N. Bonifaci et al., WORK-FUNCTIONS FOR A HV CATHODE IN NONPOLAR LIQUIDS, IEEE transactions on dielectrics and electrical insulation, 1(4), 1994, pp. 657-662
When negative HV is applied to a needle of small radius of curvature (
r(p) < 0.2 mum) in nonpolar liquids, a detectable field emission curre
nt (I > x10(-12) A) is observed above a voltage U(FN), the Fowler-Nord
heim law. For larger point radii, only a regular current pulse regime
is detected above a threshold voltage U(S) (Trichel regime). Analysis
of these voltages U(s) and U(FN) as a function of conduction band ener
gy V0 of different liquids, shows that the apparent work function for
high electric field strengths in liquids is lower than the one without
applied field (2.1 compared to 4.5 eV for a tungsten cathode). This d
ifference can be explained if one assumes the existence of a plasma-li
ke layer around the HV cathode.