the electric field energy and initiate corona discharges at low voltages. However, CNTs could be oxidized and degraded easily under an oxygen contained atmosphere and high electric current as a light element nanostructure [5,6]. So some other kind of 1D nanomaterials such as ZnO, Au nanowires arrays also were used for gas ionization sensor to enhance the stability of the sensor [7][8][9].…”

MEMS gas ionization sensor with palladium nanostructures for use at ambient pressure

“…Additionally the surface of one or both electrodes can be modified to locally enhance the field strength, e.g. by 1D-nanostructures such as carbon nanotubes (CNTs) [1][2][3][4][5][6], ZnO or Au nanowires [7][8][9]. These nanostructures can significantly improve the sensor performance, but there are also a few drawbacks.…”

Current-voltage relation for a field ionizing He beam detector

“…18 While having some relevance to detector applications, it is intensity and brightness rather than overall ion current that is the desired for FIB application. Multiple detectors used as either two dimensional arrays 19,20 or "activated" wires in which sharp filaments are grown or deposited on a surface 21,22 have been used to produce high ion current for sample analysis but at the time of this writing activated surfaces have shown very little promise as high efficiency, high resolution field ion detectors, and two dimensional arrays would require considerable development.…”