The pre-exponential voltage-exponent as a sensitive test parameter for field emission theories.

For field electron emission (FE), an empirical equation for measured current as a function of measured voltage has the form = exp[-/ ], where is a constant and and are constants or vary weakly with . Values for can be extracted (i) from simulations based on some specific FE theory, and in principle (ii) from current-voltage measurements of sufficiently high quality. This paper shows that a comparison of theoretically derived and experimentally derived values could provide a sensitive and useful tool for comparing FE theory and experiment, and for choosing between alternative theories. Existing methods of extracting -values from experimental or simulated current-voltage data are discussed, including a modernized 'least residual' method, and existing knowledge concerning -values is summarized. Exploratory simulations are reported. Where an analytical result for is independently known, this value is reliably extracted. More generally, extracted -values are sensitive to details of the emission theory used, but also depend on assumed emitter shape; these two influences will need to be disentangled by future research, and a range of emitter shapes will need examination. Other procedural conclusions are reported. Some scientific issues that this new tool may eventually be able to help investigate are indicated.