  This article proposes that we should think differently about predicting and
interpreting measured field electron emission (FE) current-voltage [I(V)]
characteristics. It is commonly assumed that I(V) data interpretation is a
problem in emission physics and related electrostatics. Many experimentalists
then apply Fowler-Nordheim plot methodology, developed in 1929. However, with
modern emitting materials this 90-year-old interpretation methodology often
fails (maybe in nearly 50% of cases), and yields spurious values for
characterization parameters, particularly field enhancement factors. This has
generated an unreliable literature, and validity checks on experimental I(V)
data are nearly always needed before use. A new check, supplementing existing
checks, is described. Twelve different "system complications" that, acting
singly or in combinations, can cause validity-check failure are identified. A
top-level path forwards from this unsatisfactory situation is proposed. The
term "field electron emission system (FE system)" is defined to include all
aspects of an experimental system that affect the measured I(V)
characteristics. The analysis of FE systems should now be regarded as a
specialized form of electronic/electrical engineering, provisionally called "FE
Systems Engineering". In this approach, the I(V) relationship is split: (a) the
current is expressed as a function I(F_C) of the local surface-field magnitude
F_C at some defined emitter surface location "C"; and (b) the relationship
between F_C and measured voltage V is expressed and determined separately.
Determining I(F_C) is mostly a problem in emission physics; determining the
relationship (F_C)(V) depends on system electrostatics and (for systems failing
a validity check) on other aspects of FE Systems Engineering. The scope of FE
Systems Engineering, and some related research implications and problems, are
outlined.
