  Low Work Function Tethers (LWT) is long conductors with a segment coated with
a material that has loosely-bounded electrons. Unlike a standard bare tether
equipped with an active electron emitter, LWTs close the electrical circuit
(cathodic contact) with the ambient plasma in a passive manner thanks to the
thermionic and photoelectric effects. This work presents experimental results
on a novel procedure for manufacturing LWT samples. Conductive substrates
(aluminum and copper) have been coated with graphene oxide doped with Cesium by
using a scalable, simple and cost-effective coating method with an airbrush.
Both GO and Cs-doped GO (GO/Cs) samples were characterized utilizing X-ray
spectroscopy, field emission scanning electron microscopy, four-point probe,
and ultraviolet photoelectron spectroscopy (UPS). They showed that GO sheets
were successfully doped with Cs atoms, which do not agglomerate on the graphene
sheets and do not form particles. The UPS results indicated that by doping GO
sheets with Cs, the work function of GO decreases from 4.6 eV to 3.09 eV, thus
increasing the applicability of GO as an electron emitter material.
