Work functions for a high-voltage cathode in non-polar liquids

When a negative high voltage is applied to a needle of small radius of curvature (r_p < 0.2 μm), a field emission current I(U_FN) is observed. For larger point radii, a regular current pulse regime is detected above a threshold voltage U_s. Analysis of the U_s(V_o) and U_FN (V_o) dependences shows that the apparent work function for high electric field strengths is lower than the one without voltage (1.5 eV compared to 4.5 eV). This difference can be explained if one assumes the existence of a plasma-like layer around the high-voltage cathode