A microfabricated electrostatic field desorption ion source

The use of an electrostatic field desorption (EFD) ion source would constitute a significant advance in the design and operation of neutron generators. The results would directly benefit the use of neutron generators for active interrogation in the search for special nuclear material and the replacement of radioisotopic sources, particularly in man-portable scenarios. The novel EFD approach uses high electrostatic fields to produce pure atomic deuterium ions from a conductive surface, rather than ions produced from deuterium plasma. This concept has the potential to surpass current state of the art sealed neutron tube designs in many key performance areas including lifetime, reliability, efficiency, and neutron yield. Over the past few years a thorough study of the ion production and neutron yield of fabricated devices has been conducted. Devices that are 1 mm
²
consistently produce approximately 1000 n/cm2/s from the deuteron-deuteron reaction when operating in the dc mode. Electric fields of 20 V/nm are consistently achieved resulting in molecular deuterium ions from field ionization. Further increases in electric fields are necessary to reliably produce deuterons from field desorption. Both the modeling and experimental results to date are discussed.